Chemical Linkage and Passivation at Buried Interface for Thermally Stable Inverted Perovskite Solar Cells with Efficiency over 22%

Poly[bis(4-phenyl)-(2,4,6-trimethylphenyl)amine](PTAA)has been developed as one of the most popular hole transport layer(HTL)materials in inverted perovskite solar cells(PSCs).However,the efficiency,thermal stability,and reproducibility of PTAA-based devices are still largely limited by underoptimized chemical interaction,energy level alignment,and contact affinity at the PTAA/perovskite interface.To this end,we introduced a bilateral chemical linker to simultaneously achieve favorable chemical interaction with the PTAA underlayer and form robust coordination bonding with the buried perovskite bottom layer,which beneficially improved the contact affinity,facilitated the hole extraction,well-passivated the interfacial defects,and relieved the nonradiative charge recombination at the HTL/perovskite buried interface.The inverted PSCs modified with interfacial chemical linker exhibited consistently higher power conversion efficiencies and performance reproducibility than that of the PTAA-only devices.Combined with the blade-coated FA0.4MA0.6PbI3 perovskite layer,a champion efficiency of 22.23%has been achieved,which is one of the highest reported values for the inverted PSCs based on the bilayer HTL.The targeted device showed enhanced thermal stability under continuous heating at 85℃ owing to suppressed composition segregation with robust interfacial linkage and consolidation.This work offers a new insight towards making efficient,thermally stable,and reproducible perovskite photovoltaics.