Inverted photovoltaic device based on ZnO and organic small molecule heterojunction

The solar cells with an inverted structure of indium tin oxide (ITO)/ZnO/copper-phthalocyanine (CuPc):fullerene (C60)/CuPc/poly(3,4-oxyethyleneoxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/Ag were fabricated. The current density–voltage curve indicates that ZnO was a highly effective electron-selective contact and plays important roles on the rectification behavior and the photovoltaic performance improvement. The incident photo to current conversion efficiency combined with the absorption spectrum indicates that most of the photocurrent generation was attributed to the excitation of CuPc. The shelf lifetime of unencapsulated devices was over 900 h in air due to the inverted structure which gives a promising way for fabrication of solar cells with improved stability.