The Growth And Photoelectrical Properties Of MAPbX₃(X=I,Br,Cl) Single Crystals

Organic-inorganic hybrid lead halide perovskites have attracted intensive interest from both academic and industrial communities for their outstanding photoelectronic performances in solar cells,light-emitting diodes,photodetectors,and lasers.The prominent advantages,such as large absorption,high carrier mobility,long carrier lifetime,and long carrier diffusion length,suggest hybrid lead halide perovskites as excellent candidates in optoelectrical devices.However,the complicated internal structure of hybrid lead halide perovskites results in unusual carrier transport properties under various bias and illumination,such as strong hysteresis behaviors and slow photoresponse,which crucially influence the properties of optoelectrical device.On the other hand,high-quality perovskite single crystals show promising potential in optoelectrical devices due to the advantages of no grain boundaries,low defect density,long stability,longer carrier diffusion length,and narrower bandgap.Therefore,the MAPbX₃(X=I,Br,Cl)single crystals with large size and high quality were grown,and then the carrier transport properties were studied systematic.We prepared the perovskite-based detectors and the detection performance were studied.The main contents are shown as following:(1)The MAPbX₃(X=I,Br,Cl)single crystals were grown by improved inversion temperature crystallization(ITC)method,the size was 15mm×14mm×6mm(?7 days)for MAPbI₃,12mm×12mm×5mm(?7 days)for MAPbBr₃ and 8mm×8mm×3mm(?5 days)for MAPbCl₃.Partilularly,the growing speed and crystal size of MAPbCl₃ is highly improved compared to the reported values.The structure parameters including the crystal face,absorption edge,optical band gap,and photoluminescence emission peak were obtained by X-ray differaction,UV-vis spectrum and steady-state photoluminescence spectrum.It shows high quality perovskite single crystals were obtained.(2)We polished the(100)facet and then deposited with planar Au electrodes.The hysteresis and photoresponse properties of MAPbX₃(X=I,Br,Cl)single crystals were investigated systematically at various external biases both in dark and under light illumination.Our experimental results demonstrate clearly that the defect trapping,the rotation of MA⁺dipoles and the ion migration influence the charge transport dynamics in different regimes.The influences of these factors on MAPbX₃(X=I,Br,Cl)single crystals are different,resulting in special electrical properties in the MAPbX₃(X=I,Br,Cl)single crystals,respectively.(3)The MAPbX₃(X=I,Br,Cl)single crystal detector devices were prepared by depositing interdigital electrode.We investigated the detector performance,such as responsivity,external quantum efficiency and,detectivity under ultraviolet light with the wavelength of 365 nm and 254nm,respectively,which are helpful for the further development of perovskite-based detector.