Performance enhancement of inverted polymer solar cells with fullerene ester derivant-modified ZnO film as cathode buffer layer

In this paper, we reported that ZnO nanoparticles (NPs) film modified with C-60 pyrrolidine tris-acid ethyl ester (PyC60) was used as cathode buffer layer in inverted polymer solar cells. The resultant device with a blend of PTB7:PC71BM as photoactive materials exhibited an open-circuit voltage (V-OC) of 0.753 V, a short-circuit current (J(SC)) of 16.04 mA cm(-2), a fill factor (FF) of 72.5%, and an overall power conversion efficiency (PCE) of 8.76%. It was higher than the control devices based on sole ZnO NPs film or ZnO: PyC60 hybrid film as cathode buffer layer. It was found that the morphology improvement of ZnO/PyC60 film contributed to reducing series loss and interfacial charge recombination. In addition, it improved the interfacial contact with photoactive layer. The results increased electron injection and collection efficiency, and improved FF. (C) 2014 Elsevier B.V. All rights reserved.