Optimization Of Preparation Process And Characterization Of CsPbBr₃ Single Crystal

The all-inorganic halide perovskite CsPbBr₃ has large bandgap,high average atomic number,high resistivity and large carrier mobility lifetime product.It has been considered as one of the most promising next generation nuclear radiation detector material due to its excellent optoelectronic properties.The main work of this paper is to study the optimization of preparation process of CsPbBr₃single crystals and the detection performance of CsPbBr₃photodetectors.Firstly,the chemical co-precipitation method was utilized to synthesize CsPbBr₃powders and electronic dynamic gradient method（EDG）was used to grow CsPbBr₃ single crystals.The experimental results showed that the as-synthesized powders usually deviated from the theoretical stoichiometric ratio of 1:1:3 due to the complexity of the process and the difficulty of controlling process parameters.It was found that the powders contained by-products such as Cs Pb₂Br₅ and Cs₄Pb Br₆.Therefore,the CsPbBr₃crystal has poor quality.The crystal has an infrared transmittance of 60%and a resistivity value of 5.24×10⁷Ωcm.Theμτproducts of the crystal is about 1.96×10^-5cm²/V.The performance of the crystal cannot meet the basic requirements of high performance nuclear radiation detection.Then,we utilized an improved solid phase method to synthesize CsPbBr₃ powders by introducing a convection process before crystal growth.When the convection temperature gradient was 11°C/cm and the convection time was 5 hours,high crystal quality was obtained.The infrared transmittance of the crystal is close to 80%.Theμτproducts of the crystal is about 3.98×10^-4 cm²/V.The crystal has a resistivity value of 6.48×10⁹Ωcm.Therefore,the performance of the crystal meets the basic requirements of high performance nuclear radiation detectors.In addition,when the convection time is 8 hours or more,the crystals grow along the（110）plane（or their parallel planes）and show a preferred orientationFinally,we built a photodetector with Au/CsPbBr₃/Au structure.The detector has obvious detection response to 365nm pulsed laser.Its response signal-to-noise ratio can reach32 under 0.1V bias.The rising time and recovery time of the devices is 0.045s and 0.188s,respectively.The detector has a significant detection response to X-rays.When the radiation dose rate is 5.5m Gy_airS^-1,the response signal-to-noise ratio can reach 20 under an applied external bias of-1V.Under an applied external bias of-100V,the sensitivity of the detector can reach 4.186×10³μCGy^-1_aircm^-2.The detector has a certain detection response to ²⁴¹Am（5.48 Me V）α-ray.The single-signal response signal-to-noise ratio can reach 27 and the multi-channel spectral response has the energy resolution of about 27.8% under 300V bias.