期刊
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
卷 10, 期 18, 页码 5451-5457出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.jpclett.9b02058
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资金
- Swedish Foundation for International Cooperation in Research and Higher Education (STINT)
- China Scholarship Council (CSC)
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 similar to 2 and similar to 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 similar to 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.
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