Khadije Khalili 1, Hossein Movla 2, Hamed Azari Najafabadi 1 1 Research Institute for Applied Physics and Astronomy (RIAPA), University of Tabriz, Tabriz, Iran 2 Department of Solid State Physics, Faculty of Physics, University of Tabriz, Tabriz, Iran RIAPA

☼ A short history of solar cells ☼ Polymer Solar Cell ☺ Principle and device configuration ☼ Organic Solar Cell Materials ☼ The objectives of our work ☺ Electric characteristics ☺ Results ☼ References 9/15/2011NSSC902 Contents

9/15/2011NSSC903 A short history of solar cells  First Generation - Single crystal silicon wafers (c-Si)  Second Generation - Amorphous silicon (a-Si) - Polycrystalline silicon (poly-Si) - Cadmium telluride (CdTe) - Copper indium gallium diselenide (CIGS) alloy  Third Generation - Nanocrystal solar cells - Photoelectrochemical (PEC) cells Gräetzel cells - Polymer solar cells - Dye sensitized solar cell (DSSC)  Fourth Generation - Hybrid - inorganic crystals within a polymer matrix

9/15/2011NSSC904 Polymer Solar Cell Principle and device configuration:  A Absorption of light  E Exciton dissociation  D Double-layer device  B Bulk-heterojunction (BHJ)  Charge transportation  Li Gui, LU GuangHao, et al. Progress in polymer solar cell, Chinese Science Bulletin (2007)

9/15/2011NSSC905 Organic Solar Cell Materials Most important Semiconducting polymers as 1- electron donor polymers: (MEH-PPV), (MDMOPPV), poly(3-hexeylthiophene) (P3HT), (PFO- DBT), (PCDTBT), regioregular poly(3-hexeylthiophene) (RR- P3HT) 2- hole acceptor materials: fullerene (C60) 6,6-phenyl C61 -butyric acid methyl ester (PC61BM), 6,6-phenyl C71-butyric acid methyl ester (PC71BM) and photovoltaic devices are fabricated on cleaned glass substrates with a patterned ITO layer. Other common materials are consist of the conducting polymer poly-wethylene dioxy thiophenex:poly-wstyrene sulfonatex (PEDOT:PSS), the active layer (P3HT:PCBM), and aluminum electrodes are thermally evaporated.

9/15/2011NSSC906 The objectives of our work are:  A. B. Walker, S. J. Martin, A. Kambili, J.Phys.: Condense. Matter 14, 9825(2002)

9/15/2011NSSC907 Electric characteristics:

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9/15/2011NSSC909 Fig 1. Variation in the band edge of the semiconductor in terms of the active region distance in thermal equilibrium for different donor like (n-type) dopings. 100 nm 200 nm

9/15/2011NSSC9010 Fig 2. Variation of electron mobility versus cell voltage.

9/15/2011NSSC9011 Fig 3. The injected electron profile in a semiconductor with cathode on the right hand side and anode on the left hand side. In the case of V=0 is thermal equilibrium. 100 nm 200 nm

9/15/2011NSSC9012 Fig 4. Diffusion and drift currents at 300 K in the double Schottky barrier device at 0.5 V. Diffusion current is larger than the drift current and the two currents flow in the opposite directions. 100 nm 200 nm

9/15/2011NSSC9013 Fig 5. Calculated l J-V characteristics of an ITO/PEDOT:PSS/P3HT:PCBM/Al solar cell in dark and under different illumination intensities. 100 nm 200 nm 40 mw/cm 2 60 mw/cm 2 80 mw/cm 2 40 mw/cm 2 60 mw/cm 2 80 mw/cm 2

9/15/2011NSSC9014 Fig 7. Calculated J-V characteristics of an ITO/PEDOT:PSS/P3HT:PCBM/Al solar cell in dark and under different illumination intensities. The dashed blue line is the Lampert et.al. calculated dark current. 40 mw/cm 2 60 mw/cm 2 80 mw/cm 2

9/15/2011NSSC9015 Fig 8. Calculated J-V characteristics of an ITO/PEDOT:PSS/P3HT:PCBM/Al solar cell for different thickness.

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9/15/2011NSSC9017 [12] W. U. Huynh, J. J. Dittmer, W. C. Libby, G. L. Whiting, A. P. Alivisatos, Adv.Funct.Mater. 13 (2003) 73 [13] J.Y.Kim, K.Lee, N.E.Coates, D.Moses, T.Nguyen,M.Dante,A.J.Heeger, Efficient tandem polymer solar cells fabricated by all-solution processing, Science 317(2007) 222. [14] C. J. Brabec, N. S. Sariciftci, J. C. Hummelen, Adv. Func. Mater. 11 (2001) 15. [15] H. Hoppe, N. Arnold, D. Meisner and N. S. Saricirtci: Modeling the optical absorption whit in conjugated polymer/fullerene-based bulk heterojunction organic solar cells, Sol. Energy Mater. Sol. Cells. 80, 105 (2003) [16] P. Kumar, S. C. Jain, V. Kumar, S. Chand, R. P. Tandon, J. Appl. Phys. 105, (2009). [17] A. B. Walker, S. J. Martin, and A. Kambili, J. Phys.: Condens. Matter 14, 9825 (2002). [18] S. J. Martin, Alison B. Walker, A. J. Campbell and D. D. C. Bradley, J. Appl. Phys. 98, (2005). [19] V. D. Mihailetchi, P. W. M. Blom, J. C. Hummelen, and M. T. Rispens, J. Appl. Phys. 94, 6849 (2003).

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