Efficient inorganic CsPbI2Br perovskite indoor photovoltaics demonstrated via slower crystallization by incorporated dimethylammonium iodide

Abstract

Abstract Although inorganic CsPbI2Br 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 CsPbI2Br IPVs are demonstrated through slower crystallization by introduction of dimethylammonium iodide (DMAI), which has better solubility in perovskite solvent compared to the inorganic CsPbI2Br and is easily eliminated by thermal‐annealing. Consequently, the incorporation of DMAI results in the CsPbI2Br film with enlarged crystal grains with reduced interface traps. In addition, the incorporated DMAI orients preferentially the CsPbI2Br crystals to expose (110) facet. Through controlling the amount of incorporated DMAI, eventually the CsPbI2Br IPVs with 35.22% (0.096 cm2), 35.08% (1 cm2), and 29.80% (25 cm2) 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.

Keywords

• crystallization control
• CsPbI2Br
• dimethylammonium iodide
• grain growth
• indoor photovoltaics
• solubility