Carbon-double-bond-free printed solar cells from TiO₂/CH₃NH₃PbI₃/CuSCN/Au: structural control and photoaging effects.

Carbon double bond-free printed solar cells have been fabricated with the structure <F-doped SnO2 (FTO)/dense TiO2/nanocrystalline TiO2/CH3NH3PbI3/Au> and <FTO/dense TiO2/nanocrystalline TiO2/CH3NH3PbI3/CuSCN/Au>, in which CuSCN acts as a hole conductor. The thickness of the CH3NH3PbI3 layer is controlled by a hot air flow during spin coating. The best conversion efficiency (4.86%) is obtained with <FTO/dense TiO2/nanocrystalline TiO2/thin CH3NH3PbI3 (hot-air dried)/CuSCN/Au>. However, a thick CH3NH3PbI3 layer on CuSCN is better for light-exposure stability (100 mW cm(-2) AM 1.5) when not encapsulated. Without the CuSCN coverage, the black CH3NH3PbI3 crystal changes to yellow during the light-exposure stability test, which is due to the transformation of the CH3NH3PbI3 perovskite crystal into hexagonal PbI2.