Organic solar cell charge recombination

Howard lA, Laquai F (2010) Optical probes of charge generation and recombination in bulk heterojunction organic solar cells. Macromol Chem Phys 211 2063... 

A further aspect, not yet treated in detail for organic solar cells, is the role of intermediate charge-transfer states, such as bound polaron pairs, in mediating charge separation and recombination rates (Morteani et al, 2004). 

Lemaur, V., Steel, M., Beljonne, D., Bredas, J.L., and Comil, J., Photoinduced charge generation and recombination dynamics in model donor/acceptor pairs for organic solar cell applications A full quantum-chemical treatment, J. Am. Chem. Soc., 127, 6077, 2005. 

The work on PCBMipolythiophene blends underlines that, in order to increase the efficiency of organic solar cells, the kinetics of the charge-transfer state are a key factor. To improve device efficiency the rate of charge-transfer state recombination should be reduced and the rate of separation of charges from the charge-transfer state should be increased. In order to modify these rates the mechanisms by which the processes occur must be understood in greater detail. 

Charge Generation and Recombination in Organic Solar Cells with High Open-Circuit Voltages... 

T. Kawatsu, V. Coropceanu, A.J. Ye, and J.L. Bredas, Quantum-chemical approach to electronic coupling Application to charge separation and charge recombination pathways in a model molecular donor-acceptor system for organic solar cells, J. Phys. Chem. C, 112, 3429-3433 (2008). 

Molecular electronic coupling controls charge recombination kinetics in organic solar cells of low bandgap diketopyrrolopyrrole, carbazole, and thiophene polymers. J. Phys. Chem. C 117, 8719-8726. 

Yi Y, Coropceanu V, Bredas J-L (2011) A comparative theoretical study of exciton-dissociation and charge-recombination processes in oligothiophene/fuUerene and oligothiophene/perylenediimide complexes for organic solar cells. J Mater Chem 21 1479... 

Abstract We review the methods used to simulate the optoelectronic response of organic solar cells and focus on the application of one-dimensional drift-diffusion simulations. We discuss how the important physical processes are treated and review some of the experiments necessary to determine the input parameters for device simulations. To illustrate the usefulness of drift-diffusion simulations, we discuss several case studies, addressing the influence of charged defects on transport in bipolar and unipolar devices, the influence of defects on recombination, device performance and ideality factors. To illustrate frequency domain simulations, we show how to determine the validity range of Mott-Schottky plots for thin devices. Finally, we discuss an example where optical simulations are used to calculate the parasitic absorption in contact layers. 

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