Power-to-Chemicals (P2C) via plasma catalysis of CH4 and...

Power-to-Chemicals (P2C) via plasma catalysis of CH4 and CO2

Zunrong Sheng, Yoshiki Watanabe, Chen Xiaozhong, Tomohiro Nozaki* Dept of Mechanical Engineering, Tokyo Institute of Technology

*Corresponding: [email protected]

Syngas is a gaseous fuel consisting mainly of CO and H2. Syngas production is an important process for various synthetic chemicals, for example, Fischer-Tropsch synthesis, methanol synthesis and ammonia synthesis. Currently, syngas is produced in great quantities from methane via catalytic processes based on dry methane reforming (DMR), steam methane reforming (SMR) and partial oxidation of methane (POM) [1]. Among these technologies, DMR (CH4 + CO2 → 2CO + 2H2) has gained much attentions as the utilization of greenhouse gases (CH4 and CO2) and a good approach to utilize biogas consisting primarily these gases in recent years. However, DMR is strongly endothermic and requires substantial temperature (T > 800 K). Therefore, it is inevitable that the heat of reaction is supplied by combustion of an initial CH4 feed. The combustion causes exergy loss and formation of CO2 and NOx. Moreover, DMR has another problem which solid carbon is deposited on catalyst as by-product and causes serious catalyst deactivation.

Combination of nonthermal plasma and heterogeneous catalysts is considered as one of the viable solutions to these problems. Plasma-generated reactive species promote reforming reaction at relatively low temperature in a non-equilibrium approach [2-5]. The application of nonthermal plasma poses two important features; high reactivity of nonthermal plasma and high selectivity of catalyst at much lower temperature than conventional thermal catalysis. Moreover, nonthermal plasma suppresses the formation of solid carbon as a result of the enhanced gasification of coke by CO2. In our previous work, we confirmed experimentally that CH4 and CO2 conversion were improved by the combination of dielectric barrier discharge (DBD) and La:Ni/Al2O3 catalyst [6]. However, since interaction between DBD and heterogeneous catalysts are quite complicated, reaction mechanisms have yet to be fully understood. In order to further increase the efficiency, it is essential to elucidate plasma-induced reaction enhancement mechanisms.

We performed kinetic study of DBD and catalyst hybrid reaction to identify the apparent activation energy so that the plasma-induced synergy is compared quantitatively. Figure 1 shows Arrhenius plot of DMR for thermal catalysis, as well as plasma catalysis at different frequency (12 kHz and 100 kHz). The overall activation energy for thermal catalysis in the reaction-limited regime was measured as 91 kJ/mol, which is in good agreement with the published data [7]. The activation energy decreased from 90 to 83 kJ/mol by low frequency DBD catalysis (12 kHz). In the adsorption-limited regime, activation energy decreased from 53 to 47 kJ/mol (12 kHz) and to 28 kJ/mol (100 kHz). The result implies the rate-limiting step, i.e. CH4 dissociative chemisorption, was promoted by DBD. There is a much greater influence of DBD when it is operated at high frequency because of larger discharge current is generated. Meantime, the analysis of discharge behavior indicates the increase in electric field, or the mean electron energy, has a minor effect of the synergistic effect.

[1] A.A. Ibrahim et al, J. Chem. Eng. Jpn., 52, 232 (2019) [2] K. Sakata et al, J. Inst. Electrostat. Jpn., 43, 2 (2019) in

Japanese [3] S. Kameshima et al, Catal. Today, 256, 67 (2015) [4] S. Kameshima et al, J. Phys. D, 51, 114006 (2018) [5] Z. Sheng et al, J. Phys. D: Appl. Phys., 51, 445205

(2018) [6] Z. Sheng et al, Plasma Chemistry and Gas Conversion,

IntechOpen, DOI: 10.5772/intechopen.80523. [7] U. Olsbye et al, Ind. Eng. Chem. Res., 36, 5180 (1997)

Fig. 1 Arrhenius plot for CH4 activation

2D/1D wearable textile-based energy harvesting and storage devices

Jin Pyo Hong

Research Institute of Natural Science, Novel Functional Materials and Device Laboratory, Department of Physics, Hanyang University, Seoul, 04763, Republic of Korea

Wearable energy harvesting devices as the basic building blocks for independent power sources are highly promising for use in flexible and portable smart electronic applications. In this regard, the use of conductive textile substrate in triboelectric nanogenerator (T-TENG) converting sustainable mechanical energy to electricity has emerged as an alternative option for efficient power generation regardless of the surrounding environment. Here, we address the enhanced electrical performance of T-TENG devices employing 2D surface engineered and engineered polydimethylsiloxane (SE-PDMS) layers coated on the conductive Ni-Cu textiles. Control and manipulation of PDMS surfaces represent one of key approaches in this work, where in-situ 2-step reactive ion plasma (RIE) treatments and dip coating process were particularly conducted. In addition, one-dimensional (1D) conductive flexible and stretchable yarn (1D CBY) as a generic step for the development of 1D CBY-based energy harvesters through a weaving technology was tested, along with the manipulation of hierarchically nanostructured surfaces on the 1D CBYs for enhancing power generation through a large contact surface area. The 1D CBY-TENGs with diverse stack configurations are also tested as a simple integration scheme. Finally, the performance of 1D yarn-based supercapacitor is discussed. Our approach may establish a useful and simple route for developing a self-powered wearable smart electronics.

Methane production for energy storage using low temperature plasma

Masaharu SHIRATANI, Masashi IDEGUCHI, Akihisa YAMAMOTO,

Daisuke YAMASHITA, Kunihiro KAMATAKI, Naho ITAGAKI, Kazunori KOGA

Kyushu University, Japan

[email protected]

The power to gas processes have the potential to solve long-term and large-scale energy storage

problems as well as reduce CO2 emissions [1]. Among many processes CO2 methanation is one of the vital processes for the production of synthetic natural gas. Moreover, biogas contains up to 50% CO2 and by transforming CO2 into methane, the production in existing plants can be doubled. Methane is the cleanest fossil fuel for electricity production helping meet growing energy needs. Methane is easy to handle and can be stored as LNG. For methane production, CO2 is recycled as the Sabatier reaction;

CO2+4H22→CH4+2H2O, ΔH = −165.0 kJ/mol. (1) Here, we converted CO2 to CH4 under low pressure and low temperature using a plasma-catalyst combination method [2, 3].

We measured time evolution of CO2 conversion and CH4 yield. Plasma was ignited at t = 0 s. CO2 conversion rapidly increases during 100 s after plasma ignition. Then, it slightly increases and becomes nearly constant around 65%. CH4 yield is little before 20 s and it continues to increase until 480 s. CO2 conversion has a fast rise time of 54 s, whereas CH4 yield has a slower rise time of 657 s due to slow temperature rise of catalyst. The results indicate the methanation mechanism; CO2 is decomposed by electron impact, and CH4 is generated on the catalyst surface. In other words, CH4 generation rate is mainly determined by the surface reaction rate. The catalyst is heated by ion bombardment without extra heating, and source gases are excited and dissociated by electron impact. CH4 yield is 5% at the Cu catalyst temperature of 430 K. The activation energy of CH4 generation rate is 27.5 kJ/mol, which is 1/3 of that of the Sabatier reaction using conventional catalysts. The plasma-catalyst combination method significantly reduces the activation energy, and is an effective methanation method, especially under low temperature and low pressure conditions. Further discussion as well as recent progress will be reported at the symposium. References: 1) C. Mebrahtu, et al, Studies in Surface Science and Catalysis 178, 85-103 (2019). 2) S. Toko, R. Katayama, K. Koga, E. Leal-Quiros, M. Shiratani, Sci. Adv. Mater. 10, 655-659 (2018). 3) S. Toko, S. Tanida, K. Koga, M. Shiratani, Sci. Adv. Mater. 10, 1087-1090 (2018).

New visible light driven blue TiO2 photocatalysts and their energy conversion

Hyoyoung Lee1,2,3,4 * 1Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan

University, Suwon 16419, Korea

2Department of Chemistry, 3Department of Energy Science and 4Department of SAINT, Sungkyunkwan University (SKKU), Suwon, 16419, Republic of Korea

Email: [email protected]

Over more than 50 years, the phase-mixed anatase and rutile crystalline P25 TiO2 has been one of the most widely applied metal oxides as photo catalyst under UV light. Until now, however, there is almost no report about the visible light driven P25 TiO2 photoctalysts without a help of co-catalysts. To enhance a visible light absorption as well as an efficient charge separation, a conceptually new approach should be considered.

Here, we demonstrate the crystalline phase-selectively disorder engineered P-25 TiO2 nanoparticles using simple room-temperature solution processing, which maintains the unique three-phase interfaces (called Hyoyoung Lee’s blue TiO2) composed of ordered white-anatase and disordered black-rutile [1] or ordered white-rutile and disordered black-anatase [2] with open structures for easy electrolyte access. The order/disorder/water junction efficiently separates the redox sites for oxidation and reduction processes, leading an excellent photocatalytic activity under solar and visible light.

In addition, the heterostructured hybrid metal oxide photocatalysts have been used for various applications such as CO2 reduction reaction (CO2RR). We selected WO3 and blue TiO2 as the components of a Z-scheme metal oxide hybrid photocatalyst system. The resulting blue TiO2/WO3 hybrid has a Z-scheme charge transfer system that provides good electron-hole separation by forming contact interfaces and is stable under an oxygen atmosphere. To achieve both of high selectivity and yield for producing CO only in the solar light-driven photocatalytic CO2RR, we loaded Ag NPs, which provided 100% selective CO [3].

[1] Kan Zhang, Luyang Wang, Jung Kyu Kim, Ming Ma, Ganapathy Veerappan, Chang-Lyoul Lee, Ki-jeong Kong, Hyoyoung Lee*, Jong Hyeok Park*, Energy & Environmental Science, 9, 499-503 (2016). [2] Hee Min Hwang, Simgeon Oh, Jae-Hyun Shim, Young-Min Kim, Ansoon Kim, Doyoung Kim, Joosung Kim, Sora Bak, Yunhee Cho, Viet Q.Bui, Thi Anh Le, Hyoyoung Lee*, ACS Applied Materials & Interfaces, 11, 39, 35693-35701 (2019). [3] C. T. K. Nguyen, N. Q. Tran, S. Seo, S. Oh, J. Yu, M. Kim, T. A. Le, J. Lee, Hyoyoung Lee*, Materials Today, In print (2019).

Corresponding author: Yuichi Imai E-mail address: [email protected]

Development of DLC Deposition Method for a Lumen of Small-diameter Long-sized Tube and the Evaluation of Biocompatibility in vivo

Yuichi Imai1,2, Shinsuke Kunitsugu3, Yasuhiro Fujii4, Takashi Goyama4, Daiki Ousaka4 , Susumu Oozawa4, Tatsuyuki Nakatani1

1Institute of Frontier Science and Technology, Okayama University of Science 1-1 Ridai-cho, Kita-ku, Okayama 700-0005, Japan

2STRAWB Inc. 1542-1 Nakahara-cho, Takahashi-shi, Okayama 710-0045, Japan

2Industrial Technology Center of Okayama Prefecture 5301 Haga Okayama-shi, Okayama 701-1296, Japan

4Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University 2-5-1, Shikata-cho, Kita-ku, Okayama, 700-8558, Japan

ABSTRACT

Small-diameter long sized medical tube such as Expanded-polytetrafluoroethylene (ePTFE) the small diameter less than 6 mm vascular grafts exhibit a low patency rate because of thrombosis or thick neointimal formation. In this study, AC high-voltage methane plasma Chemical Vapor Deposition is employed to form the bio-compatibilized inner wall of a small-diameter long-sized medical tube is developed to improve the patency rate.

1. Introduction

A Diamond-Like Carbon (DLC) film that was deposited by a plasma process using an electric discharge. Generally, DLC films have been attracting increasing attention to be used in bio-compatibilized films that can be used in case of medical equipment such as coronary artery stents [1]. There is an increase in the requirement of various kinds of artificial vascular grafts because of the increasing number of patients with arterial vascular diseases. Hence, in this study, a novel AC high-voltage methane plasma Chemical Vapor Deposition (CVD) method is proposed. 2. Method

Figure 1 shows the schematic of the system configuration of the DLC deposition equipment by utilizing the developed AC high-voltage methane plasma CVD method. Methane gas was used as the source gas, which depicted a flow rate of 96 sccm by a mass flow controller. At an operational pressure 39 Pa along with a constant AC voltage of 5 kV and a frequency of 10 kHz as the deposition conditions, the electrode was placed on only one side of a small-diameter long tube, and voltage was applied with the chamber serving as the earth electrode. The function generator was set to an offset negative voltage of 2 kV. A preliminary animal study was performed on beagles to evaluate the effects of the newly

developed DLC-coated ePTFE vascular graft.

3. Results and Discussion Methane plasma was uniformly formed inside the small-

diameter long tube from the side of the electrode toward the end of the tube. The biocompatibility of the ePTFE vascular grafts using the DLC (a-C:H) film, which was coated by AC high-voltage methane plasma CVD, was assessed by animal experiments described above. Figure 4 presents the results of the pathological evaluation. A considerably thinner and more uniform vascular intima was spread out on the DLC-coated inner ePTFE surface.

4. Concluding Remarks

In this study, an AC high-voltage methane plasma CVD method was proposed. Results confirmed the confinement of methane plasma in the small-diameter long tube of the ePTFE vascular grafts (diameter of 4 mm and overall length of 150 mm) and the formation of a thin a-C:H film on the inner wall by Raman analysis. Additionally, it can be inferred that the a-C:H film may contribute to the formation of uniform and thin neo-intima in the ePTFE vascular grafts.

References [1] T. Nakatani, K. Okamoto, I. Omura, S. Yamashita,

J. Photopolym. Sci. Technol., 20, (2007) 221.

Fig.1 Schematic of the experimental apparatus. Fig.4 Histologic sections that were obtained from the

carotid artery.

Triboelectrification for Powering Wearable and Implantable Electronics

Sang-Woo Kim

School of Advanced Materials Science and Engineering, Sungkyunkwan University (SKKU), Suwon 16419,

Republic of Korea

E-mail: [email protected]

Energy harvesting systems based on triboelectric nanomaterials are in great demand, as they can provide routes for the development of self-powered devices which are highly flexible, stretchable, mechanically durable, and can be used in a wide range of applications. Our recent research interest mainly focuses on the fabrication of high-performance triboelectric nanogenerators (TENGs) based on various kinds of nanomaterials. Flexible TENGs exhibit good performances and are easy to integrate which make it the perfect candidate for many applications, and therefore crucial to develop. In this presentation, I firstly introduce the fundamentals and possible device applications of TENGs, including their basic operation modes. Then the different improvement parameters will be discussed. As main topics, I will present a couple of recent achievements regarding highly stretchable transparent flexible TENGs, textile-based wearable TENGs, highly robust and efficient TENGs with multifunctional materials, etc. The recent research and design efforts for enhancing power generation performance of TENGs to realize self powering of wearable and body-implanted electronics will also be discussed in this talk. Finally I am going to introduce a 2D materials-based tribotronics for possible future application toward tactile sensors, robots, security, human-machine interfaces, etc. <References> - “Transcutaneous ultrasound energy harvesting using capacitive triboelectric technology”, R. Hinchet, H.-J. Yoon, H. Ryu, M.-K. Kim, E.-K. Choi, D.-S. Kim and S.-W. Kim, Science, 365, 491-494 (2019) - “Butylated melamine formaldehyde as a durable and highly positive friction layer for stable, high output triboelectric nanogenerators”, S.S. Kwak, S. Kim, H. Ryu, J. Kim, U. Khan, H.-J. Yoon, Y.H. Jeong and S.-W. Kim, Energy & Environmental Science, 12, 3156-3163 (2019) - “Sustainable direct current powering a triboelectric nanogenerator via a novel asymmetrical design”, H. Ryu, J. H. Lee, U. Khan, S. S. Kwak, R. Hinchet and S.-W. Kim, Energy & Environmental Science, 11, 2057-2063 (2019)

Physical Applications of DNA thin films

Sung Ha Park

Department of Physics and Sungkyunkwan Advanced Institute of Nanotechnology (SAINT), Sungkyunkwan University, Suwon 16419, Korea

[email protected] Nanobiotechnology has evolved into a unique interdisciplinary field involving physics, materials science, chemistry, biology, computer science, and multiple engineering fields [1]. Likewise, DNA nanotechnology is a quickly developing field with essentially no overwhelming technical difficulties inhibiting progress toward designing and fabricating new shapes of DNA nanostructures in all dimensions. In this field, researchers create artificial DNA sequences to self-assemble into target molecular nanostructures. The well understood Watson–Crick base-pairing rules are used to encode assembly instructions directly into the DNA molecules which provide basic building blocks for constructing functionalized nanostructures with two major features: self-assembly and self-alignment. In this talk, we present on self-assembled various DNA nanostructures with specific patterns generated by implementation of certain logics [2]. In addition, we address DNA applications in NT/IT/ET (such as algorithm, computer, and energy generator made of DNA), which will show feasibility to construct various useful and efficient devices and sensors [3-5]. [1] S. Vellampatti et al, Biosensors and Bioelectronics, 126, 44 (2018)

[2] H. Cho et al, ACS Nano, 12, 4369 (2018)

[3] S. Vellampatti et al, ACS Appl. Mat. & Int., 10, 44290 (2016)

[4] M. R. Kesama et al, ACS Appl. Mat. & Int., 8, 14109 (2016)

[5] J. Kim et al, Nat. Nanotech., 10, 528 (2015)

Novel design of 2-dimensional metal nanostructure electrodes for next-generation

supercapacitors

Geon-Hyoung An*

Department of Energy Engineering, Gyeongnam National University of Science and

Technology


The exhaustion of fossil fuels and environmental contamination has urgently prompted the

development for renewable and clean energy sources such as geothermal energy, solar energy, and

wind power. However, the inconstant nature sources signify that these cannot be eventually

applied in electrical power grids and applications, which require the balancing technologies using

the energy storage devices such as Li-ion batteries and supercapacitors. In this context, owing to

their high-power density, fast charging and discharging ability, long cycle time, and safe operation,

supercapacitors can use as effective energy storage devices to supply rapid energy while using

renewable energy sources. Generally, supercapacitors composed of three main components: the

electrode, electrolyte, and separator. Among them, the research and development of electrode

materials will be key technologies to improve the energy storage performance. Thus, we

successfully synthesized 2-dimensional metal nanostructure materials for use in electrode

materials, which can provide the increased electrochemical active sites and the enhanced ionic

diffusion performance, leading to the enhanced electrochemical performance. These results will be

discussed in symposium in detail.

Preparation of Quantum-Confined Perovskite Materials and Its Applications

Chang-Lyoul Lee* Advanced Photonics Research Institute (APRI), Gwangju Institute of Science and Technology

(GIST), Gwangju 61005, Republic of Korea

In this talk, I will introduce (1) polar solvent treatment effect on optical properties of the perovskite thin film and (2) enhanced environmental stability of perovskite quantum dots (QDs) by embedding them in polymeric 3D photonic crystals (PCs). In addition, (3) micro-size pattering of perovskite quantum QDs film by PDMS and/or ink-jet printing will be shortly introduced.

The degree of crystallinity and grain size are key parameter to improve luminescence and quantum

efficiency of perovskite LEDs. Herein, we investigated the effects of polar solvent treatment on crystallinity and grain size of perovskite thin film. We confirmed that polar solvent treatment leads to luminance enhancement of organometallic halide perovskite through two simultaneous processes; recrystallization and conversion of unreacted and remained precursors into perovskite.1

The down-conversion perovskite LEDs with a high color purity and a large viewing angle were

realized by utilizing perovskite NP-embedded 3D PCs. The embedded PbBr2 NPs were converted to blue, green and red perovskite NPs via VASP. The angle-dependency of PL emission from perovskite NPs embedded in 3D PCs was significantly improved compared to that of perovskite NPs without photonic structures due to non-directional Bragg scattering induced by the polycrystalline structure of the PC. Furthermore, the perovskite NPs embedded in polycrystalline 3D PCs showed enhanced environmental stability.2

The micro-size pattering of perovskite quantum QDs were conducted by dry contact printing

technique. The resolution of perovskite QDs pattern is ~ 30 micro-meter. The photo-crosslinking of perovskite QDs by ligand modification also conducted to improve solvent resistance.3

(1) S.-H. Chin, J. W. Choi, H. C. Woo, J. H. Kim, H. S. Lee & C.-L. Lee, Nanoscale, 11, 5861 (2019) (2) S.-J. Lee, J. W. Choi, S. Kumar, C.-L. Lee & J.-S. Lee, Mater. Horiz., 5, 1120 (2018) (3) Y.-H. Suh, T. Kim, J. W. Choi, C.-L. Lee & J. Park, ACS Appl. Nano Mater., 1, 488 (2018)

Low Temperature Fabrication of Passivation films by Plasma Enhanced CVD

K. Kamataki, Y. Sasaki, S. Nagaishi, T. Yoshida, K. Abe, H. Hara,

D. Yamashita, N. Itagaki, K. Koga, and M. Shiratani Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan

Email: [email protected]

High nitriding degree silicon nitride (SiN) thin films were deposited at low substrate temperature (100�) by the multi-hollow discharge plasma chemical vapor deposition (CVD). We studied the amount of nanoparticles incorporated into SiN films with three quartz crystal microbalances (QCM). These experimental results show strong relationship between the nitriding degree and the amount and quality of nano-particles incorporated into SiN films. As a result, SiN thin films with high nitriding degree ~ 1.2 -1.3 was obtained at high gas flow ratio N2/SiH4 ~ 300 -500.

1. Introduction Silicon nitride (SiN) is widely used in Si and III-V

electronic and optoelectronic technologies. For example, SiN thin films play an important role in semiconductor devices [1] that include uses as passivation layer to protect semiconductor device and as a gate dielectric layer in thin-film transistors (TFT) [2]. The requirement for SiN thin films have been directed towards improvements of the control of hydrogen concentration, the refractive index and an extinction coefficient of the light etc.

For low temperature formation of SiN films, the plasma enhanced chemical vapor deposition (PECVD) has been mainly used [3-5]. PECVD has the advantage of SiN deposition at ~ 300� though the low-pressure CVD is high temperature technique (>700�). On the other hand, it has disadvantages such as plasma-induced damage and a thermal budget, which may result in active-layer damage or ohmic contact degradation. Recently, there are reports on SiN films by deposition under low substrate temperature conditions at 100� [4] and room temperature [5]. However, available literatures about the relationship between the properties of SiN film and nanoparticles incorporation into the film are very few. In our previous work, we studied about the number of Si nano-particles incorporated into a-Si:H films with three quartz crystal microbalances (QCMs) [6, 7] in PECVD.

Here, aiming to further improvement of the film quality, effects of the nanoparticles incorporation into SiN film on the properties of the film are studied in a multi-hollow discharge plasma (MHDP) CVD using SiH4+N2 mixture gas.

2. Experimental

Experiments were carried out with a MHDPCVD reactor equipped with QCMs [6,7]. Plasmas were sustained in 79 holes of the electrodes. The diameter

and length of the holes are 5.0 mm and 9.8 mm. The powered electrode was connected to a 60 MHz rf power source through a matching network. SiH4 and N2 were fed through the upper side of the reactor, then passed through the holes in the electrodes, and pumped out. The gas flow rate of SiH4 was 10 sccm and of N2 was set in a range of 30 to 120 sccm. The total pressure was 0.5 Torr. The substrate temperature was 55� (= 328 K). The discharge power was 20 W. The deposition time is 1 hour. Nano-particles generated in plasmas were transported towards the downstream region by the gas flow, because their diffusion velocity was less than the gas velocity. Therefore, we can realize a cluster-rich condition in the downstream region. To measure DR and the number of nao-particles

incorporated into SiN films, we employed three QCMs, which were set 20 mm below the lowest electrode, as shown in Fig. 1. The resonance frequency of the quartz crystal decreases with increasing mass deposited on the crystal. The channel A of the QCM was used to measure the DR of radicals and Si clusters (DRtotal). The channel B of the QCM was applied to measure the DR of radicals (DRraidcal) by setting the cluster-eliminating filter above the microbalance. The channel C of the QCM was used as a reference sensor because the resonance frequency of the QCM depends on ambient temperature and pressure.

Fig.1 Configuration of three quartz crystal sensors.

The number of nano-particles incorporated into films is given by the deposition rate ratio R = DRtotal/DRradical. Thus, R shows the amount of nano-particle incorporated into film. In the gas-phase processes simulation [8], main radicals are N, NH, SiH3 in SiH4+N2 remote-plasma activated CVD. 3. Results and Discussion

Figures 3 shows that dependence of (a) deposition ratio DR and (b) nitriding degree N/Si as a function of R (that is the amount of nanoparticle incorporated into film). The amount of nanoparticles incorporated into film R were measured with QCMs under experimental conditions of (SiH4 = 10 sccm, N2 = 30 ~ 120 sccm). The deposition ratio DR increases from 0.1 to 0.5 nm/s with increasing the amount of nanoparticles R. The nitriding degree N/Si tends to increase form 0.4 to 0.7 (e.g. N/Si@Si3N4 = 1.33) with increasing the amount of nanoparticles R. These results show that the amount of nanoparticle incorporated into film has the relationship with the deposition ratio and nitriding degree in this experimental condition. Moreover, these suggest that this relationships link to the quality of nanoparitlces which are produced in plasma phase. We consider that control of property of nanoparticle in plasma contributes to the quality of films in low substrate temperature. Therefore, we focus on control of property of nanoparticles in plasma. In this multi-hollow discharge plasma, it is easy to control mass flow ratio that connects to gas residence time.

To aim to further improvement of the quality of film, SiN films were deposited in condition of large amount of N2 flow (= 100, 300, 500 sccm) and high flow rate N2/SiH4 (SiH4 = 1 sccm) in low substrate temperature 100 � (= 373 K). Figure 3 shows that the nitriding degree N/Si as a function of N2/SiH4 flow ratio. As the amount of N2 flow and N2/SiH4 flow ratio increase, nitriding degree N/Si increases drastically. SiN films with high nitriding degree of about 1.3 was obtained at SiH4 : N2 = 1: 500 sccm. 4. Conclusion � Effects of the amount of nanoparticles incorporated into SiN films with three quartz crystal microbalances (QCM) were investigated. These experimental results show the relationship between the nitriding degree and the amount of nanoparticles incorporated into SiN films, which imply that large amount of N2 flow related to high nitriding degree which corresponded to small R. As a result, SiN thin films with nitriding degree of about 1.3 was obtained at SiH4 : N2 = 1 : 500sccm. References [1] A. K. Sinha, H. J. Levinstein, T. E. Smith, G. Quintana, and S. E. Haszko, J. Electrochm. Soc. 125, 601 (1978). [2] M. J. Powell, B. C. Easton, and O. E. Hill, Appl. Phys. Lett. 38, 794 (1981).

[3] Y. Manabe and T. Mitsuyu et al., J. Appl. Phys. 66, 2475 (1989). [4] H. P. Zhou, D. Y. Wei, L. X. Xu, Y. N. Guo, S. Q. Xiao, S. Y. Huang, S. Xu, Appl. Sur. Sci. 264, 21(2013). [5] H. Zhou, K. Elgaid, C. Wilkinson and I. Thayne, J. J. Appl. Phys.45, 8388 (2006). [6] S. Toko, Y. Torigoe, K. Keya, H. Seo, N. Itagaki, K. Koga, M. Shiratani, J. J. Appl. Phys. 55, 01AA19 (2016). [7] T. Kojima, S. Toko, K. Tanaka, H. Seo, N. Itagaki, K. Koga, M. Shiratani, PFR. 13, 1406082 (2018). [8] M. J. Kushner, J. Appl. Phys. 71(9) 4173 (1992).

Fig.2 dependence of (a) deposition ratio and (b) nitriding degree as a function of R (that is the amount of nanoparticle incorporated into film).

Fig.3 Nitriding degree N/Si as a function of N2/SiH4 flow ratio

Highly transparent solar cells for agrophotovoltaics

Hyunwoong Seo

Department of Energy Engineering, Inje University, Gimhae-si, Gyeongsangnamdo, Korea

* [email protected]

ABSTRACT

Korean government is carrying forward the policy of renewable energy 3020 that the proportion of renewable

energy generation will increase upto 20% by 2030. Especially, they focus on solar and wind power because 74%

of Korean renewable energy was based on non-environmental-friendly waste & bio energy at the start point of

this policy. To achieve the final goal, they presented some main projects such as small-scale photovoltaics of

house or building, marine photovoltaics and wind power, and farm photovoltaics. As farm photovoltaics,

agrophotovoltaics (APV) has recently attracted much attention for environmental-friendly and economical

electricity. APV conducts farming or agriculture with power generation and its concept is shown in figure

proposed by Fraunhofer ISE. It is possible to contribute to realize the above governmental policy ‘renewable

energy 3020’. However, conventional APV has used opaque or untransparent solar cells, resulting in the

reduction of incident light and the decrease in crop yields. Proposal from Fraunhofer ISE also expected 80% of

power generation and crop yields in comparison with uncombined case. In order to solve the limitation of

conventional APV, this work introduces highly

transparent solar cells. Transparent solar cells lead to

the increase in incident light and the increase in crop

yields, resulting in more effective APV. Here, dye-

sensitized solar cells (DSCs) were used for

transparent APV. DSC is one of very transparent

solar cells, but its transmittance is not enough for

APV. One of obstacles is untransparent or

reflectional Pt electro-catalyst. Therefore, this work

proposed Pt-free DSC based on transparent

polymeric electro-catalyst. Polymer electrocatalyst

meets the requirement of Pt-free electrocatalytic

materials such as the chemical and physical

stabilities, electrocatalytic activity, and electrical

conductivity. Proposed Pt-free electrocatalysts was

analyzed in aspects of the electrocatalytic and

electrical properties. Detailed results and analysis

will be presented on the site.

KEYWORDS

Agrophotovoltaics, Transparent solar cell, Dye-sensitized solar cell, Pt-free electrocatalyst.

Figure. The concept of Agrophotovoltaics

Analysis and Control of Surface Reaction in Plasma Enhanced Atomic Layer Etching Processes

Takayoshi Tsutsumi

Center for Low-Temperature Plasma Sciences, Nagoya University

Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8603 Japan

Atomic layer etching (ALE) is focused on for nanoscale devices manufacture because it enables

precise etched thickness, high controllability, and less damage than that with conventional plasma etching.

An atomic layer etching is a cyclic process that involves two steps: etchant gas adsorption or etchant film

deposition on a target material, followed by removal of the layer reacted with the etchant species. We

introduce the experimental about the surface reaction in two kinds of ALE process.

As first ALE process, chlorine is used as an etchant gas for the chlorination of the GaN surfaces.

The chlorination surface is removed by an energetic species, such as accelerated Ar ions. To realize this

process, full understanding of surface reactions in each cycle step is required to elucidate the Cl adsorption

on the Ar ion bombarded GaN surface using the beam experiments and the in situ X-ray photoelectron

spectroscopy (XPS). The results indicated that Ar ion irradiation formed the Ga rich damaged layer,

consisting of an interatomic mixing of Ga, N and Cl with relatively deep depths. After the Cl exposure, the

component for Ga-Ga decreased, and the component for Ga-Cl increased. Chlorinated layer thickness

relates to damaged layer thickness due to Ar ion bombardment. As a result, the etched depth was

predominantly determined by the damaged layer thickness.

As second ALE process, the deposition of fluorocarbons as an etchant film was developed for ALE

of SiO.[1] Fluorine atoms in the fluorocarbon film form SiFx products by Ar ion bombardment, while the

carbon atoms react with oxygen atoms to generate gas phase COx molecules. However, the excess carbon

atoms form the carbon-rich film on the SiO2 surface. Moreover, the residual fluorocarbon film on the

walls enter the gas phase during Ar plasma. These induce a change in the plasma conditions and the

etching rate per cycle (EPC). To avoid excess carbon atoms in the fluorocarbon film, an ALE process for

SiO2 was developed by alternating O2 plasma etching and fluorocarbon film deposition.[2] O2 plasma

induces an etching reaction between the fluorocarbon and SiO2, while the surface condition is

simultaneously maintained through evaporation of the excess carbon as COx products. Therefore, the ALE

based on O2 plasma has high controllability and low variability.

In the symposium, the author introduces issues and requirements and discuses control of the surface

reaction in the above ALE processes.

References

[1] G. Oehrlein et al., ECS J. Solid State Sci. Technol. 4, N5041 (2015).

[2] T. Tsutsumi et al., J. Vac. Sci. Technol. A 35, 01A103 (2017).

Review of new energy harvesting from unused energy resources

Joo-Hyung Kim*, Jihyun Kim, Youngjun Lee, Kyeongho Shin and Gwangwook Hong

1. Lab. of Intelligent Devices and Thermal Control, Dept. of Mechanical Eng., Inha University, inharo-100, Namgu, Incheon, 22212 South Korea

(*: corresponding author, email: [email protected])

Abstract

Renewable Energy or Unused Energy is very attractive one to be utilized for specified mission based energy resources in Earth as well as Space Technololgies. From small energy scavenging to some mobile energy source, we reviewed and demonstrated some feasible applicable techniques for novel energy resources. Theses novel approaches, including body heat energy generations, solar concentrated booster, water vaporized motors, single crystal SiGe based thermoelectric energy harvesting, electro-hydro dynamics, binary/ternary refrigerant based organic Rankine cycles and static charger can be discussed and suggested as potential applicable methods.

Dye-Sensitized Photo Rechargeable Battery for Power Source of Internet of Things

Tae-Hyuk Kwon

Department of Chemistry, Ulsan National Institute of Science and Technology, Ulsan, 689-798, Republic of Korea Ulsan, 689-798, Republic of

Korea Email : [email protected]

Dye-Sensitized Solar Cells (DSSCs) have great potentials owing to their aesthetic colors, transparency and low cost. Furthermore, they are favorable for indoor system, because DSSCs have great power conversion efficiency (PCE) at low light. However, there are still several problems in the practical applications. Therefore, our group suggested the new concepts of organic materials and devices for approaching to real application. For this aim, we developed dye-sensitized photo rechargeable solar battery for indoor light saving.

Until now, most of single-structured photo-rechargeable devices considered photo-charging process at high light intensity (mainly standard AM 1.5G sunlight). Furthermore, it is very difficult to combine dye-sensitized solar cells with lithium ion battery in a monolithic device because of their intrinsic mismatch energy levels of photo (-0.5 V vs NHE) and storage electrode (-3.0 V vs NHE). We came up with this intrinsic issues by using the overlithiation reaction of LiMn2O4 (ca. 0.0 V vs NHE) for energy storage and finally, achieved self-powered dye-sensitized photo rechargeable solar battery (DSPB, FTO/TiO2/Dye/Redox mediator/Pt-Li+ conducting separator/Li+ solution/ LixMn2O4) in monolithic devices, and suggested new concepts for energy recycle of indoor lightening. Next, we investigated the light intensity dependence of photo-charged energy density with different redox mediator (or charge regenerator for oxidized dye), such as I−/I3−, Co2+/3+(bpy)3, Cu+/2+(dmp)2. Finally, the DSSBs were successfully working at low light intensity (11.5% of ηoverall at 0.15 mW cm−2 (500 lux)), operating the commercial IoT wireless sensor node using only indoor light sources.

Solar-driven water splitting for eco-friendly hydrogen production :challenges and perspectives

Min-Kyu Sona,*, Tatsumi Ishiharaa

aInternational Institute for Carbon-Neutral Energy Research, Kyushu University, Fukuoka, Japan *[email protected]

Solar-driven water splitting is a promising and sustainable route for producing hydrogen because the solar energy is enormous and semi-permanent and its by-products are only hydrogen and oxygen without any carbon-based materials. There are three kinds of techniques for solar-driven water splitting: particulate photocatalytic system, photoelectrochemical (PEC) system and photovoltaic (PV)-electrolyzer [1]. Particulate photocatalytic system is simple and easily scalable, but its efficiency is low below 1 %. On the other hand, PV-electrolyzer shows the high performance, but the system is quite complicated and expensive. PEC water splitting system can overcome these disadvantages: its performance is higher than particulate photocatalytic system, while it is simpler than PV-electrolyzer.

PEC photocathodes based on p-type semiconductors are the main part for generating hydrogen in the PEC water splitting system. It generates excited charges by absorbing the sunlight and the hydrogen is produced by electrons via the water reduction reaction at its interface with the water. We should consider three main factors for the practical application of PEC photocathodes: efficiency, stability and scalability. Efficiency should be higher than a solar-to-hydrogen (STH) efficiency of 10% because it is the minimum efficiency for the commercialization. Stability is also a critical factor for the durable PEC water splitting because the most semiconductors are unstable in the water. Hence, they easily loses their PEC performances, leading to the failure of long-term operation. Scalability should also considered for the mass production of hydrogen because all of the highest efficiency records are based on the lab scale size below 1 cm2, which is not enough for the commercialization.

In this talk, the research progresses on the PEC photocathodes are introduced focusing on these three factors. Cuprous oxide (Cu2O) is a promising p-type semiconductor for the efficient PEC photocathode because it theoretically generates a photocurrent density of 14.7 mA/cm2 that corresponds to a STH efficiency of 18 %. Several techniques to improve the PEC performances of the Cu2O photocathode are introduced [2-4]. However, it needs the protection layer for preventing its degradation in the water due to its poor stability. We suggest lanthanum iron oxide (LaFeO3) and copper iron oxide (CuFeO2) as alternative p-type semiconductors for durable PEC water splitting because they are ternary oxide materials, which are more robust in the water than binary oxide materials [5,6]. We characterize the properties of the sputtered LaFeO3 thin film and the electrodeposited CuFeO2 thin film for the PEC photocathode, in terms of the stability. Finally, we briefly talk about the effort on the large-scale PEC photocathodes toward the practical PEC water splitting in the future.

[1] J.H. Kim et al., Chem. Soc. Rev. 48 (2019) 1908-1971. [2] L. Pan et al., Nature Catalysis 1 (2018) 412-420. [3] M.K. Son et al., Energy Environ. Sci. 10 (2017) 912-918. [4] J. Luo et al., Nano Lett. 16 (2016) 1848-1857. [5] G.S. Pawar et al., Scientific Reports 8 (2018) 3501. [6] M.S. Prevot et al., ChemSusChem 8 (2015) 1359-1367.

Enhancing Solid-State Emission of Graphene-like Nanostructures by Edge-Fenced Functionalization

Hye Jin Choa, Sangwon Kimb, Sangback Leec, Yeonjoo Job, Juhyen Leea, Yunmi Leec, Hyunjin Shinb, and Changsik Song*a

aDepartment of Chemistry, Sungkyunkwan University, Suwon, Gyeonggi 16419 Korea. bSamsung Advanced Institute of Technology, 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do, 16419,

Republic of Korea. cDepartment of Chemistry, Kwangwoon University, 20 Kwangwoon-ro, Nowon-gu, Seoul, 01897, Republic of Korea.

*Corresponding author e-mail: [email protected].

Polycyclic aromatic hydrocarbons (PAHs) refer to aromatic molecules composed of only C

and H, having flat structures in most cases. PAHs are promising for material science, based on their high thermal and chemical stability, electron and hole mobility, and unique photophysical characteristics. However, the PAHs have limitations in applications due to the low solution processability. The strong π-π interaction between the aromatic rings of PAHs forces single molecules to aggregate. Many researchers have reported about solubilizing PAHs in various ways – typically classified into edge functionalization or contorting the structure. Herein, we report an effective way to suppress the π-π stacking of PAHs with steric hindrance. A bulky 2,6-dimethylphenyl group, which is defined as the “picket-fence group” in this work, was introduced on the edge of the PAHs to exert steric repulsion. Several compounds based on triphenylene, pyrene, coronene, and hexabenzocoronene (HBC) were synthesized by bottom-up synthesis to control the structure precisely. Further investigation to figure out the effect of steric repulsion for π stacking inhibition, the “picket-fence effect”, was proceeded through UV-Vis absorption, photoluminescence (PL), powder-X ray diffraction (pXRD) analysis and calculation. We could conclude that the picket size, the PAH size, and the shape of the edge structure of PAH in combination played an essential role in adjusting the picket-fence effect. To the best of our knowledge, this is the first time to have an in-depth investigation of the steric effect on π stacking inhibition, resulting in excellent solid-state photophysical properties.

Development of high sensitive gas sensor and magnetic Hall sensor using III-V

compound semiconductors

Kyung-Ho Park

Device Technology Division, Korea Advanced Nano Fab Center (KANC), Suwon 16229, South Korea

(e-mail : [email protected])

III-V compound semiconductor materials exhibit superior properties compared to Si in many aspects. For example, AlGaN/GaN HEMT (high electron mobility transistor) heterostructure shows the extremely sensitive nature of the adsorption of analytes on gate surface, and GaAs has a very high electron mobility of 8,500 cm2/V·s. Using these two compound semiconductor material systems, we developed AlGaN/GaN HEMT gas sensor and GaAs magnetic Hall sensor platforms. A hydrogen sensor was fabricated using a conventional HEMT fabrication process with a thin Pt-

layer as a sensing material and gate contact. Compared to other electrical resistance-based sensors, HEMT, as a type of field effect transistor, sensors have the advantage of adjusting the gate bias to optimize the sensitivity. A HEMT sensor with Pt-gate thickness of 10 nm, gate length (Lg) of 20 µm and channel width (Wg) of 6 µm showed the current change of 6×109 % at gate voltage -6V when it is exposed 0.5% H2 at room temperature. To the best of our knowledge, it is the highest sensitivity [(IH2 – IN2)/ IN2 ×100 %] result of hydrogen detection.

The GaAs magnetic Hall-effect sensors were fabricated using GaAs/InGaP/GaAs epitaxy structure

grown on 6-inch semi-insulating GaAs wafer. The fabricated Hall sensor has a typical size of 235um x 235um and the length (L) and width (W) ratios of input channel were changed from 1.3 to 2 in 0.5 steps. As an increase of L/W ratio of Hall sensor chip, the Hall voltage was decreased linearly. The typical Hall voltage of L/W ratio 1.3 and 2 chips showed ~115 mV and ~90 mV under the measurement conditions of a magnetic field of 500 G and an input voltage of 6 V (an input current of ~3mA), respectively. We also studied the effect of the reduction of the Hall sensor chip size.

We will discuss more detailed fabrication methods and sensing characteristics of HEMT gas sensors

and magnetic Hall sensors at the conference.

mailto:[email protected]

Trapping of photons and enhancement of nonlinear

optical effect in SiC-based photonic crystal nanocavities

Bong-Shik Song*

Department of Electrical and Computer Engineering, Sungkyunkwan University, Suwon 16419, Korea

*E-mail: [email protected]

Semiconductors-based photonic crystal nanocavities, which can confine strongly photons in a

few cubic wavelengths, have been studied much for scientific and engineering applications

such as trapping of specific photons, strong optical couplings, enhancement of nonlinear optical

effects, and ultra-small and integrated photonic chips. In particular, SiC-based photonic crystal

nanocavities have been attracting much interest because SiC exhibits wide electronic bandgap

of 2.2~3.2 eV, high thermal conductivity, and second-order nonlinear optical coefficients. In

this symposium, the fundamentals of design, fabrication, and optical properties of SiC-based

photonic crystals are presented. In addition, superior characteristics of SiC-based photonic

crystals to those of conventional semiconductors (Si or GaAs) are presented: suppression of

multiple photon absorption at high photons intensity, thermal stable operation for

environmental temperature change, ultrabroadband operation from infrared to visible

wavelengths in integrated photonic devices, and representative nonlinear optical effect of

second harmonic generation (SHG). Furthermore, recent progress of SiC photonic crystals are

presented for reduction of optical loss in SiC layer, achievement of ultrahigh–Q factors, and

enhancement of SHG. These results will pave the way for opening SiC photonics and lead to

promising applications such as ultra-broad band integrated photonics, cavity quantum

electrodynamics, and highly efficient wavelength conversions, quantum light sources by

employing unique states of the SiC material.

References

[1] B. S. Song, S. Noda, T. Asano, and Y. Akahane, Nat. Mater. 4, 207 (2005)

[2] Y. Uesugi, B. S. Song,T. Asano, S. Noda, Opt. Express 14, 377 (2006)

[3] B. S.Song, S. Yamada, B. S. Song, T. Asano, and S. Noda, Opt. Express 19, 11084 (2011)

[4] S. Yamada, B. S. Song, J. Upham, T. Asano,Y. Tanaka, and S. Noda, Opt. Express 20,

14789 (2012)

[5] S. Yamada, B. S. Song, T. Asano, and S. Noda, Appl. Phys. Lett. 99, 20 (2011)

[6] S. Yamada, B. S. Song, T. Asano, and S. Noda, Opt. Lett. 36, 3981 (2011)

[7] S. Yamada, B. S. Song, S. Jeon, J. Upham, Y. Tanaka, T. Asano, and S. Noda, Opt. Lett.

39, 1768 (2014)

[8] S Jeon, H Kim, B. S. Song, Y. Yamaguchi, T. Asano, and S. Noda, Opt. Lett. 41, 5486

(2016)

[9] H. Kim, S. Jeon, and B. S. Song, J. Opt. Soc. Am. B 33, 2010 (2016)

[10]B. S. Song, S. Jeon, H. Kim, D. Kang, T. Asano, and S. Noda, Appl. Phys. Lett. 113,

231106 (2018)

[11]H. Kim, D. Kang, and B. S. Song Opt. Lett. 44, 1837 (2019)

[12]B. S. Song, T. Asano, S. Jeon, H. Kim, C. Chen, D. Kang, and S. Noda, Optica 6, 991(2019)


D-NDR Device based on hybrid 2D vdW/organic heterostructure

Keun Heo, Jin-Hong Park* Department of Electrical and Computer Engineering, Sungkyunkwan University

Recently, combinations of two-dimensional van der Waals (2D vdW) materials and organic

materials have attracted attention because they facilitate the formation of various

heterojunctions with excellent interface quality owing to the absence of dangling bonds on their

surface. In this paper, we report a double negative differential resistance (D-NDR)

characteristic of a hybrid 2D vdW/organic tunneling device consisting of a hafnium

disulfide/pentacene heterojunction and a three-dimensional pentacene resistor. This D-NDR

phenomenon was achieved by precisely controlling an NDR peak voltage with the pentacene

resistor and then integrating two distinct NDR devices in parallel. Then, we demonstrated the

operation of a controllable-gain amplifier configured with the D-NDR device and an n-channel

2D vdW transistor using the Cadence® Spectre® simulation platform. The proposed D-NDR

device technology based on a hybrid 2D vdW/organic heterostructure provides a scientific

foundation for various circuit applications that require the NDR phenomenon.

Engineered heterojunction for high-performance optoelectronic devices

Sangyeon Pak, SeungNam Cha* Department of Physics, Sungkyunkwan University

Email: [email protected]; [email protected]

Semiconductor heterostructures with different electronic band gap energies and electron affinities have long been of considerable interest for both fundamental condensed matter physics and potential applications in modern electronics and optoelectronics as well as energy conversion systems. Recently, notable progress in the field of heterostructures has been made resulting in the development of high performance, high speed, and high power devices through improvements in the experimental technique and the theoretical understanding. Moreover, to open up new avenues beyond the limit of conventional bulk semiconductor structures, many efforts have been focused on developing new semiconducting nanomaterials as well as understanding the various underlying physical phenomena that occur at the heterojunction interface. These in turn allow for the creation of new device and structure concepts with unique functionality, which is particularly relevant to the development of next-generation flexible and wearable device applications.

In this talk, I will discuss various ways to engineer heterojunctions based on nanostructured materials for designing high-performance optoelectronic devices. They are achieved by employing nanostructured materials such as 2D transition metal dichalcogenides and PbS quantum dots and various surface modification/band structure engineering techniques. These findings present an important pathway toward designing heterostructures and their optoelectronic devices.

Heat transfer enhancement of thermal interface materials with ZnO tetrapod structure

Kyeongho Shin, Jihyun Kim and Joo-Hyung Kim,*

Lab. of Intelligent Devices and Thermal Control, Dept. of Mechanical Eng., Inha University, inharo-100, Namgu, Incheon, 22212 South Korea

(*: corresponding author, email: [email protected])

Abstract

The surface condition and heat transfer coefficient of the thermal interface layer (TIM) are mainly related to the energy efficiency of whole system. The energy conversion via heat transfer will be restricted by the thermal properties of TIM. Heat transfer is very important phenomena to transport the thermal energy from a heat reservoir to another one. In this paper, simulation and experimental data of TIM mixed with nano-sized ZnO tetrapod structures in were investigated. From the simulation data, the volume contents of ZnO tetrapod in TIM was compared and further thermodynamic behavior also is evaluated.

Si3N4/Carbon based PEDOT:PSS Counter Electrode for low-cost Dye-Sensitized Solar Cells.

F. L. Chawarambwa1, E. T. Putri1, Y. Hao1, Hyunwoong Seo2, Min-Kyu Son1, Kunihiro Kamataki1, Naho Itagaki1, K. Koga1, M. Shiratani1

1Kyushu university, Japan 2Inje University，Korea

E-mail: [email protected]

Poly (3, 4-ethylenedioxythiophene) : poly (styrene sulfonate) (PEDOT:PSS) is a well-known conductive

polymer that is often used as a counter electrode (CE) in dye-sensitized solar cells (DSSC). PEDOT:PSS is highly

favoured due to its high transmittance and conductivity [1]. Low electrocatalytic activity of PEDOT:PSS results in

low fill factor and low overall cell conversion efficiency. In order to solve the problem of low catalytic activity in

the PEDOT:PSS counter electrode, PEDOT:PSS composites have been developed. The general idea is to find a

material that when mixed with PEDOT:PSS, will enhance the catalytic performance of the PEDOT:PSS counter

electrode. In composites of Si3N4, graphene nanoplatelets and carbon black are mechanically mixed with

PEDOT:PSS to form new PEDOT:PSS composite solutions.

Initially, 1 wt% Triton X-100 (Sigma Aldrich), 8 wt% DMSO (Yoneyama) and 1 ml Clevious pH-1000

PEDOT:PSS (Heraeus) are mixed on a ceramic magnetic stirrer for 24 hours to form a stable uniform mixture

(PEDOT:PSS/DMSO/Triton X-100). Graphene nanoplatelets (GNP), carbon black (CB) and Si3N4 1:1 weight

composition ratio composite was prepared by mixing with a conditioning mixture (AR-100 Thinky) at 400 rpm

for 2 minutes to form a uniform composite mixture of GNP/Si3N4 and CB/ Si3N4 nanoparticles. The composite

nanoparticles were then added to the 1 ml PEDOT:PSS/DMSO/Triton X-100 solution mixture separately and

mixed with a conditioning mixture at 1000 rpm and 400 rpm for 10 and 5 minutes respectively to form uniform

solution-mixtures of PEDOT:PSS/X-Triton/GNP/Si3N4 and PEDOT:PSS/X-Triton/CB/Si3N4. Uniform films were

obtained after the solution-mixtures were spin-coated on clean FTO glass at 4000 rpm for 60 seconds. The

counter-electrodes were subsequently annealed at 120 C for 10 minutes and allowed to cool in air. Figure 1 shows the efficiencies of the developed counter electrodes at various nanoparticle concentrations

plotted against platinum and PEDOT:PSS CEs. The graph shows that there is

a sharp increase in cell efficiency with the introduction of the composite

nanoparticles to PEDOT:PSS. The DSSC with

PEDOT:PSS/X-Triton/CB/Si3N4 CE showed a peak cell efficiency of 5.56%

while the DSSC with PEDOT:PSS/X-Triton/GNP/Si3N4 showed a peak cell

efficiency of 5.52%. Both results are better that those of platinum (5.24%).

The addition of nanoparticles increases the conductivity as well as the surface

area of PEDOT:PSS. At the same time, addition of Triton X-100 increases the

adhesion between PEDOT:PSS and the FTO glass. This is because X-Triton

transforms PEDOT:PSS capsule into a nanofibril structure. As a result, the

electrocatalytic activity of PEDOT:PSS is enhanced resulting in high electron

injection and high electron transportation in the cell.

[1] H Seo, et al., Progress in Photovoltaics: Research and Applications 26 (2018) 145.

3.5

4

4.5

5

5.5

0 20 40 60 80 100 120 140

PtPEDOT:PSSCB/Si

3N

4

GNP/Si3N

4

Effe

cien

cy [%

]

Concentration [mg] Fig.1. Efficiencies of the developed

CEs.

Study of Energy-Delay Sensitivity of Ferroelectric Capacitor-gated NEM Relay

Chankeun Yoon, Changhwan Shin

* Dept of Electrical and Computer Engineering, Sungkyunkwan University *Corresponding: [email protected]

The transistors in integrated circuits (ICs) have been aggressively scaled down to improve the transistor

performance and the functions of the ICs. However, this results in the increased off-state leakage current (Ioff) of the transistor even when the IC transistors are turned off. Since the IC comprises billions of transistors, the energy consumption in the off-state may drastically increase. This hampers the scaling of the power supply voltage (VDD). Therefore, an appropriate technology to reduce the Ioff is of particular importance. Ioff can be theoretically suppressed by (i) increasing the threshold voltage (Vth) or (ii) decreasing/improving the subthreshold slope (SS), which is the gate voltage (VGS) that is required to increase the drain current (IDS) by 10 times. However, increasing the Vth results in a reduced on-state drive current (Ion). In addition, SS is limited to 60 mV/decade at the room temperature (a.k.a, the Boltzmann limit). To address this issue, various steep switching devices, which exhibit an sub-60 mV/decade of SS, have been proposed [1]-[3]. These steep switching devices can achieve reduced Ioff and static power consumption because their SS is less than 60 mV/decade at 300 K. Among these devices, the nanoelectromechanical (NEM) relay has received significant attention because it has almost zero SS and negligible Ioff [4]. Recently, several studies have suggested that the operating voltage and electrical characteristics of an NEM relay can be reduced/improved by connecting it in series with a ferroelectric capacitor [5], [6]. The concept of the series-connected structure, i.e., “the NEM relay + ferroelectric capacitor,” originates from voltage amplification, generated by the negative capacitance (NC) phenomenon in a ferroelectric capacitor. In a previous study, the improved energy-delay properties of an NEM relay with the NC of a ferroelectric capacitor (NC + NEM relay) when compared with those of the NEM relay were investigated [7]. This improvement can be attributed to voltage amplification. However, there is a critical point, where the energy-delay properties of the NC + NEM relay begin to deteriorate compared to those of the NEM relay. In this study, a device design guideline is proposed to improve the energy-delay properties and operating voltage of the NC + NEM relay compared to those of the conventional NEM relay using sensitivity analysis.

[1] W.Y. Choi et al, IEEE Electron Device Lett., 28, 8 (2007) [2] N. Shukla et al, Nat. Commun., 6, 7812 (2015) [3] S. Salahuddin et al, Nano Lett., 8, 2 (2007) [4] R . Nathanael et al, Proc. IEEE IEDM, (2009) [5] M. Masuduzzaman et al, Nano Lett., 14, 6 (2014) [6] K.Choe et al, IEEE Trans. Electron Devices, 64, 12 (2017) [7] I-R. Chen et al, IEEE Electron Device Lett., 36, 9 (2015)

Fig. 1. Simulated sensitivity to beam length (left) and sensitivity to beam thickness (right) of the NEM relay and NC + NEM relay


Effects of Activated Carbon Counter Electrode

On Bifacial Dye Sensitized Solar Cells (DSSCs)

Tika Erna Putri1, Yuan Hao1, , Fadzai Lesley Chawarambwa1,

Hyunwoong Seo2, Min-Kyu Son1, Kunihiro Kamataki1, Naho Itagaki1,

Kazunori Koga1, and Masaharu Shiratani1

Dept. of Electronics, Kyushu University, Japan

Dept. of Energy Engineering, Inje University，Korea

[email protected]

Keywords: Bifacial Dye Sensitized Solar Cell, Activated Carbon, Counter Electrode

Abstract. The losses of solar cells are consisted of electrical losses and optical losses. Optical losses

chiefly effect the power from a solar cell by lowering the short-circuit current. The optical path length

in the solar cell may be increased by a combination of surface texturing and light trapping.

So far we have developed several methods to enhance efficiency of various solar cells. Here we apply

bifacial Dye Sensitized Solar Cell (DSSC) to increase light absorption and output power of DSSC.

We have employed Activated Carbon (AC) as a low cost counter electrode, an alternative to Pt

counter electrode. Bifacial with AC counter electrode showed efficiency of 4.77% compared to

bifacial using Pt counter electrode of 6.56% at an angle of 45o. Addition of AC with Dimethyl

Sulfoxide (DMSO) increases the efficiency of AC to 5.52%. Addition of AC with Titanium

Carbonitride (TiCN) increases the efficiency of AC to 5.23%. These results indicate that AC has the

potential to replace Pt at the counter electrode of bifacial DSSCs.

References:

[1] H.J. Kim, et al., Energies 11 (2018) 1931.

[2] H Seo, et al., Progress in Photovoltaics: Research and Applications 26 (2018) 145.

[3] H.J. Kim, et al., Journal of Electroanalytical Chemistry 788 (2017) 131.

Low-temperature, chemical vapor deposition synthesis of MoS2 monolayer

Seungje Kim, Sangyeon Pak, SeungNam Cha*

Department of Physics, Sungkyunkwan University

Low-temperature synthesis of 2D materials is of high importance for their implementations for future flexible and transparent devices. However, to date, low-temperature synthesis of MoS2 monolayer based on chemical vapor deposition method has been rarely investigated. In this presentation, we discuss novel and simple method to grow MoS2 monolayers using CVD at below 500 ˚C.

Nanoparticles Synthesis of Cubic Rock-Salt Lithium Oxide Composite

with Refractory Metal for Lithium-Ion Battery Electrodes

Tadashi Nonaka, Manabu Tanaka, Takayuki Watanabe

Department of Chemical Engineering, Kyushu University, Japan Attractive material processing with thermal plasmas have been widely proposed for the

nanoparticles synthesis at a high productivity [1]. This is because thermal plasmas offer unique advantages such as high enthalpy, high chemical reactivity, rapid quenching rate, and selectivity of reaction atmosphere.

Lithium metal oxides, as electrode materials, have attracted many researchers in the field of lithium-ion batteries (LiB). Lamellar rock-salt type LiCoO2 is widely employed as cathode materials in commercial batteries in spite of its toxicity and high cost. Therefore, alternative materials are strongly required. Control in crystal structure of the lithium metal oxide is essential to enhance the battery characteristics. Cubic rock-salt type Li3NbO4 was examined as high-capacity cathode materials for LiB [2]. Iron doping improves Li ion diffusion performance without changing the cubic rock-salt structure. The purpose of this study is to synthesize cubic rock-salt type Li-Nb-Fe oxide nanoparticles by induction thermal plasmas.

The induction thermal plasma consists of a plasma torch, a synthesis chamber, and a filter. The plasma was generated with Ar and O2 by RF power supply of 4MHz under atmospheric pressure. Input power was 20 kW. Raw materials mixed of Li2CO3 (3.5 µm), Nb (20 µm), and Fe (5 µm) were introduced into the plasma at a feed rate of 0.3 g/min. Li-Nb-Fe system with different composition ratios of 3:1:1, 2:1.5:0.5, 2:1:1, and 2:0.5:1.5 were prepared to clarify the effect of the mole fraction of Li, Nb, and Fe on the crystal structure of the products.

Synthesized nanoparticles were characterized by X-ray diffraction in Fig. 1. Results showed that Cubic-rock salt type (Fm-3m) as target product was successfully synthesized in all conditions. Cubic-rock salt type was most synthesized at Li:Nb:Fe = 3:1:1.

The formation mechanism of cubic rock-salt type Li-Nb-Fe oxide nanoparticles were revealed on the basis of the nucleation theory [3]. The estimated nucleation temperature of Nb was 3012 K, which is the highest nucleation temperature in Li-Nb-Fe system. therefore, Nb nucleates first, and then Li2O and Fe vapors co-condense on the nuclei. Consequently, the cubic rock-salt type Li- Nb-Fe oxide nanoparticles are formed. In conclusion, Thermal plasma synthesis enables to produce attractive electrode materials for lithium-ion battery at high-productivity. [1] N. Yabuuchi, et al., Proc. Natl. Acad. Sci. USA., 112 (25) 7650-7655 (2015) [2] M. Shigeta and A. B. Murphy, J. Phys. D: Appl. Phys. 44 (2011) [3] S. L. Girshick et al., Aerosol Sci. Technol., 13, 465-477 (1990)

Fig.1. XRD spectra of nanoparticles

in Li-Nb-Fe system.

Effect of Ligands in Colloidal Transition Metal Dichalcogenides as Catalyst for Hydrogen Evolution Reaction

Meeree Kim1, 2 and Hyoyoung Lee1, 2, 3, 4* 1Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan




Hydrogen evolution reaction (HER) which involves the electrolysis of water molecules has been attracted as a clean synthesis of hydrogen, which is an alternative to steam methane reformer widely used in industry [1]. Among earth-abundant catalysts, promising candidates are transition-metal dichalcogenides (TMDs), which are two-dimensional (2D) layered materials; they can reach high current densities at low over-potentials [2]. Generally, these materials have been synthesized by vacuum-involving method like chemical vacuum deposition (CVD), while a colloidal synthesis has been less focused in spite of its scalable, less energy-intensive and cost-effective advantages [3]. The main reason is the existence of the surface ligands on the materials, resulting in the intrinsic limitation for a wide use as catalysts. Therefore, understanding the surface chemistry of colloidal nanocrystals (NCs) becomes the key factor to overcome their limitations as catalysts.

The surface chemistry in colloidal synthesis and surface stabilization of NCs has been well-developed and established experimentally over the past 30 years. The surface ligands have been known to saturate dangling bonds to stabilize surface energy and affect to the reaction mechanism in synthesis by kinetic and thermodynamic controls as well [4]. However, detailed understanding on this ligand chemistry of NCs are largely focused on the ionic II-VI (CdSe, CdS) and IV-VI (PbS, PbSe) semiconducting NCs. Understanding of ligand chemistry in 2D TMDs has been considered to be challenging because of their additional covalency requiring a high growth temperature and complicated by large anisotropy in 2D layered structure.

In this presentation, we investigate the influence of surface ligands in both of colloidal synthesis and ligand exchange of tungsten diselenide, WSe2. While understanding the ligand chemistry on the surface of NCs becomes important, the existence of counter-cations not binding to the core NCs but charge-balancing the surface of NCs gives complexity to understand NCs in the solid-state applications. Therefore, in ligand exchange, the role of counter-cations has been rarely studied and even ignored by intentionally using molecules with low thermal stability. We report the effectiveness of existing counter-cations in ligand exchange to enhance HER activity of colloidal TMD material, WSe2 (Figure 1). Our experimental results show that exchanging surface functionalities with S2- anionic ligands enhance HER kinetics while the existence of intercalated counter-cations improves the charge transfer with electrolyte. Furthermore, effect of dual-ligands consisted of two different types of ligands, halides and amines, in colloidal synthesis is also discussed. We found that the ratio between different types of ligands (according to the number of electrons involved) affects to the amount of each phase existing in 1T’-2H mixed WSe2. The photocurrent density shows a correlated tendency, resulting in the importance of phase control in photo-electrochemical catalyst. Based on the observations, we conclusively demonstrate that ligand control is required to synthesize the desired phase in colloidal TMD NCs.

[1] N. Udengaard, Prepr. Pap.-Am. Chem. Soc., Div. Fuel Chem. 49, 906 (2004). [2] C. G. Morales-Guio et al, Chem. Soc. Rev., 43, 6555 (2014). [3] D. A. Henckel et al, ACS Catal., 7, 2815 (2017). [4] M. A. Boles et al, Nat. Mater., 15, 141 (2016).

Fig. 1 LSV for ligand-exchanged colloidal WSe2

Improvement of wool surface charging properties by plasma surface modification process

T. Moriyama1), T. Tsutsumi2), H. Kondo2), M. Sekine2), K. Ishikawa2), and M. Hori2)

1) Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8603 Japan

2) Center for Low-Temperature Plasma Sciences, Nagoya University,

Furo-cho, Chikusa-ku, Nagoya, 464-8603 Japan

Fabrics are used for fabricating of the clothing. Wool fiber is excellent in heat-insulation, high

breathability, and moisture permeability attributed to the micro structure unique to wool. [1-3] Wool fiber

consists of a stratified stack of two tissue layers. The outside tissue is hydrophobic as called “cuticles” and

the inside layer is hydrophilic as called “cortex”. Low electrical conductivity of the wool fabrics induces to

build up electrostatic charges by friction with chemical fibers, such as polyester. To improve the

chargeability, plasma sputtering of gold nanoparticles onto wool fabrics is a candidate technique for the

fabrics surface treatment without damage to this microstructure. In this study, we demonstrate the effect of

the sputtered nanoparticles on relaxation of the electrostatic charges on the wool fabrics.

The sample wool clothes were divided into 1 cm square and attached on Si substrate surface by carbon

tapes. Gold nanoparticles were sputtered on them by changing processing times for 2, 6, and 10 min. The

morphological observations of the sputtered surface were conducted using scanning electron microscope

(SEM). Samples were built up electrostatic charges by rubbing with a polyester cloth for 2 minutes. The

rubbing test was carried out in the glove box under controlling temperature at 23.2°C and 10% relative

humidity. Charged potential was measured using a non-contact type surface potential meter.

The cuticle structure was not destructed by the

sputtering. In the sample for the 10-minutes sputtering,

however, the surface smoothing was observed. Fig. 1 shows

the dependence of the charged potential on the sputtering

time. The result indicated that change in the amount of

electrostatic charge depends on sputtering time. As the

amount of gold deposited increases, the charge amount

sharply decreases. To compare initial and 10 minutes, charge

amount decrease by 85%, from 781 to 115 V. From these

results, it was found that the attachment of gold nanoparticles by sputtering was effective for suppressing

the charging of wool.

References

[1] S. Kawabata, Journal of Textile Engineering 39, T184 (1986).

[2] Japan Chemical Fibers Association, Chemical Fibers, 42 (2014).

[3] S. Hiramatsu, Jpn. Res. Assn. Text. End-Uses. 32, 6, 88 (1991).

Fig. 1. Charged potential after 2 minutes

friction with polyester.

In-plane distribution of electrical conductivity of carbon nanowalls perpendicular to substrate

measured by conductive atomic force microscopy

Atsushi Ozaki1, Hiroki Kondo1, Takayoshi Tsutsumi1, Makoto Sekine1, Masaru Hori1, Mineo Hiramatsu2

1Nagoya University, Nagoya, Japan

2Meijo University, Nagoya, Japan

Carbon nanomaterials have attracted much attentions for superior properties of such as electrical

conductivity, thermal conductivity, mechanical strength, chemical stability and so forth. Among them,

carbon nanowalls (CNWs) have wall-like structures of several stacks of graphene sheets, which are

vertically self-standing normal to a substrate surface [1,2]. Electrical conductions of CNWs bulk horizontal

to substrates and their control by impurity doping technique have been reported in the previous paper [3].

For actual applications such as several types of sensors batteries, further researches on electrical

characteristic of CNWs are necessary, especially electrical conduction of CNWs in vertical direction have

to be clarified. Local electrical conduction properties depending on local structural fluctuations in CNWs

have also to be investigated, but there is no report about this matter.

In this study, microscopic electrical characteristics of CNWs in the vertical direction have been

studied by local current measurements using a conductive atomic force microscope (C-AFM).

The CNWs were grown by a radical-injection plasma-enhanced chemical vapor deposition

(RI-PECVD) system. This system consists of two types of plasma sources: a surface-wave excitation

plasma (SWP) and a capacitively-coupled plasma (CCP). H2 (50 sccm) and CH4 (100 sccm) gases were

injected into the SWP and CCP regions, respectively. The powers of 400 W applied to the both SWP and

CCP regions. The 3-μm-high CNWs were grown on a Cr (100 nm) / SiO2 (1 μm) / Si substrate at 800ºC

for 29 min. Then, the CNWs were embedded within an insulating UV resin. By polishing, its top-surface

became flat and top-edges of walls were exposed on the polished surface. Since the UV resin was filled in

the wall-interspace, it was to prevent the CNWs from collapsing due to mechanical stress in the horizontal

direction during polishing. It also enabled the AFM measurements on the edges of CNWs, which

intrinsically have large height fluctuation. Local electrical characteristics of each walls were measured

between the Cr underlayer and the Pt-coated Si cantilever using the C-AFM.

When applied 20 mV bias, the current flowed from the metal tip to the bottom Cr layer. The currents

were detected at the CNWs regions, but no current was detected in the UV resin region. In addition, the

average conductivity value at the branching points of walls were 10 times larger than that at straight walls,

which are attributed to the local structural variation of CNWs. In summary, the electrical characteristics of

the vertical direction of CNWs were successfully measured using the conductive AFM. Information in

relation with electric transports of CNWs is very useful for realizing future nanographene devices.

References

[1] M. Hiramatsu and M. Hori, Carbon nanowalls, Springer, 2010.

[2] K. Kobayashi et al., J. Appl. Phys. 101, 094306, 2007.

[3] W. Takeuchi et al., Appl. Phys. Lett. 92, 213103 (2008).

Engineering surface chemistry of cesium lead halide nanocrystals via acid-base reaction for stable, near-unity

photoluminescence quantum yield

Yunhee Cho1,2 and Hyoyoung Lee1,2,3,4 * 1Center for Integrated Nanostructure Physics (CINAP), Institute for Basic Science (IBS), Sungkyunkwan



Emails: [email protected], *[email protected]

Recently, halide-perovskite materials are promising for various applications including optoelectronic devices such as solar cells, photodetectors and phototransistors due to their high absorption density, carrier diffusion length and easy solution process.[1, 2] Thus, lots of methods have been developed to change the composition and morphology of the perovskite nanocrystals to modulate the optophysical properties. Especially, conduction band minimum mainly consists of molecular orbital of lead, while the valence band maximum of mixing of lead and halide molecular orbitals which form the metal halide octahedra as main crystalline structure of perovskite. Thus, the composition and structure of octahedra such as orientation and connectivity along the lattice are important to control the opto-electronic structure of cesium lead halide nanocrystals.[3, 4]

The surface structure of the nanocrystals is important for controlling the radiative relaxation process for near-unity photoluminescence quantum yield of the quantum dots. Thus, many previous papers tried to remove the surface defect states, control the position of energy level of the surface dangling bond or ligands which is out of the band gap. So, many previous reports exchange the ligand of the nanocrystals after synthesis without change of core structure in nanocrystals.[5] Compared to organic ligands with long alkyl chain, inorganic ligands is one of effective way to reduce the distance of the nanocrystals in film for increasing charge transfer and increase the device stability. And metal halide ligands is interesting ligands to modify the perovskite quantum dots which heal the halide vacancy of the surface, and modulate the metal cation in surface structure of the nanocrystals.[6, 7] However, still it is lack of study about the effects of insertion of metal cation into surface structure of perovskite nanocrystals.

Here in, surface structure of CsPbBr3 nanocrystals is treated with various metal halide which has different acidities. Thus, all of the nanocrystals treated with metal halide as inorganic ligands show increased stability while the photoluminescence quantum yield is much dependent on the acidity of the isovalent metal cation of the ligand. The optical and electrical properties of theses nanocomposite are analyzed using HRTEM, XRD, UV-vis absorption and PL spectroscopy.

[1] J. Shamsi, et al. Chemical Reviews 2019, 119, 3296-3348. [2] C. Katan, et al. Chemical Reviews 2019, 119, 3140-3192. [3] M. R. Filip, et al. Nature Communications 2014, 5, 5757. [4] B. Saparov, et al. Chemical Reviews 2016, 116, 4558-4596. [5] M. A. Boles, et al. Nature Materials 2016, 15, 141-153. [6] G. H. Ahmed, et al. ACS Energy Letters 2018, 3, 2301-2307. [7] N. Mondal, et al. ACS Energy Letters 2019, 4, 32-39.

Design of high efficiency photovoltaic modules by analysis of

a cell-to-module loss and gain mechanisms

Jisu Park, Wonje Oh, Jaehyeong Lee*

Department of Electrical and Computer Engineering, Sungkyunkwan University


Conventional PV modules are fabricated by interconnecting solar cells with a metal ribbon [1]. However, space is required for the electrical separation between the connecting cells, which results in an output power loss due to empty space in the module that cannot generate current. It also includes a busbar, a printed electrode on the front of the cell, which hides the active area that generates the current, causing output power loss.

On the other hand, shingled PV modules divide the full cell and apply electrically conductive adhesives (ECA) to the front busbars of the cell strips to bond them to the rear Ag pads of the other cell strips, thereby eliminating busbars at the front of the cells [2]. This reduces optical losses due to busbars and, unlike conventional PV modules, eliminates the space for cell separation, allowing the use of many cells in the same area, resulting in relatively high output power [3].

In this paper, in order to reduce cell-to-module (CTM) loss, the cell is connected by ECA, not by metal ribbon. We have compared the characteristics of the two modules by fabricating the conventional PV module and shingled PV module and presented the possibility of reducing CTM loss through shingled PV module. In addition, by simulating the properties of the shingled PV modules, we have identified CTM values that can be improved. we propose a method to reduce CTM loss by fabricating PV module by using Shingles technology, and compare CTM loss by fabricating conventional PV module and shingled PV module. As a result, the conventional PV module showed a CTM loss of -5.94% while the shingled PV module showed a CTM gain of 0.1%. In addition, the simulation results of the shingled PV module show that if the resistance of the ECA is lowered and the voltage drop problem is improved, a CTM gain of more than 1.23% can be achieved.

[1] A. El Amrani et al, Int. J. Photoenergy, 5 (2007)

[2] L. Theunissen et al, AIP Conf. Proc., 1999, 0800031 (2018)

[3] G. Beaucarne et al, Energy Proc., 67, 185 (2015)

Fig. 1 CTM loss analysis of shingled PV modules

Design of solar cell electrode for high power and cost savings of shingled photovoltaic module

WonJe Oh, JiSu Park, Jaehyeong Lee*

Department of Electrical and Computer Engineering, Sungkyunkwan University


Shingled module is able to manufacture high output module by applying dividing and bonding technology to solar cell. The cell dividing-bonding type module is capable of producing a high output module compared with a general module. However, because additional processes and materials are needed for splitting-bonding, the cost of production also increases. Therefore, it is necessary to reduce the cost in order to increase the productivity of the high output module using the dividing and bonding technique. Therefore, the manufacturing cost of the shingled module can be reduced by applying the new divided electrode pattern.

In this paper, we propose a new electrode pattern suitable for shingled module. The front electrode of the conventional solar cell consists of a bus bar and a finger. The finger moves the current produced in the active area. And The current produced by the multiple fingers is collected in the bus bar. Finally, the bus bar is in contact with the metal ribbon to allow current to flow. In the case of the backside as well, the Ag pad comes into contact with the metal ribbon and current flows. However, the shingling module connects the divided solar cells with a conductive adhesive. Therefore, new electrode patterns can be applied to reduce the amount of Ag paste used. Our new electrode pattern can reduce the cost of solar cells by reducing the use of silver paste. First, we designed an electrode pattern of a solar cell (156.75 mm x 156.75 mm), and the solar cell of this pattern can be applied to a Shingle PV module. This pattern is designed to reduce the amount of Ag paste used for electrode formation. We verified this electrode pattern using the Griddler2.5 simulation program. Also, conventional electrode patterns to be compared and analyzed with this pattern were also simulated. The simulation parameters are 2.25 mΩ / sq sheet resistance, 0.265 mΩ / sq front finger and silicon contact resistance, and 85 mΩ / sq emitter sheet resistance. Solar cells were also separated using laser equipment. The wavelength of the laser is 532 nm, the scan speed is 1300 mm / s, and the frequency is 50 kHz. We analyzed the characteristics before and after the dividing. When bonding solar cells, we used ECA (Electro-conductive Adhesive) to bond. We confirmed the characteristics before and after bonding. We have prepared two cell strips with different electrode patterns. The two cell strips are then bonded using the shingling system equipment. As a bonding method, an electrically conductive adhesive (ECA) was applied to the front bus bar of the split cell and the split cell was placed thereon. Finally, several cell strips are connected in series to form shiny cells.

We have proposed electrode pattern suitable for shingled solar cell which can reduce the amount of Ag paste. To demonstrate the effectiveness of this electrode pattern, we compared it with a solar cell with a common shingle electrode pattern. As a result of comparing the two types of shingled solar cells, they showed the same characteristics irrespective of bus bars. Therefore, the Shingle electrode pattern can reduce the amount of Ag paste by removing the bus bar. The result is that, in the case of a shingled solar cell, ECA used for bonding can act as a bus bar even if there is no bus bar on the cell strips. It is essential to reduce the cost of the splicing junction technology, and we have studied electrode patterns that can be applied to this technology. REFERENCES. [1] Nico Wöhrle et al, European Photovoltaic Solar Energy Conference and Exhibition, (2017).

[2] S. Braun et al, Energy procedia, 27, 227 (2012)

[3] J. Zhao et al, IEEE Electron Device Letters, 18, 48 (1997)

Fig. 1 Shingled cell bonded with cell strips with bus bar

Fig. 2 Shingled cell bonded with cell strips without bus bar

Table. 1 Comparison of Characteristics of two Shingled Cells

Synthesis of Complex Nanostructure using Galvanic Replacement

and Kirkendall Effect

Sungwoo Lee1, and Sungho Park1*

1 Department of Chemistry, Sungkyunkwan University, Suwon, Kyunggi-do 440-746, South Korea

Controlling the element and morphology of metallic nanoparticles enables us to tune

the optical, magnetic, and catalytic properties of nanoparticles. In this respect, hollow

nanostructures have gained enormous attention because of their large surface-to-volume ratio,

enhanced mass and charge transport efficiency, and high loading capacity. To synthesize hollow

nanoparticles, several approaches were used: (1) utilization of hard templates, (2) employment

of soft templates, (3) Galvanic replacement between less inert sacrificial templates and more

noble metal precursors, and (4) using Kirkendall effect.

Herein, we demonstrate complex nanostructures utilizing Pt nanorings as a core, a

subsequent growth of Ag around the Pt nanorings core, and using galvanic replacement reaction

and Kirkendall effect (by controlling reducing power of Au ions) between the Ag and the Au

ions for the Au nanoweb and the AgAu hollow nanoring structure at room temperature. The

uniform Pt nanoframe seed enables us to investigate optical property of PtAu nanoframe-core

shell nanorings via UV-visible-nearIR spectroscopy. Homogeneous synthesis of PtAu

Nanoframe-Core Ag@Au Shell Nanorings enables us to utilize them for plasmonic biosensor.

The surface of PtAu Nanoframe-Core Ag@Au Shell Nanorings were modified with antibody

against HA1 influenza antigens, and the variation in the magnitude of the in-plane dipole mode

was monitored as a function of concentration of HA1 antigens.

The enhanced control and analysis of complex nanostructures will enable us to design

new nanostructures and make an impact to nanostructure related applications such as sensor,

energy, and therapy.

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