Fabricating high performance conventional and inverted polymer solar cells by spray coating in air

Abstract

We report bulk heterojunction organic solar cells utilising the electron-donating polymer PffBT4T-2OD blended with the fullerene acceptor PC71BM, with cells explored based on both conventional and inverted architectures. As charge-transporting layers, we utilise the hole-transporting polymer poly (2, 3-dihydrothieno-1, 4-dioxin)-poly (styrenesulfonate) (PEDOT:PSS) in conventional device architectures, and zinc oxide (ZnO) electron-transport in inverted devices. Critically, all charge-transporting layers and the poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt- (3,3‴-di(2-octyldodecyl) 2,2’; 5′,2’’; 5″,2‴ -quaterthiophen-5,5‴-diyl)] (PffBT4T-2OD): [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) active layer blend were spray coated in air. We demonstrate champion devices having a power conversion efficiency of 8.13% and 8.43% for conventional and inverted architectures respectively.