Li Qian, Xu Bin, Quan Zewei
Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, P. R. China.
School of Physics Science and Information Technology, Shandong Key Laboratory of Optical Communication Science and Technology, Liaocheng University, Liaocheng, Shandong 252000, P. R. China.
Acc Chem Res. 2023 Nov 21;56(22):3282-3291. doi: 10.1021/acs.accounts.3c00537. Epub 2023 Oct 27.
ConspectusEmergent metal halides are generating significant interest as novel optical materials, and their diverse applications have brought them to the spotlight of chemistry and material science. The optical properties of semiconducting metal halides are fundamentally dominated by excitonic transitions, which refer to the complex processes of excitonic formation, self-trapping, as well as subsequent transitions of intersystem crossing (ISC) and internal conversion (IC). In this regard, high pressure has recently opened a new research dimension to regulate excitonic transitions in metal halides via continuous structural modulations, to understand the intriguing excitonic emissions from a new perspective. In this Account, we aim to rationalize the fundamental strategy for modulating and optimizing the optical properties of metal halides based on delicate exciton regulation via high-pressure method. First, the band gaps of metal halides that are directly related to the efficiency of excitonic formation, are accurately modulated through contraction, distortion, and destruction of metal-halogen polyhedra under compression. Then, considerable enhancement of self-trapped exciton emission is demonstrated by inducing proper polyhedral distortions via high-pressure method. Furthermore, the emission energy of metal halides could also be controllably and widely tuned through pressure-modulated excitonic transitions. Upon compression on different metal halides, excitonic IC is promoted with sufficient polyhedral distortions, and different sets of ISC could also be achieved. In the end, we emphasize the significance of high-pressure investigations in uncovering the complex excitonic transitions in emergent metal halides and predicting novel metal halides with desired optical properties at ambient conditions. It is expected that these discussions could inspire researchers in different fields to perform interdisciplinary high-pressure studies on novel functional materials.
综述
新兴金属卤化物作为新型光学材料正引起广泛关注，其多样的应用使其成为化学和材料科学领域的焦点。半导体金属卤化物的光学性质从根本上由激子跃迁主导，激子跃迁指的是激子形成、自陷以及随后的系间窜越（ISC）和内转换（IC）等复杂过程。在这方面，高压最近开辟了一个新的研究维度，通过连续的结构调制来调控金属卤化物中的激子跃迁，从新的角度理解有趣的激子发射。在本综述中，我们旨在基于通过高压方法进行的精细激子调控，阐明调节和优化金属卤化物光学性质的基本策略。首先，通过压缩下金属 - 卤素多面体的收缩、畸变和破坏，精确调制与激子形成效率直接相关的金属卤化物的带隙。然后，通过高压方法诱导适当的多面体畸变，证明自陷激子发射有显著增强。此外，金属卤化物的发射能量也可以通过压力调制的激子跃迁进行可控且广泛的调节。对不同金属卤化物进行压缩时，随着足够的多面体畸变，激子IC被促进，并且也可以实现不同的ISC组合。最后，我们强调高压研究在揭示新兴金属卤化物中复杂的激子跃迁以及预测在环境条件下具有所需光学性质的新型金属卤化物方面的重要性。预计这些讨论能够激发不同领域的研究人员对新型功能材料进行跨学科的高压研究。
