High quality and large size bulk single crystals are essential to study the basic properties of perovskite materials and their performance limits of X-ray detection and imaging.In this paper,high quality MAPbI3 and MAPbCl3 single crystals were prepared using the silicone-oil assisted method and the properties and the performance of the single crystals and the corresponding X-ray detectors were characterized.These performances of single crystals grown with the silicone-oil assisted method are better than those prepared with the inverse temperature crystallization method(ITC).The ITC,as one of the most pre-vailing crystal growth methods,has drawbacks over the control of the nucleation and the growth rate.Silicone-oil assisted method was recently developed to overcome the above drawbacks and grew the perovskite single crystals in a controllable manner.In the silicone-oil assisted method,a capping layer on the precursor is adopted to reduce the solvent evaporation rate to a certain level and thus to manage the precursor in a slightly supersatura-ted condition.Silicone oil is selected as the capping layer for its smaller density and the insol-ubility with the precursor.The solvent in precursor will diffuse through the silicone oil cap-ping layer and evaporate into the air at the silicone oil/air interface,driven by the content difference and the saturation vapor pressure,respectively.The silicone-oil assisted method realizes the constant growth of perovskite single crystals,since the driving force of the crystallization relies on the solvent diffusion rate but not the temperature-depended solubility.During the perovskite crystal growth process,the precursor is at a steady condi-tion(constant temperature and constant concentration)in majority of the time.According to the classic growth theory,single crystals grown at a constant rate will have better crystal quality.Indeed,MAPbI3 single crystals grown with the silicone-oil assisted method have a FWHM of rocking curves of(110)crystal planes of 0.011 2°,the fluorescence lifetime of 1 022 ns,and the lowest defect density of 5.61×109 cm-3.MAPbCl3 single crystals grown with the silicone-oil assisted method have a FWHM of rocking curves of(10 0)crystal planes of 0.014 3°,the fluorescence lifetime of 957 ns,and the lowest defect density of 3.57×109 cm 3.The X-ray detector based on MAPbI3 single crystals has a high sensitivity of 7 300 μC/(Gy·cm2).All results indicate that this silicone-oil assisted growth method is suitable for the mass production of high-quality single crystals for radiation detection.
关键词
钙钛矿单晶/晶体生长/硅油辅助法/X射线探测器
Key words
perovskite single crystal/crystal growth/silicone-oil assisted method/X-ray detector
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