Dependence of device performance on the thickness of compact TiO2 layer in perovskite/TiO2 planar heterojunction solar cells

Planar heterojunction perovskite solar cells (PHJ-PSCs) based on CH3NH3PbI3/TiO2 with high-quality CH3NH3PbI3 films were fabricated by two-step interdiffusion technology. The photovoltaic performance of PHJ-PSCs, including short-circuit-current (J(sc)) and open-circuit-voltage (V-oc), was found to be strongly dependent on the thickness of TiO2 layer. The largest J(sc) was obtained at an optimized TiO2 thickness of 65nm, resulting in a moderate power conversion efficiency (PCE) of 8.40% with a device structure of fluorine doped SnO2/compact TiO2/CH3NH3PbI3/Spiro-MeOTAD/Ag. A thicker compact TiO2 film could lead to a lower V-oc, and the physical mechanism between the V-oc and the thickness of compact TiO2 layer was disclosed. (C) 2015 AIP Publishing LLC.