MATERIALS SCIENCE COLLOQUIUM

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ABSTRACT: Our objective in this presentation is two-fold. First, we provide a general overview of the optical and electronic processes that take place in a solid-state organic solar cell, which we define as a cell in which the semiconducting materials between the electrodes are organic, be them polymers, oligomers, or small molecules. We briefly turn our attention to: (i) optical absorption and exciton formation; (ii) exciton migration to the donor-acceptor interface; (iii) exciton dissociation into charge carriers, resulting in the appearance of holes in the donor and electrons in the acceptor; (iv) charge carrier mobility; and (v) charge collection at the electrodes,1-4 see Figure 1. Secondly, we underline the complexity of the processes taking place at the nanoscale at the organic/organic interface and highlight the balance that needs to be found for the optimization of materials parameters in terms of photovoltaic performance.

Figure 1. Simplified sketch of the electronic and optical processes taking place in an organic solar cell.

(1) B. Kippelen and J.L. Bredas , Energy & Environmental Science 2, 251 (2009).
(2) J.L. Bredas, J. Norton, J. Cornil, and V. Coropceanu, Acc. Chem. Res. 42, 1691 (2009).
(3) C. Risko, M.D. McGehee, and J.L. Bredas, Chemical Science, 2, 1200 (2011).
(4) D. Beljonne, J. Cornil, L. Muccioli, C. Zannoni, J.L. Bredas, and F. Castet, Chem. Mat. 23, 591 (2011).