Boosting indoor perovskite photovoltaic performance via integrated compositional tuning, solvent engineering, and interfacial passivation

Passivation of surface defects at the interface between perovskite absorber layers and charge transport layers is important for reducing ion migration and nonradiative recombination, thereby improving the performance of perovskite photovoltaics. In indoor photovoltaics, the bandgap of the perovskite absorber layer must be engineered to optimize device performance, typically through compositional tuning of the precursor materials. Passivation becomes even more relevant when light intensity levels are low, as fewer charge carriers are generated and recombination can be much more detrimental. Herein, we simultaneously apply composition and anti-solvent engineering, varying bromine content in the perovskite and using chlorobenzene or dichlorobenzene, with phenethylammonium salts as interfacial passivators to (i) increase the crystallinity and grain sizes of the perovskite absorber layer, (ii) form a quasi-2D/3D perovskite heterojunction to passivate surface defects, and (iii) demonstrate light-intensity-dependent stability behavior. The optimized perovskite indoor photovoltaic devices with an aperture area of 0.093 cm2, using dichlorobenzene as the anti-solvent and phenethylammonium bromide as the passivation salt, achieved an improved efficiency of 36.2% with a power output of 112.2 μW cm−2, a fill factor of 76.5%, an open-circuit voltage of 1.04 V, and a short-circuit current density of 141.28 μA cm−2 under 1000 lux.