Study On Synthesis,Photoelectric Properties Modulation And Application Of Rare Earth Doped Perovskite Single Crystals

In recent years,perovskite materials are considered as photoelectric materials with high application potential due to their large absorption coefficient,high photoluminescence quantum yield（PLQY）,high carrier mobility and long carrier diffusion length.In particular,perovskite single crystal is an ideal material for preparing high performance optoelectronic devices due to its incomparable advantages over polycrystalline materials.However,there are still many deficiencies:1.The crystal quality of single crystal is still not ideal,and the long-term stability of the devices is relatively low.2.The photoelectric application of most materials in near infrared spectrum is restricted due to the large bandgap.3.3D perovskite single crystal show serious self-absorption and poor PLQY induced by its large size,and small Stokes shift,which critically limits the further improvement of the photoelectric devices.Currently,doping can effectively improve the optical properties of perovskite materials.In this paper,the photoelectric properties of perovskite single crystals are tuned by rare earth ion doping,expanding their applications.Specific research contents and innovations are as follows:（1）We develop a high pressure solvothermal method to dope a series of rare earth ions into MAPbI₃ single crystals,which successfully solved the difficult problem of preparation for rare-earth doped organic-inorganic hybrid perovskite materials.Rare earth ions doping not only broadens the emission spectrum of MAPbI₃,but also largely improves their conductivity,carrier mobility and stability.In addition,the detector based on rare earth doped MAPbI₃ realizes multi-band response to visible,near infrared light and X-ray.The performance of photodetectors is largely improved,exhibiting high detectivity of 0.7-3.8×10¹²Jones for broad band（350-850 nm）,0.6-1.1×10¹¹Jones for two NIR bands（980 nm,1540 nm）,and sensitivity of 1.16×10⁶μC Gy_air^-1cm^-2for X-ray detection.（2）We develop a high pressure solvothermal method to successfully dope a series of rare earth ions into CsPbCl₃ single crystals,and effectively tune their photoelectric properties and stability.Particularly,the emission spectrum of CsPbCl₃:Yb³⁺single crystals are successfully broadened,and PLQY is significantly improved.Material exhibits higher carrier mobility(36.16 cm²V^-1s^-1),and lower defect state density(0.95×10⁹cm^-3),which are 300 times and 7 times of that of thin film materials,respectively.In addition,the high-performance X-ray detector based on CsPbCl₃:Yb³⁺achieves a high sensitivity of 87941μC Gy_air^-1cm^-2,which is 6.6 times than that of CsPbCl₃X-ray detector.This work successfully solved the problems that CsPbCl₃nanocrystalline thin films are difficult to be used in X-ray detection.（3）The CsPbCl_1.5Br_1.5:Yb³⁺single crystals with PLQY of 149%and a Stokes-shift>500 nm are obtained by adjusting the ratio of halogen ions in CsPbCl_xBr_3-x:Yb³⁺.The high-performance scintillator based on CsPbCl_1.5Br_1.5:Yb³⁺exhibits high transmittance,high X-ray absorption/conversion efficiency,high light yield（118400 photons/MeV）and low detection limit(165.6 nGy_airs^-1).In addition,the imaging system based on the detector display a clear and high contrast X-ray single pixel images.This work successfully solved the problems of low PLQY and serious self-absorption of 3D perovskite single crystal materials.