Study of electroluminescence and photophysical properties of single halide perovskite nanocrystals

单卤化物钙钛矿纳米晶的电致发光和光物理性质研究

基本信息

批准号：
19H02684
负责人：
VACHA Martin
金额：
$ 11.48万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2019
资助国家：
日本
起止时间：
2019-04-01 至 2024-03-31
项目状态：
已结题

项目摘要

In the past year, the research on the mechanism and methods of suppression of PL blinking included ligand engineering of the CsPbBr3 nanocrystals. Focus was placed on reproducibility of the nanocrystal synthesis and ligand exchange, as well as on the effect of the ligands on the nanocrystal aging. Further, a series of mixed cation (MA/FA) hybrid organo-metallic halide perovskite films were fabricated and their nanoscale properties were studied using PL microspectroscopy. PL spectra measured on sub-micrometer revealed large compositional heterogeneity of the films. The heterogeneity was largest for the FA 50% fraction films which contain purely MA domains, purely FA domains, as well as domains composed of mixed MA/FA cations of varying ratios. The films also showed PL blinking which reflects dynamic non-radiative quenching. The quenching was most suppressed for the FA 50% films which indicates that the truly mixed MA/FA domains are least affected by the non-radiative losses. Further, the PL blinking was correlated between locations that are several micrometers apart, indicating that the grain boundaries do not represent barriers for charge transport and do not work as charge traps, enabling efficient charge migration over micrometer distances. The blinking behavior was also affected by externally applied electric field, which additionally causes large fluctuations of PL spectra that are explained by field-induced I- ion migration.

在过去的一年里，抑制PL闪烁的机制和方法的研究包括CsPbBr3纳米晶的配体工程。重点关注纳米晶体合成和配体交换的再现性，以及配体对纳米晶体老化的影响。此外，还制备了一系列混合阳离子（MA/FA）杂化有机金属卤化物钙钛矿薄膜，并使用 PL 显微光谱研究了它们的纳米级特性。在亚微米上测量的 PL 光谱显示薄膜的成分存在很大的异质性。对于包含纯 MA 域、纯 FA 域以及由不同比例的混合 MA/FA 阳离子组成的域的 FA 50% 分数膜，异质性最大。这些薄膜还显示出 PL 闪烁，这反映了动态非辐射猝灭。 FA 50% 薄膜的猝灭受到最大程度的抑制，这表明真正混合的 MA/FA 域受非辐射损失的影响最小。此外，PL 闪烁与相隔几微米的位置之间存在相关性，这表明晶界并不代表电荷传输的障碍，也不会充当电荷陷阱，从而能够在微米距离上实现有效的电荷迁移。眨眼行为还受到外部施加的电场的影响，这另外导致 PL 光谱的大幅波动，这可以通过场诱导的 I 离子迁移来解释。