1 Academic year 2016/2017

Republic of Tunisia University of Sousse

Higher Institute of Applied Sciences and Technology

Organic photovoltaic cells : OPV

Elaborated by : TALBI Malek El –AGUECH Mohamed Amin JEDIDI Sahar

Supervised by: Pr. DRIDI Cherif

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Outline

Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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Introduction

• 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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Motivation

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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Outline

Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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Definition

•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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Definition • Processes occurring in an organic

solar cell:

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Definition

Organic photovoltaic solar

cells

Single layer organic cells 

Bilayer organic cells

Bulk heterojunction organic cells

Electrode 1 (ITO)

Semiconducting polymer

Electrode 2 (Al,Mg,Ca) Electron

acceptorElectron donor PEDOTElectrode 1

(ITO) Electrode 1 (ITO)

Electrode 2 (Al,Mg,Ca)

Electrode 2 (Al,Mg,Ca)

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Outline

Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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How does it works ?

• Single layer organic cells :

Substrate

Semiconducting polymerElectrode 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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How does it works ?

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

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

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How does it works ?• Bi-layer organic cells :

In a bilayer OPV cell we have more layers:

Donor layer Acceptor layer Buffer 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.

How does it works ?

Bi-layer cells splits excitons give are much more efficiently

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• Bulk heterojunction organic cells :In a Bulk heterojunction organic cells we find

How does it works ?

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

How does it works ?

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Outline

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 recombination process 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 excitons is 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.

.

Disadvantages :

Structural formula of phenyl-C61-butyric acid methyl ester

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Advantages and limitsOrganic 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 limitsOrganic 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 cells VS Inorganic pv cells

Organic pv Inorganic pvLifetime 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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Outline

Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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ApplicationsPersonal mobile phone charger.

BIV(building integrated photovoltaics).

Clothes with embedded cells

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Outline

Introduction

How it works

Advantages and limits

Conclusion

Definition

Applications

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Conclusion

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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Perspectives

The organic solar energy research is developing:Replace fullerenes in bulk heterojunction with liquid crystal 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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References

[1] Askari Mohammad Bagher. Comparison of Organic Solar Cells and Inorganic Solar Cells. 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 & Electrical Characterization . September 16, 2011

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

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Thank you for your attention !