한양대학교 물리학과 BK-Four 양자물질 극한물성 교육연구팀 한양대학교 물리학과

1. 연수기간 : 2021. 03. 15 ~ 2021. 03. 19 (총 4박 5일) 

2. 연수국가 : 온라인 진행

3. 연수기관명 : APS Physics

4. 연수자 : 석박사통합과정 11기 참여대학원생 1명 

5. 연수주제 : Pressure-Induced the Purification of Cs₄PbBr₆ from CsPbBr₃ Impurity

    Lead halide perovskites have been of great interest due to their promising optoelectronic applications. While solution-based synthetic methods have been well developed, they often form mixtures of perovskites with several different phases, which cannot be easily purified by conventional purification methods. Here we report a high-pressure purification method of Cs₄PbBr₆ perovskite containing a trace amount of CsPbBr₃. The synthesized bulk Cs₄PbBr₆ perovskites exhibit strong photoluminescence at λ_peak = ~ 520 nm because of CsPbBr₃ embedded in Cs₄PbBr₆. Our approach utilized that CsPbBr3 crystals are sensitive to the change of pressure and make distortion of Pb-Br bonds at moderately low pressure, while Cs₄PbBr₆ crystals are much stable at high-pressure condition. With the application of high pressure (20 GPa), the crystalline CsPbBr₃ phase turns amorphous while the crystal structure of Cs₄PbBr₆ is retained without change. Almost 95% of the CsPbBr₃ phase can be removed by one cycle of compression. Cs₄PbBr₆ which originally shows strong green fluorescence becomes non-fluorescent after one cycle of compression. High-pressure compression can be used to selectively remove CsPbBr₃ by pressure-induced amorphization without depreciating the Cs₄PbBr₆ crystal structure.