Simultaneous interfacial and bulk defect passivation and interface energy band alignment optimization via In(SCN2H4)3Cl3 diffusion doping for inverted perovskite solar cells

To address the interfacial and bulk defects and mismatched energy band alignment at perovskite/hole transport layr (HTL) interface in inverted perovskite solar cells (PSCs), here a novel In(SCN2H4)3Cl3 complex diffusion doping strategy was proposed to construct CH3NH3PbI3:In(SCN2H4)3Cl3 composite layer for poly[bis(4-phenyl) (2,4,6-trimethylphenyl)amine (PTAA)-based inverted PSCs. The In(tu)3Cl3 effectively promotes the quality of perovskite films with larger perovskite crystal grains and flatter and denser surfaces. Both theoretical and experimental results reveal that the In(SCN2H4)3Cl3 can not only passivate interfacial and bulk defects in perovskite layer, but also form a spatial separation of photogenerated charges through CH3NH3PbI3:In (SCN2H4)3Cl3 heterojunction interface, which effectively decreases the charge recombination and enhances charge separation and transport property in PSCs. Moreover, the In(SCN2H4)3Cl3 optimizes energy band align-ment at perovskite/PTAA interface and creates a polarization electric field at the PTAA/In(SCN2H4)3Cl3 interface directing toward PTAA layer, which promotes the hole transfer from the CH3NH3PbI3 to the PTAA and increases the open-circuit voltage (Voc). As a consequence, optimized inverted PSCs with CH3NH3PbI3:In(SCN2H4)3Cl3 layer achieve high efficiency of 21.25 % and also show a significantly improved long-term stability under different aging test conditions. Our work provides a valuable guide for designing efficient and stable inverted PSCs.