Xu Bin, Li Yawen, Hong Peibin, Zhang Peijie, Han Jiang, Xiao Zewen, Quan Zewei
Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong, China.
Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan, Hubei, China.
Nat Commun. 2024 Aug 27;15(1):7403. doi: 10.1038/s41467-024-51836-2.
Hybrid metal halides represent a novel type of semiconductor light emitters with intriguing excitonic emission properties, including free exciton emission and self-trapped exciton emission. Achieving precise control over these two excitonic emissions in hybrid metal halides is highly desired yet remains challenging. Here, the complete transformation from intrinsically broadband self-trapped exciton emission to distinctively sharp free exciton emission in a quasi-one-dimensional hybrid metal halide (CHN)[PbBr]·6Br with a ribbon width of n = 4, is successfully achieved based on high-pressure method. During compression, pressure-induced phonon hardening continuously reduces exciton-phonon coupling, therefore suppressing excitonic localization and quenching the original self-trapped exciton emission. Notably, further compression triggers excitonic delocalization to induce intense free exciton emission, accompanied with reduced carrier effective masses and improved charge distribution. Controlled high-pressure investigations indicate that the ribbon width of n > 2 is necessary to realize excitonic delocalization and generate free exciton emissions in similar quasi-one-dimensional hybrid metal halides. This work presents an important photophysical process of excitonic transitions from self-trapped exciton emission to free exciton emission in quasi-one-dimensional hybrid metal halides without chemical regulation, promoting the rational synthesis of hybrid metal halides with desired excitonic emissions.
混合金属卤化物是一种新型的半导体发光体，具有引人入胜的激子发射特性，包括自由激子发射和自陷激子发射。实现对混合金属卤化物中这两种激子发射的精确控制是非常有必要的，但仍然具有挑战性。在此，基于高压方法，在具有n = 4的带状宽度的准一维混合金属卤化物(CHN)[PbBr]·6Br中，成功实现了从本质上宽带的自陷激子发射到明显尖锐的自由激子发射的完全转变。在压缩过程中，压力诱导的声子硬化不断降低激子-声子耦合，从而抑制激子局域化并淬灭原始的自陷激子发射。值得注意的是，进一步压缩会触发激子离域，从而诱导强烈的自由激子发射，同时伴随着载流子有效质量的降低和电荷分布的改善。可控的高压研究表明，n > 2的带状宽度对于在类似的准一维混合金属卤化物中实现激子离域并产生自由激子发射是必要的。这项工作展示了在无需化学调控的情况下，准一维混合金属卤化物中激子从自陷激子发射到自由激子发射的重要光物理过程，促进了具有所需激子发射的混合金属卤化物的合理合成。
