Efficient inorganic <scp>CsPbI₂Br</scp> perovskite indoor photovoltaics demonstrated via slower crystallization by incorporated dimethylammonium iodide

Abstract

Abstract Although inorganic CsPbI 2 Br perovskite has an ideal bandgap for indoor photovoltaics (IPVs), its poor solubility causes rapid crystallization during spin‐coating process and deteriorates the performance of IPVs. Here, efficient CsPbI 2 Br IPVs are demonstrated through slower crystallization by introduction of dimethylammonium iodide (DMAI), which has better solubility in perovskite solvent compared to the inorganic CsPbI 2 Br and is easily eliminated by thermal‐annealing. Consequently, the incorporation of DMAI results in the CsPbI 2 Br film with enlarged crystal grains with reduced interface traps. In addition, the incorporated DMAI orients preferentially the CsPbI 2 Br crystals to expose (110) facet. Through controlling the amount of incorporated DMAI, eventually the CsPbI 2 Br IPVs with 35.22% (0.096 cm 2 ), 35.08% (1 cm 2 ), and 29.80% (25 cm 2 ) of power conversion efficiency under illumination of 1000 lux light‐emitting diode lamp are achieved. The unencapsulated device has good long‐term stability under 1000 lux lamp for 1000 h. image