Trap state passivation and photoactivation in wide band gap inorganic perovskite semiconductors

CsPbCl3 is a promising material to construct future short wavelength optoelectronic devices based on inorganic perovskite semiconductors. In this study, CsPbCl3 microcrystals were synthesized by a solution phase process. It was found that the photoluminescence (PL) intensities of the CsPbCl3 microcrystals can increase by up to five times under persistent irradiation of UV light without peak shifting, accompanied with an increased absorption coefficient above the band gap and decreased PL lifetime. This PL enhancement is a reversible process with excitation light switching on and off. The photoactivation process of the CsPbCl3 microcrystals is attributed to the passivation of the trap states.