Bipolar Pseudohalide Ammonium Salts Bridged Perovskite Buried Interface toward Efficient Indoor Photovoltaics

Abstract Due to the higher photon energy under indoor photovoltaic conditions, using perovskite materials with wider bandgaps has become a consensus. However, updating perovskite absorbers requires additional adaptations involving at least two layers of transport materials and two interfaces, increasing the development complexity. This study acknowledges that the buried interface is the primary location for the generation of photoinduced carriers, and achieving efficient carrier separation and transport at this interface will solve most of the open circuit voltage ( V OC ) loss issues encountered in transitioning from solar photovoltaics to indoor photovoltaics. Therefore, a class of bipolar pseudohalide ammonium salts is proposed for use as bridging agents for the buried interface to effectively resolve the issues of lattice misalignment and insufficient carrier driving force at the buried interface when broadening the perovskite bandgap, thereby reducing V OC loss in indoor photovoltaics. The optimized device exhibits an excellent photoelectric conversion efficiency (PCE) of 41.04%, with a record‐high V OC of 1.08 V. It also demonstrates impressive long‐term operational stability with a T 80 lifetime of 1000 h. Substituting various non‐buried interface transport materials and different categories of wide‐bandgap perovskite absorbers does not alter the effectiveness, proving its universality.