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Size-Dependent Phase Transition in Perovskite Nanocrystals
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2019-08-29 00:00:00 , DOI: 10.1021/acs.jpclett.9b02058
Lige Liu 1, 2 , Ru Zhao 3, 4 , Changtao Xiao 3 , Feng Zhang 3 , Federico Pevere 2 , Kebin Shi 1 , Houbing Huang 3, 4 , Haizheng Zhong 3 , Ilya Sychugov 2
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2019-08-29 00:00:00 , DOI: 10.1021/acs.jpclett.9b02058
Lige Liu 1, 2 , Ru Zhao 3, 4 , Changtao Xiao 3 , Feng Zhang 3 , Federico Pevere 2 , Kebin Shi 1 , Houbing Huang 3, 4 , Haizheng Zhong 3 , Ilya Sychugov 2
Affiliation
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The complex structure of halide and oxide perovskites strongly affects their physical properties. Here, the effect of dimensions reduced to the nanoscale has been investigated by a combination of single-dot optical experiments with a phase transition theory. Methylammonium lead bromide (CH3NH3PbBr3) nanocrystals with two average particle sizes of ∼2 and ∼4 nm with blue and green photoluminescence, respectively, were spectrally and temporally probed on a single-particle level from 5 to 295 K. The results show that the abrupt blue shift of the photoluminescence spectra and lifetimes at ∼150 K can be attributed to the cubic-to-tetragonal phase transition in the large 4 nm nanocrystals, while this phase transition is completely absent for the small 2 nm particles in the investigated temperature range. Theoretical calculations based on Landau theory reveal a strong size-dependent effect on temperature-induced phase transitions in individual CH3NH3PbBr3 nanocrystals, corroborating experimental observations. This effect should be considered in structure–property analysis of ultrasmall perovskite crystals.
中文翻译：
钙钛矿纳米晶体中尺寸依赖的相变
卤化物和氧化物钙钛矿的复杂结构极大地影响了它们的物理性能。在这里，通过将单点光学实验与相变理论相结合，研究了尺寸减小至纳米级的影响。甲基铵溴化铅（CH 3 NH 3 PbBr 3）分别在5和295 K的单粒子水平上光谱和时间探测分别具有〜2和〜4 nm两种平均粒径的蓝色和绿色光致发光的纳米晶体。结果表明，光致发光的突然蓝移约150 K的光谱和寿命可归因于大的4 nm纳米晶体中的立方到四方相变，而在所研究的温度范围内，对于2 nm的小颗粒则完全不存在这种相变。基于Landau理论的理论计算表明，单个CH 3 NH 3 PbBr 3对温度诱导的相变具有很强的尺寸依赖性。纳米晶体，证实了实验观察。在超小型钙钛矿晶体的结构-性质分析中应考虑这种效应。
更新日期：2019-08-29
中文翻译：
钙钛矿纳米晶体中尺寸依赖的相变
卤化物和氧化物钙钛矿的复杂结构极大地影响了它们的物理性能。在这里，通过将单点光学实验与相变理论相结合，研究了尺寸减小至纳米级的影响。甲基铵溴化铅（CH 3 NH 3 PbBr 3）分别在5和295 K的单粒子水平上光谱和时间探测分别具有〜2和〜4 nm两种平均粒径的蓝色和绿色光致发光的纳米晶体。结果表明，光致发光的突然蓝移约150 K的光谱和寿命可归因于大的4 nm纳米晶体中的立方到四方相变，而在所研究的温度范围内，对于2 nm的小颗粒则完全不存在这种相变。基于Landau理论的理论计算表明，单个CH 3 NH 3 PbBr 3对温度诱导的相变具有很强的尺寸依赖性。纳米晶体，证实了实验观察。在超小型钙钛矿晶体的结构-性质分析中应考虑这种效应。
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