Tan Jieyao, Jiang Xingxing, Liu Dongyu, Moghaddam Ahmad Ostovari, Stolyarov Vasily S, Xiao Shifang, Vasenko Andrey S
College of Physics and Electronics Engineering, Hengyang Normal University, Hengyang 421002, China.
HSE University, Moscow 101000, Russia.
J Chem Phys. 2024 Oct 14;161(14). doi: 10.1063/5.0231090.
Broadband blue emission in zero-dimensional perovskites has received considerable attention, which is very important for the realization of stable blue-light emitters; however, the underlying formation mechanism remains unclear. Based on first-principles calculations, we have systematically studied the self-trapped excitons (STEs) behavior and luminescence properties in 0D-(DMA)4PbI6 perovskite. Our calculations show that there is a significant difference between the intrinsic STE luminescence mechanism (∼2.51 eV) and experimental observations (∼2.70 eV). In contrast, we found that the iodine vacancy (VI) is energetically accessible and exhibits a shallow charge transition level at ∼2.69 eV (0/+1) above the valence band maximum, which provides the initial local well for the STEs formation. Moreover, the low electronic dimension synergistic Jahn-Teller distortion facilitates the formation of extrinsic excitons self-trapping. Further excited state electronic structure analysis and configuration coordinate diagram calculations confirmed that the broadband blue emission in 0D-(DMA)4PbI6 is the origin of VI-induced extrinsic STEs instead of intrinsic STEs. Therefore, our simulation results rationalize the experimental phenomena and provide important insights into the formation mechanism of STEs in low-dimensional perovskite systems.
零维钙钛矿中的宽带蓝光发射受到了广泛关注，这对于实现稳定的蓝光发射体非常重要；然而，其潜在的形成机制仍不清楚。基于第一性原理计算，我们系统地研究了零维（DMA）4PbI6钙钛矿中的自陷激子（STE）行为和发光特性。我们的计算表明，本征STE发光机制（约2.51 eV）与实验观测值（约2.70 eV）之间存在显著差异。相比之下，我们发现碘空位（VI）在能量上是可及的，并且在价带最大值上方约2.69 eV（0/+1）处表现出一个浅电荷跃迁能级，这为STE的形成提供了初始局部阱。此外，低电子维度协同 Jahn-Teller 畸变促进了非本征激子自陷的形成。进一步的激发态电子结构分析和组态坐标图计算证实，零维（DMA）4PbI6中的宽带蓝光发射是由VI诱导的非本征STE而非本征STE产生的。因此，我们的模拟结果合理解释了实验现象，并为低维钙钛矿系统中STE的形成机制提供了重要见解。
