Creation of a gradient polymer-fullerene interface in photovoltaic devices by thermally controlled interdiffusion

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Date
2002-12-01
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AIP Publishing
Abstract

Efficient polymer-fullerene photovoltaic devices require close proximity of the two materials to ensure photoexcited electron transfer from the semiconducting polymer to the fullerene acceptor. We describe studies in which a bilayer system consisting of spin-cast 2-methoxy-5-(2(')-ethylhexyloxy)-1,4-phenylenevinylene copolymer (MEH-PPV) and sublimed C-60 is heated above the MEH-PPV glass transition temperature in an inert environment, inducing an interdiffusion of the polymer and the fullerene layers. With this process, a controlled, bulk, gradient heterojunction is created bringing the fullerene molecules within the exciton diffusion radius of the MEH-PPV throughout the film to achieve highly efficient charge separation. The interdiffused devices show a dramatic decrease in photoluminescence and concomitant increase in short circuit currents, demonstrating the improved interface. (C) 2002 American Institute of Physics.

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Keywords
Photoinduced electron-transfer, Conducting-polymer, Blends, Cells
Citation
Drees, M; Premaratne, K; Graupner, W; et al., "Creation of a gradient polymer-fullerene interface in photovoltaic devices by thermally controlled interdiffusion," Appl. Phys. Lett. 81, 4607 (2002); http://dx.doi.org/10.1063/1.1522830