Analysis on the defect states of FA_xMA_1−xPbI₃ perovskite single crystals grown by inverse-temperature crystallization

The FA_0.6MA_0.4PbI₃, FA_0.8MA_0.2PbI₃ and FAPbI₃ perovskite single crystals were prepared by the inverse temperature crystallization method. From the deep level transient spectroscopy (DLTS) measurement and optical conduction DLTS, the FA_0.6MA_0.4PbI₃ and FA_0.8MA_0.2PbI₃ samples had the majority carrier defects of E2 and E3 with E_a of 0.52 and 0.59 eV, which were positioned below the conduction band minimum, and the FAPbI₃ sample had the minority carrier defect of H2 with E_a of 0.60 eV above the valence band maximum. The origin of the defect states of E2, E3 and H2 are related to FA-I antisite defects, Pb interstitial defects and iodine vacancy, respectively. Among the samples, the defect density (N_t) of H2 on FAPbI₃ was lower than that of any other sample, although the normalized integrated photoluminescence intensity of the FA_0.8MA_0.2PbI₃ sample was higher than that of any other sample. This is due to the fact that H2 was a minority carrier defect and E2 and E3 were majority carrier defects.