Universal, predominant exciton transfer in perovskite nanocrystal solids

IF 6.8 2区材料科学 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Science China Materials Pub Date : 2024-07-17 DOI:10.1007/s40843-023-2854-7

Yuqing Luo (, ), Zhiya Dang (, ), Lingchen Meng (, ), Zelong Chen (, ), Zihao Li (, ), Tongtong Lu (, ), Xiaobin Rao (, ), Shuyuan Zhao (, ), Qi Sun (, ), Pingqi Gao (, )

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引用次数: 0

Abstract

Perovskite nanocrystal (PNC) solids are promising materials for optoelectronic applications. Recent studies have shown that exciton diffusion in PNC solids occurs via alternate exciton hopping (EH) and photon recycling (PR). The energy disorder induced by the size distribution is a common factor in PNC solids, and the impact of this energy disorder on the exciton diffusion remains unclear. Here, we investigated the exciton diffusion in CsPbBr₃ NC solids with a Gaussian size distribution of 11.2 ± 6.8 nm via steady and time-resolved photoluminescence (PL) spectroscopy with multiple detection bands in transmission mode. Our results indicated that exciton diffusion was controlled by a downhill transfer among the different energy sites through the disordered energy landscape, as confirmed by the accompanying low-temperature PL analysis. A detailed examination revealed that the acceptor distribution in tandem with the reabsorption coefficient determined the contribution of EH and PR to exciton transfer between different energy sites. Consequently, the exciton diffusion mechanism varied in PNC solids of different thicknesses: in a thin solid with a thickness of several hundred nanometers, the exciton transfer was dominated by efficient EH and PR from the high-energy sites to the lower-energy sites; in a few-micrometer-thick solid, transfer from the medium-energy sites toward the lower-energy sites also became prominent and occurred mainly through PR. These findings enhance the understanding of the vital role that the acceptor distribution plays in the exciton diffusion process in PNC solids, providing important insights for optoelectronic applications based on PNC solids. Our work also exploits the use of commonly available tools for in-depth exciton diffusion studies, which reveals the interior diffusion information that is usually hidden in surface sensitive PL imaging methods.

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过氧化物纳米晶固体中普遍的、占主导地位的激子转移

过氧化物纳米晶（PNC）固体是一种很有前途的光电应用材料。最近的研究表明，PNC 固体中的激子扩散是通过交替的激子跳跃（EH）和光子再循环（PR）发生的。尺寸分布引起的能量无序是 PNC 固体中的一个常见因素，而这种能量无序对激子扩散的影响仍不清楚。在此，我们通过稳定和时间分辨的光致发光（PL）光谱，以及透射模式下的多检测波段，研究了具有 11.2 ± 6.8 nm 高斯尺寸分布的 CsPbBr3 NC 固体中的激子扩散。我们的研究结果表明，激子扩散是通过无序能谱在不同能量点之间的下坡转移来控制的，这一点也得到了随附的低温光致发光分析的证实。详细的研究表明，受体分布与再吸收系数共同决定了 EH 和 PR 对不同能量点之间激子转移的贡献。因此，在不同厚度的 PNC 固体中，激子扩散机制各不相同：在厚度为几百纳米的薄固体中，激子转移主要是通过高效的 EH 和 PR 从高能位点转移到低能位点；在厚度为几微米的固体中，从中能位点向低能位点的转移也变得非常突出，而且主要是通过 PR 发生的。这些发现加深了人们对受体分布在 PNC 固体中激子扩散过程中所起重要作用的理解，为基于 PNC 固体的光电应用提供了重要启示。我们的工作还利用了常用工具进行深入的激子扩散研究，从而揭示了通常隐藏在表面敏感的 PL 成像方法中的内部扩散信息。

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来源期刊

Science China Materials Materials Science-General Materials Science

CiteScore

11.40

自引率

7.40%

发文量

949

期刊介绍： Science China Materials (SCM) is a globally peer-reviewed journal that covers all facets of materials science. It is supervised by the Chinese Academy of Sciences and co-sponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China. The journal is jointly published monthly in both printed and electronic forms by Science China Press and Springer. The aim of SCM is to encourage communication of high-quality, innovative research results at the cutting-edge interface of materials science with chemistry, physics, biology, and engineering. It focuses on breakthroughs from around the world and aims to become a world-leading academic journal for materials science.