1Academic year 2016/2017

Republic of TunisiaUniversity of Sousse

Higher Institute of Applied Sciences and Technology

Organic photovoltaic cells : OPV

Elaborated by : TALBI MalekEl –AGUECH Mohamed AminJEDIDI Sahar

Supervised by: Pr. DRIDI Cherif

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Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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• The Earth receives 174,000 (TW) of incoming solar radiation at the upper atmosphere, so as a solution the sun became an important source of renewable energy .

Classic solar panel

•Through the ages mankind needed more and more energy.

• Oil, gas and coal will not last forever and it takes a number of years until new fossil fuels are formed.

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Organic photovoltaic (OPV) solar cells aim to provide an Earth-abundant and low-energy-production photovoltaic (PV) solution.

Why Organic solar cells ?

This New technology also has the theoretical potential to provide electricity at a lower cost than the classical solar cells ( inorganic pv cells)

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Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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•An organic solar cell device or organic photovoltaic cell (OPVC) is a class of solar cell that uses conductive organic polymers or small organic molecules for light absorption and charge transport.

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• Processes occurring in an organic solar cell:

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Organic photovoltaicsolar cells

Single layer organic cells

Bilayer organic cells

Bulk heterojunctionorganic cells

Electrode 1 (ITO)

Semiconductingpolymer

Electrode 2 (Al,Mg,Ca)

Electron acceptor

Electron donor PEDOT

Electrode 1 (ITO)Electrode 1 (ITO)

Electrode 2 (Al,Mg,Ca) Electrode 2 (Al,Mg,Ca)

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Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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• Single layer organic cells :

Substrate

Semiconductingpolymer

Electrode 1 (ITO)

Electrode 2 (Al,Mg,Ca)

Once an external circuit is made by connecting the two electrodes with a conductor, the difference in the work functions creates an electric field in the organic layer

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Electrons are excited to the LUMO leaving hole in the HOMO Excitons

Electric field in the organic layer :-Break up the excitonspairs.-Pulling electrons to the positive electrode.-Pulling holes to the negative electrode

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• Bi-layer organic cells :

In a bilayer OPV cell we have more layers:

Donor layer

Acceptor layer

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The layer with higher electron affinity and ionization potential is the electron acceptor, and the other layer is the electron donor.

Bi-layer cells splits excitons give are much more efficiently

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• Bulk heterojunction organic cells :

In a Bulk heterojunctionorganic cells we find

2 transparent electrods

1 active layer

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In charge transfer, both donors contribute directly to the generation of free charge carriers. Holes pass through only one donor domain before collection at the anode. In energy transfer, only one donor contributes to the production of holes. The second donor acts solely to absorb light, transferring extra energy to the first donor material. In parallel linkage, both donors produce excitons independently, which then migrate to their respective donor/acceptor interfaces and dissociate

ow

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Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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Advantages and limits

Single layer organic cells

Simple fabrication Low quantum efficiency and coversion efficiency: Exciton pairs not effectivly separated.

Advantages : Disadvantages :

The elctron-hole recombinationprocess is high: electrons and holes travel in the same material

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Advantages and limits

Bi-layer organic cells

Small interface that allows only excitons of a thin layer to reach it and get dissociated.

Disadvantages :

The diffusion length of excitonsis on the order of 4-10 nm.

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Advantages and limits

Bulk heterojunction organic cells

Fullerenes (PCBM ) : -Absorb very weakly visible light.- Poor electronic tunability.

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Disadvantages :

Replace these fullerenes with organic molecules

Structural formula of phenyl-C61-butyric acid methyl ester

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Advantages and limits

Organic photovoltaic cells:

Advantages:

Flexibility : roll to roll production

Low cost and light weight

Ease of integration

Ecological and economic benefits

Semitramsparent

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Advantages and limits

Organic photovoltaic cells:

Disadvantages:

Low efficiency: only 5% efficiency compared to the 15% of silicon cells

Low liftime < 10 000h

Low yield

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Advantages and limits

Organic pv Inorganic pv

Lifetime 10 000 h 10 years

Yield 5% to 11 % 11% 15% 25%

Cost Low hight

Transparency Transparent Opaque

Integration Easy Not easy

Flexibility Flexibl Not flexible

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Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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Applications

Personal mobile phone charger.

BIV(building integrated photovoltaics).

Clothes with embedded cells

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Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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Organic photovoltaic energy have the potential to be part of the world’s solution to the future of energy.

New generation of microelectronics : electronics everywhere

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The organic solar energy research is developing:

Reaserchers investigated the possibility to use liquid crystal semiconductor molecules in order to get bulk-ordered separated structures of p and n to obtain a better bulk architecture.

The key to future improvements in this field lies in better understanding the materials involved and their structures.

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[1] Askari Mohammad Bagher. Comparison of Organic Solar Cells and Inorganic SolarCells. International Journal of Renewable and Sustainable Energy. Vol. 3, No. 3, 2014, pp. 53-58. doi: 10.11648/j.ijrse.20140303.12

[2] Pulfrey, L.D. (1978). Photovoltaic Power Generation. New York: Van Nostrand Reinhold Co.

[3] M.G. Zebaze Kana. Introduction to Organic Solar Cell Devices & ElectricalCharacterization . September 16, 2011

[4] Krebs et. al., Solar Energy Materials and Solar Cells 2009

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Thank you for yourattention !