Tailoring Triple‐Anion Perovskite Material for Indoor Light Harvesting with Restrained Halide Segregation and Record High Efficiency Beyond 36%

Abstract Indoor photovoltaics are promising to enable self‐powered electronic devices for the Internet of Things. Here, reported is a triple‐anion CH 3 NH 3 PbI 2− x BrCl x perovskite film, of which the bandgap is specially designed for indoor light harvesting to achieve a record high efficiency of 36.2% with distinctive high open circuit voltage ( V oc ) of 1.028 V under standard 1000 lux fluorescent light. The involvement of both bromide and chloride suppresses the trap‐states and nonradiative recombination loss, exhibiting a remarkable ideality factor of 1.097. The introduction of chloride successfully restrains the halide segregation of iodide and bromide, stabilizing the triple‐anion perovskite film. The devices show an excellent long‐term performance, sustaining over 95% of original efficiency under continuous light soaking over 2000 h. These findings show the importance and potential of I/Br/Cl triple‐anion perovskite with tailored bandgap and suppressed trap‐states in stable and efficient indoor light recycling.