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(SCN 2 H 4 ) 3 Cl 3 complex diffusion doping strategy was proposed to construct CH 3 NH 3 PbI 3 :In(SCN 2 H 4 ) 3 Cl 3 composite layer for poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA)-based inverted PSCs. The In(tu) 3 Cl 3 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(SCN 2 H 4 ) 3 Cl 3 can not only passivate interfacial and bulk defects in perovskite layer, but also form a spatial separation of photogenerated charges through CH 3 NH 3 PbI 3 :In(SCN 2 H 4 ) 3 Cl 3 heterojunction interface, which effectively decreases the charge recombination and enhances charge separation and transport property in PSCs. Moreover, the In(SCN 2 H 4 ) 3 Cl 3 optimizes energy band alignment at perovskite/PTAA interface and creates a polarization electric field at the PTAA/In(SCN 2 H 4 ) 3 Cl 3 interface directing toward PTAA layer, which promotes the hole transfer from the CH 3 NH 3 PbI 3 to the PTAA and increases the open-circuit voltage ( V oc ). As a consequence, optimized inverted PSCs with CH 3 NH 3 PbI 3 :In(SCN 2 H 4 ) 3 Cl 3 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.