Ambient blade-coated perovskite solar cells with high reverse bias stability enabled by polymeric hole transporter design

Reverse bias stability remains a critical challenge for inverted perovskite solar cells (PSCs). While self-assembled monolayers (SAMs) boost efficiency, their low breakdown voltages limit device reliability. Thick PTAA layer improves breakdown voltage but suffers from poor wettability and efficiency loss, with unclear effects on device reverse bias stability. Here, we use electroluminescence mapping to reveal the critical role of hole transport layer (HTL) uniformity in affecting device reverse bias stability, and poor uniformity of current HTLs causes spatial heterogeneity that is not able to block electron injection and leads to device breakdown under reverse bias. Based on our study, we develop a polymeric Poly-PhPACz HTL with high conductivity and good wettability, achieving a breakdown voltage comparable to PTAA while maintaining high efficiencies across varying thicknesses. Ambient blade-coated Poly-PhPACz PSCs achieve 26.1% efficiency and retain 92% performance after 1,800 hours of light soaking. Further optimization yields a high breakdown voltage of -14.3 V without sacrificing efficiency, offering a promising pathway for stable PSCs.