Xu Bin, Li Qian, Han Jiang, Chen Zhongwei, Luo Zhishan, Chen Yulin, Quan Zewei
Department of Chemistry, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, China.
School of Physics Science and Information Technology, Shandong Key Laboratory of Optical Communication Science and Technology, Liaocheng University, Liaocheng, Shandong 252000, China.
J Chem Phys. 2024 May 21;160(19). doi: 10.1063/5.0205703.
Zero-dimensional (0D) hybrid metal halides (HMHs) have emerged as a promising platform for exploring excitation-dependent multicolor luminescent materials owing to their diverse crystal structures and chemical compositions. Nevertheless, understanding the mechanism behind excitation-dependent emissions (EDEs) in 0D HMHs and achieving precise modulation remains challenging. In this work, the delicate regulations on the EDE of 0D (DMEDABr)4SnBr3I3 (DMEDA: N, N'-dimethylethylenediamine) with mixed halogens are achieved under low temperature and high pressure, respectively. The inhomogeneous halogen occupation at the atomic scale leads to the formation of Br-rich and I-rich SnX6 (X = Br, I) octahedra, which act as distinct luminescent centers upon photoexcitation. At low temperatures, the narrowed photoluminescence spectra could distinguish the individual emissions from different luminescent centers, resulting in a pronounced EDE of (DMEDABr)4SnBr3I3. In addition, the contraction and distortion of the luminescent SnX6 (X = Br, I) centers at high pressure further result in different degrees of emission shifts, giving rise to the gradual emergence and disappearance of EDE. This work elucidates the underlying mechanism of EDE in 0D HMHs and highlights the crucial role of halogens in determining the optical properties of metal halides.
零维（0D）混合金属卤化物（HMHs）因其多样的晶体结构和化学成分，已成为探索激发依赖型多色发光材料的一个有前景的平台。然而，理解0D HMHs中激发依赖型发射（EDEs）背后的机制并实现精确调制仍然具有挑战性。在这项工作中，分别在低温和高压条件下实现了对具有混合卤素的0D（DMEDABr）4SnBr3I3（DMEDA：N，N'-二甲基乙二胺）的EDE的精细调控。原子尺度上不均匀的卤素占据导致形成富Br和富I的SnX6（X = Br，I）八面体，它们在光激发时充当不同的发光中心。在低温下，变窄的光致发光光谱可以区分来自不同发光中心的单独发射，从而导致（DMEDABr）4SnBr3I3出现明显的EDE。此外，高压下发光的SnX6（X = Br，I）中心的收缩和畸变进一步导致不同程度的发射位移，从而使EDE逐渐出现和消失。这项工作阐明了0D HMHs中EDE的潜在机制，并突出了卤素在决定金属卤化物光学性质方面的关键作用。
