Virginia TechDrees, M.Premaratne, K.Graupner, W.Heflin, James R.Davis, Ruth M.Marciu, D.Miller, M.2014-04-162014-04-162002-12-01Drees, 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/10.1063/1.15228300003-6951http://hdl.handle.net/10919/47371Efficient 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.application/pdfenIn CopyrightPhotoinduced electron-transferConducting-polymerBlendsCellsArticle - Refereedhttp://scitation.aip.org/content/aip/journal/apl/81/24/10.1063/1.1522830https://doi.org/10.1063/1.1522830