The influence of strain on the properties of FAPbI3 photoactive phase

Abstract

Here the optoelectronic, defect, and mechanical properties for strain-induced α-FAPbI₃ are indicated. Strain range among -5% to 5% induces the bandgap varying in 0.98 eV to 1.91 eV, and strain along the [111] crystal orientation maintains direct bandgap, while the strain along the [100] and [110] orientations may turn the direct bandgap to indirect bandgap. Compressive strain transfers the iodine vacancy energy from the deep-level to shallow one, which stabilizes the photoactive via elevating the α-FAPbI3 phase. The [111] orientation under -2% strain achieving a photoelectric conversion efficiency (PCE) of 31.9%, providing optimized strategies for designing efficient and stable perovskite solar cells.