Qin Chaochao, Jiang Zhinan, Zhou Zhongpo, Liu Yufang, Jiang Yuhai
Henan Key Laboratory of Infrared Materials & Spectrum Measures and Applications, School of Physics, Henan Normal University, Xinxiang 453007, China.
Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China.
Nanomaterials (Basel). 2021 Feb 11;11(2):463. doi: 10.3390/nano11020463.
CsPbBr3 has attracted great attention due to unique optical properties. The understanding of the multiexciton process is crucial for improving the performance of the photoelectric devices based on CsPbBr3 nanocrystals. In this paper, the ultrafast dynamics of CsPbBr3 nanocrystals is investigated by using femtosecond transient absorption spectroscopy. It is found that Auger recombination lifetime increases with the decrease of the excitation intensity, while the trend is opposite for the hot-exciton cooling time. The time of the hot-carriers cooling to the band edge is increased when the excitation energy is increased from 2.82 eV (440 nm) to 3.82 eV (325 nm). The lifetime of the Auger recombination reaches the value of 126 ps with the excitation wavelength of 440 nm. The recombination lifetime of the single exciton is about 7 ns in CsPbBr3 nanocrystals determined by nanosecond time-resolved photoluminescence spectroscopy. The exciton binding energy is 44 meV for CsPbBr3 nanocrystals measured by the temperature-dependent steady-state photoluminescence spectroscopy. These findings provide a favorable insight into applications such as solar cells and light-emitting devices based on CsPbBr3 nanocrystals.
CsPbBr3因其独特的光学性质而备受关注。理解多激子过程对于提高基于CsPbBr3纳米晶体的光电器件性能至关重要。本文利用飞秒瞬态吸收光谱研究了CsPbBr3纳米晶体的超快动力学。研究发现，俄歇复合寿命随激发强度的降低而增加，而热激子冷却时间的趋势则相反。当激发能量从2.82 eV（440 nm）增加到3.82 eV（325 nm）时，热载流子冷却到带边的时间增加。在激发波长为440 nm时，俄歇复合寿命达到126 ps。通过纳秒时间分辨光致发光光谱测定，CsPbBr3纳米晶体中单个激子的复合寿命约为7 ns。通过温度依赖的稳态光致发光光谱测量，CsPbBr3纳米晶体的激子结合能为44 meV。这些发现为基于CsPbBr3纳米晶体的太阳能电池和发光器件等应用提供了有益的见解。
