Curriculum Vitae

1

Dr. Mrunal Sudhakar Mahajan

Contact Information: Address: D/o S. L. Mahajan,

Plot no. 12/63/C, Khote nagar,

Surkhasha Nagar, Jalgaon,

Maharashtra, 425001.

Mobile no.: 9975275485/7083060245

E-Mail: mrnlmhjn@gmail.com

Personal details:

• Date of birth: 30-12-1986

• Gender: Female

• Marital Status: Single

• Nationality: Indian

• Mother Tongue : Marathi

Educational Qualification:

1. S.S.C and H.S.C certificates :

Certificate

acquired

Board

Subjects

taken

Year of

Passing

% of

marks

S.S.C

CBSE Board

Science, Maths, Hindi,

English, Social

Science

2002 78.60

H.S.C

Maharashtra

State Board

Physics

/chemistry/

Biology/ mathematics

/English/Hindi

2004

63.50

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2. B.Sc and M.Sc degrees:

Degree

acquired

College/

University/

Institute

Subjects

taken

Year of

Passing

Marks

obtained

and % of

marks

Rank in

University/

Institute

B.Sc

Dr. A.G.D.

Bendale Mahila

Mahavidyalaya,

N.M.U

Physics

2007

1440/1900

75.00%

First Rank

Distinction

M.Sc School of

Physical Sciences

N.M.U

Physics

(Material

Sciences)

2009 1528/2000

76.00%

First Rank

in Institute

Distinction

Ph.D* School of Physical

Sciences.

North

Maharashtra

University

Physics

(Application

of new

material for

OSC’s)

2016

3. Details of Ph.D Work*:

• Ph.D Entrance Test (PET) : Qualified

• Date of Registration : 22.02.2011

• Subject: Physics ; Faculty: Science

• Topic of Research: “Some investigation on PEDOT: PSS thin films and

P3KHT: PCBM bulk heterojunction deposited by ultrasonic spray method for its

application in organic solar cells.”

• Name of Guide: Prof. Jaydeep V.Sali M.Sc, Ph.D

• Place of Research Work :Organic Photovoltaic Laboratory,

Department of Physics,

School of Physical Science,

North Maharashtra University, Jalgaon.

4. Other qualifications:

1. MSCIT Certificate (2008)

2. Certificate for Introductory course in German Language

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Research Expertise:

A. Thin film techniques:

Spin Coating, Ultrasonic Spray Coating, Thermal Evaporation System,

Chemical Bath Deposition, Chemical Vapor Deposition.

B. Characterization Techniques:

UV-Visible Spectroscopy, Photoluminescence Spectroscopy (Steady State as

well as Time Resolve spectroscopy), Raman Spectroscopy, Optical

Microscopy, Low angle X-Ray Diffraction, Atomic force Microscopy,

Scanning Electron Microscopy, Analysis of I-V Characteristics of solar cell

Conductivity measurements, Gas chromatography, Contact angle

measurements, Surface tension measurements for micro emulsion, Thickness

profilometer.

C. Research Interests :

a. Modeling and Simulation of single and dual feed Ultrasonic spray

technique for its application in fabricating various thin films from organic

and water solvents.

b. Use of Dual feed Ultrasonic Spray technique for Bulk heterojunction

formation of CNT: P3HT, P3HT: PCBM, P3KHT: PCBM active layers

and their optical spectroscopy studies (Absorption and PL spectra).

c. Organic solar cells, Device Fabrication using Ultrasonic Spray

Technique.

d. Bulk heterojunction active layer formation using Emulsion of orthogonal

solvents. Detail optical spectroscopy studies on Bulk heterojunction thin

films of water soluble P3KHT as an electron donor: organic solvent

soluble PCBM as an electron acceptor.

e. Investigation of the effect of electric field assisted thermal annealing

treatment on directional change in conductivity and morphology of

PEDOT: PSS thin films prepared using Ultrasonic spray method.

f. Study of Micro emulsions for its application in Organic solar cells.

g. Nanoparticle synthesis.

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Seminar/Conferences/Workshops/Symposia attended /participated:

1. Participated in Avishkar, 2009, presented model, 2nd prizes at university level, and

further represented North Maharashtra University for state level Avishkar, 2009 at

Amravati.

2. Participation in UGC-SAP Sponsored National conference on “Materials & Devices

for Future technology” at School of Physical Sciences, N.M.U. Jalgaon on 7th March

2011.

3. Participated in 4th INSPIRE Internship Program/Science Conclave: A Congregation of

Noble Laureates and Eminent Scientists at IIIT-A Allahabad during November 26-

December 02, 2011.

4. Presented Poster entitled “A novel method for preparation of bulk- heterojunction

of P3KHT and PCBM for its application in organic solar Cells ’’ in Avishkar,

2011 at university level at N.M.U. Jalgaon

5. Attended workshop entitled “Project, Thesis, and Paper writing in Chemistry”

conducted by school of Chemical Science, N.M.U, Jalgaon, 9th March 2012.

6. Attended Workshop on, “Research Methodology”, Organized by North Maharashtra

University as part of Pre Ph.D course work Paper- 1, during 20 September 2012 to 24

September 2012.

7. Participation in one day workshop on “Grid Connected Solar Photovoltaic Systems:

Design and applications” MACCIA conducted at Department of Physics, North

Maharashtra University, Jalgaon, 15 March, 2013.

8. Participation in Avishkar 2014 for University level and State level held at North

Maharashtra University, Jalgaon Campus.

9. Attended UGC –SAP sponsored one day National Workshop on “Advances in

Materials Processing” on 08 March 2014 organised by Physical Science, North

Maharastra University, Jalgaon.

10. Participation in INUP Familiarization Workshop on Nanofabrication Technologies,

held at IIT Bombay, Mumbai during May 26-28, 2014.

Awards and Prizes:

1. First Rank holder merit certificate for Masters Degree from North Maharashtra

University.

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2. Fellowship awarded from Chief Minister Fund for the Meritorious Student, North

Maharashtra University, Jalgaon for both First (2007-2008) and second year (2008-

2009) of Masters Degree.

3. “Shri Gyanchand H. Raisoni doctoral Fellowship” at North Maharashtra University,

Jalgaon-425001, 15.06.2012- May 2013.

4. Junior Research Fellowship (JRF) under UGC-BSR Fellowship Scheme in

department of Physics, North Maharashtra University, -Jalgaon 425001, 16 May

2013-30 August 2016.

5. First Prize in poster presentation in Avishkar in 2014 in Pure science at North

Maharashtra University

Publications:

1] Mrunal S. Mahajan, D. M. Marathe, Sanjay S. Ghosh, Jaydeep V. Sali, “Changes

in in-plane electrical conductivity of PEDOT: PSS thin films due to electric field

induced dipolar reorientation”, RSC Advances, 5, 86393 –8640, 1(2015). Impact

Factor: 3.84, doi: 10.1 39/c5ra13610e

2] Mrunal S. Mahajan, Ganesh S. Lonkar, Sanjay S. Ghosh, Mahendra B. Patil,

Dipak S. Dalal and Jaydeep V. Sali, “Formation of P3KHT: PCBM bulk-

heterojunction using orthogonal solvents by ultrasonic spray method”, J. Phys. D:

Appl. Phys.,vol.48, 65105(2015). Impact Factor: 2.27, doi: 10.1088/0022-

3727/48/26/265105

3] Mrunal S. Mahajan, Sanjay S. Ghosh, and Jaydeep V. Sali, “Improvement in Out-

of-plane Conductivity of PEDOT: PSS thin films due to electric field treatment at

elevated temperature”. American Journal of Material Science & Technology, Vol. 4,

No. 1, pp. 47-57(2015), doi:10.7726/ajmst.2015.1004.

4] Lonakar G. S., Mahajan M. S., Ghosh S. S., Sali J.V.,“Modelling thin film

formation by ultrasonic spray method: A case of PEDOT: PSS thin films”, Organic

Electronics, Vol.13, pp.2575–2581, (2012). ImpactFactor:3.83,

doi.:10.1016/j.orgel.2012.07.013.

5] S. S. Ghosh, G. S. Lonkar, M. S. Mahajan, S. R. Jadkar, V. S. Waman, “Bulk-

heterojunction morphology control during spin coating: Modeling diffusion assisted

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phase separation”, Appl. Phys. Lett., Vol. 101, 173305 (2012). Impact Factor: 3.30,

doi: 10.1063/1.4761931.

6] S.S Ghosh, G. S. Lonkar, M. S. Mahajan, S.R. Jadkar, J.V Sali, “P3HT: PCBM/

TiOx Interface modification through annealing for improvement in organic solar cell

performance”, American Journal of Material Science and technology, 1, pp. 88-95

(2013), doi:10.7726/ajmst.2013.1010

7] Sanjay S. Ghosh, Mrunal S. Mahajan, Ganesh S. Lonkar, Jaydeep V. Sali, Sandesh

R. Jadkar, “Poly (3-hexylthiophene): TiO2 bulk-heterojunction hybrid solar cells”

Research and Application of Material, 1,(4), pp. 44-48 (2013), DOI:

10.12966/ram.07.03.2013.

8] Deepak M. Marathe, Hemant S. Tarkas, Mrunal S. Mahajan, Sanjay S.

Ghosh, Rajendra S. Khadayate, Jaydeep V. Sali, “Poly 3-Hexylthiophene: Single

wall carbon nanotube active layer by dual feed ultrasonic spray method for solar cell

application”, Journal of Nanoelectronics and Optoelectronics,Vol.11, No.1, pp.12-

17(2016). Impact Factor: 0.39. DOI: 0.1166/jno.2016.1891

9] Deepak M. Marathe, Hemant S. Tarkas, Mrunal S. Mahajan, G.S. Lonkar,

S.R.Tak, Jaydeep V. Sali, “Bulk heterojunction thin film formation by single and

dual feed ultrasonic spray method for application in organic solar cell”, Journal of

Semiconductors, Vol. 37, No.9,(2016). DOI:10.1088/1674-4926/37/9/093003.

10] Hemant S. Tarkas, Deepak M. Marathe, Mrunal S. Mahajan, Faisal Muntaser,

Mahendra B. Patil, Swapnil R.. Tak and Jaydeep V. Sali, “Synthesis of tin

monosulfide (SnS) nanoparticles using surfactant free microemulsion (SFME) with

the single microemulsion scheme”, Mater. Res. Express, Vol. 4, 025018, (2017)

Curriculum Vitae

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*Summary of Thesis work:

Increased demands for energy throughout the world have increased the seriousness

for the development of renewable source technologies such as Photovoltaic technologies.

In our Thesis, I have focused on following two issues:

1. Bulk heterojunction morphology in respect to purity of phases

In OSC, Bulk heterojunction structures (BHJ) have been regarded as efficient

architecture that is assumed to successfully fulfill morphological requirements of active

layer for achieving high efficiency. Control over the dimensions of two phases, purity of

phases, phase separations, and connectivity of phases etc in BHJ become difficult during

processing of thin film, due to present conventional method for preparation of BHJ in

which both the electron donor and electron acceptor are employed in same organic

solvent and are intermixed intimately with each other at molecular level in the solution.

2. Conductivity of Buffer Layer

PEDOT: PSS is the organic polymer, has been used as an interfacial layer to improve

the hole injection and reduces the chance of shorts creation in the organic devices by

smoothening the rough surface of Indium tin oxide electrodes and active layer. However,

its use as a transparent conducting electrode in flexible device that require higher

electrical conductivity is still restricted.

In my Thesis I worked out with these issues. Following is the brief summary of my work:

We present a novel concept of formation of Bulk heterojunction (BHJ) by Ultrasonic

spray method, wherein, the electron donor and electron acceptor are dissolved in

orthogonal solvents. We are able to form emulsion of solution using water and

chlorobenzene, which are orthogonal solvents. Still use of P3KHT with electron acceptor

such as PCBM in BHJ has been restricted due to either solubility of P3KHT in organic

solvent or rare possibility of solubility of PCBM in water. However, emulsion of solution

prepared using orthogonal solvent enables the use of combination of P3KHT: PCBM for

formation of BHJ.

In this thesis, Bulk heterojunction thin film have been achieved using Ultrasonic spray

method which is considered as a potential roll to roll compatible processing method for

fabrication of solution processable optoelectronics devices. Process parameters of

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fabrication process play very important role in achieving the required morphology of thin

films.

[A] Considering importance of optimization of process parameters, we modeled the

Ultrasonic spray process. The modeling suggest the possibility of formation of

interconnecting phases of two components in BHJ formed using orthogonal solvents if

proper process parameter are chosen. Proposed model is based on the result of extended

simulation, wherein, we consider the probability of droplets overlapping on the substrate

during the course of spray process.

(a) We obtained the picture of droplets overlapping at every millisecond of 1sec (say) of

ON spray time of intermittent shot. It could be seen from the simulation results that

during 1 second spray ON time, with 10ml/hr solution flow rate almost all the

deposition area is covered by the sprayed droplets forming single film layer. The film

formation process through, say 100 ON-OFF cycles of spray shot is, thus a layer-by-

layer deposition process.

(b) As the spray deposition progresses, within 1 sec spray shot, number of un-overlapped

drops decreases and drops with different degree of overlapping (sets of different

numbers of drops stacking one over other) form. At end of 1sec ON time of spray shot,

there is availability of drops with varying degree of overlapping on the substrate. From

simulation, we obtain percentage of total drops with different degree of overlapping as

a function of time, during the 1 second of spray shot.

(c) Dry time for the sprayed drop will be decided by their degree of overlapping, solvent

properties and substrate temperature. Drops with different degree of overlapping will

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have different mass, so will take different time for their complete evaporation. We

calculated the time taken by mass of drops with different degree of overlapping, at

different substrate temperature.

(d) It can be seen from the results of calculations that, at low substrate temperature, if the

spraying is continuous rather than intermittent, solution pooling may occur. The same

is true for even intermittent spray with low substrate temperature, which is

insufficient for solvent evaporation and short intermediate OFF spray time between

two spray shots. Use of higher substrate temperature for longer intermediate OFF

time, on the other hand, may results in dried layer by layer deposition of drops. In this

case, due to unavailability of wet drops of either solution to interconnect, the phases

form may not be interconnecting. It could be concluded that the availability of wet

drops at end of each spray sequences, that will depend on the drops drying time (as

decided by drops overlapping and substrate temperature) and the intermediate OFF

time available between spray shots, will decide the inter-layer connectivity between

phases after each ON –OFF spray sequence in the spray cycle. Thus, the choice of

proper substrate temperature and time required between intermittent spray i.e. ON –

OFF spray time, for given solution, spraying with certain flow rate will ensure the

interconnecting phases within the BHJ thin film.

[B] Emulsion of solution method:

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Following method represents the Emulsion of solution method:

(1)Preparation of P3KHT Solution: P3KHT solution was prepared using deionised water

and P3KHT polymer. (2) Preparation of PCBM Solution: PCBM solution was prepared

using chlorobenzene and PCBM. (3) Emulsion of solution: P3KHT Solution and PCBM

solution were then mixed and sonicated for intimate mixing using ultrasonic bath.

Significant PL quenching indicating efficient exciton separation before recombination is

observed for BHJ prepared by the emulsion of solution method. BHJ thin film prepared

from such solution using solution processable method such as spin coating, drop casting

and Ultrasonic spray method also show efficient PL quenching. It indicates that the

emulsion of solution as a precursor is applicable for any solution processable method

including ultrasonic spray method.

[B] The totally unmixed solvents in the source solution lead to BHJ with pure phase

domains with sharp interfaces. Complementary experiment and XRD analysis confirms

formation of sharp donor/acceptor interfaces with pure phase domains in the BHJ film

prepared using orthogonal solvent.

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33

400 500 600 700 8000.0

0.5

1.0

1.5

2.0

2.5

Abs

orba

nce

Wavelenght(nm)

550 600 650 700 750 800 850 9000.0

0.5

1.0

1.5

2.0

Nor

mal

ize

PL

Inte

nsity

Wavelength (nm)

P3KHT P3KHT/PCBM bilayer P3KHT after PCBM is

removed from bilayer

P3KHT P3KHT/PCBM bilayer P3KHT after PCBM is

removed from bilayer

(a) (b)

++

(a) optical absorption and (b) Steady state PL spectra of pristine P3KHT thin film

( ), thin film of P3KHT/PCBM bi-layer ( ) and P3KHT thin film from which

PCBM overlayer have been removed by dipping the bilayer in chlorobenzene

solvent ( ).

P3KHT

PCBM

Bilayer of P3KHT /PCBM on glass substrate

P3KHT

P3KHT after PCBM removed from bilayer

PCBM over layerremoved bydipping the bilayerin Chlorobenzenesolvent

[D] Comparative Study of BHJ Formed by three different approaches

Three different ways for P3KHT: PCBM BHJ formation using Ultrasonic spray technique has

been presented in the experimental work.

Method 1: Dual Feed method: The two solutions (P3KHT in water and PCBM in

chlorobenzene) were fed to two channels in the dual feed ultrasonic nozzle, independently

and sprayed simultaneously.

Method 2: Emulsion of solutions method: P3KHT solution in water and PCBM solution in

chlorobenzene were prepared. By choosing specific volume ratios of two solutions

(chlorobenzene: water as 1:40) a stable emulsion of these two non-mixing solutions was

obtained. This emulsion was used as a precursor for the donor and acceptor and was sprayed

using a single channel of the dual-feed ultrasonic spray nozzle.

Method 3: Solvent Assisted method: As shown in simulation studies, at around 35 oC, at the

end of the spray shot of 1 sec, the film can be in partially wet condition due to availability of

overlapped drops of chlorobenzene. Secondly, the volume proportion of chlorobenzene and

water solution was 1:40. With an aim to improve the possibility of interconnecting

chlorobenzene droplets, a flood spray of pristine chlorobenzene (through second channel of

spray nozzle) was introduced for 1 sec immediately after the 1 sec spray shot of emulsion

(through first channel of spray nozzle), followed by OFF time of 3 seconds.

For emulsion of solutions method, the optimum substrate temperature chosen was 35oC (Low

Temperature regime). For solvent assisted method the temperature had to be raised a little (37

oC) due to flood spray of chlorobenzene. For solvent assisted and dual feed method, we

prepared BHJ with minimum possible substrate temperature (Low-T regime) without solution

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pooling, as observed by necked eyes, during the deposition. We also prepared BHJ by these

three ways at higher substrate temperature ensuring complete droplets drying before next

spray-shot (High-T regime).

Changes in optical absorption and PL spectra upon short and extended annealing time

indicate that the BHJ formed using the orthogonal solvents lead to bilayer type structure,

formed by sprayed droplets of orthogonal solution, embedded with BHJ morphology.

The possibility of formation of pure phase domains and sharp interfaces in BHJ through a

proposed system may lead to application in organic optoelectronic device including

organic solar cells. Fabrication of OSC with application of BHJ active layer formed by the

emulsion of solution method demonstrates that the device prepared with BHJ formed by

the emulsion of solution method works.

2. Electric Field Treatment on PEDOT: PSS thin films:

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1. Electric field treatment parallel to the plane of PEDOT: PSS thin film

We have shown that the application of thermal annealing assisted electric field treatment on

PEDOT: PSS thin films lead to anisotropic behavior of electrical in-plane conductivity. Due

to intrinsically different morphology of PEDOT: PSS thin films prepared without (pristine

PEDOT: PSS) and with addition of DMSO (DMSO added PEDOT: PSS), resulting effect on

electrical in-plane conductivity was not similar. In pristine PEDOT: PSS thin films, electric

field treatment cause rise in electrical in-plane conductivity in orthogonal direction to electric

field and it falls in direction of electric field.. DMSO added thin films show initial isotropic

switching from high conductivity to low conductivity state. Prolonged electric field

treatment results in significant fall in in-plane electrical conductivity specifically in the

direction of electric field. A model, based on re-orientation of polymer chains caused by

interaction of electric field and electric dipoles of PEDOT: PSS chains, has been proposed to

explain this behavior. The hypothesis is supported by the results of Raman spectroscopy and

absorption spectra of these films.

2. Electric field treatment perpendicular to the plane of PEDOT: PSS thin film

We have shown that electric field treatment done perpendicular to the plane of PEDOT: PSS

thin films at elevated temperature results about an order of rise in out of plane conductivity of

PEDOT: PSS thin films. The effect is more pronounced in pristine PEDOT: PSS thin films

and is marginal for DMSO added PEDOT: PSS films. The results obtain from Raman spectra

and Absorption Spectra of treated PEDOT: PSS films indicate that changes in conductivity

are due to conformational changes in the polymer chains induced by the applied electric field

to these thin films at elevated temperature.

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Contact for References:

1] Prof. Jaydeep V. Sali

Address:Department of Physics,

School of Physical Science,

North Maharashtra University, Jalgaon

Maharashtra-425001

Telephone: 0257-2257474 (ext: 214), Mobile No. : 9403451667

Fax: 0257-2258403

Email: jvsali@nmu.ac.in

2] Dr. S. S. Ghosh

Address: Department of Physics,

School of Physical Science,

North Maharashtra University, Jalgaon

Maharashtra-425001

Telephone: 0257-2257474 (ext:214), Mobile No. :

Email: ssghosh@nmu.ac.in

Declaration:

I hereby declared that all the above information given by me is true to the best of my

knowledge.

Dr. Mrunal S. Mahajan