Improved performance of perovskite solar cells with a TiO2/MoO3 core/shell nanoparticles doped PEDOT : PSS hole-transporter

We demonstrate improved performance of inverted planar heterojunction CH₃NH₃PbI_3-xCl_x perovskite solar cells with a TiO₂/MoO₃ core/shell nanoparticles (NPs) doped poly(3,4-ethylene dioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) hole-transporting layer (HTL). TiO₂/MoO₃ Core/shell NPs with size of approximately 40 nm are successfully prepared with a simple wet solution method and are interspersed into PEDOT: PSS layer to construct the HTL. The optimized device shows a high power conversion efficiency of 13.63%, which is dramatically improved compared with the reference device with a pristine PEDOT:PSS HTL. The improvement is mainly attributed to the increased crystalline of the CH₃NH₃PbI_3-xCl_x film with large-scale domains and a compact morphology. More interesting, the cells exhibit superior stability in ambient conditions, which is attributed to the inhibited penetration of moisture due to the compact morphology of the CH₃NH₃PbI_3-xCl_x film and the reduced hygroscopicity of the PEDOT:PSS film.