Passivation of defective states in single crystal MAPbBr3 and their optoelectronic properties study

We fabricated high-quality Methylpropyl lead bromide (MAPbBr3) single crystals (SC) by introducing moderate amount electron-rich amino-terminated polyoxypropylene (PEA) additives via inverse temperature crystallization (ITC) method. The intramolecular vibrations and defective states of prepared MAPbBr3 single crystals were systemically studied by the in situ variable-temperature Fourier Transform Infrared (FTIR), X-ray photoelectron spectroscopy (XPS), the synchrotron-based X-ray absorption near edge structure (XANES) et al. We find the proper amount PEA additives would prevent the formation of intermediate states and crystal boundaries, passivating the density of defective states. The X-ray detection properties of single-crystal MAPbBr3 crystals were investigated, using both high dose and low dose X-ray photons at 40 keV in synchrotron beamlines. The photocurrent of optimized PEA-treated MAPbBr3 single crystals demonstrate better performance compared with the as-prepared single crystals. Meanwhile, the decay time of MAPbBr3 single crystal is decreased from 376 ns to 17.1 ns by Time-resolved photoluminescence (TRPL) decay measurement, owing to the defect passivation by 0.5 wt% PEA additives. The PEA-treated single crystals possess much faster decay time than the commercialized Cerium-doped Yttrium Aluminum Garnet (Ce:YAG) scintillator (∼100ns). These results help elucidate the passivation of defective states and contribute paths to manufacture high-quality single crystal perovskites for next-generation optoelectronic devices.