Jin Yu, Rusishvili Mariami, Govoni Marco, Galli Giulia
Department of Chemistry, University of Chicago, Chicago, Illinois 60637, United States.
Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States.
J Phys Chem Lett. 2024 Mar 28;15(12):3229-3237. doi: 10.1021/acs.jpclett.4c00209. Epub 2024 Mar 15.
We present a theoretical study of the formation of self-trapped excitons (STEs) and the associated broadband emission in metal-halide perovskites CsSnBr and CsAgInCl, using time-dependent density functional theory (TDDFT) with the dielectric-dependent hybrid (DDH) functional. Our approach allows for an accurate description of the excitonic effect and geometry relaxation in the electronic excited states and yields optical gap, STE emission energy, and emission spectra in reasonable agreement with experiments. We point out the significance of considering geometry relaxations in the electronic excited state by showing that the exciton-phonon coupling computed in the ground-state atomic geometry is insufficient to describe the physical properties of STEs. Overall, we find that TDDFT with the DDH hybrid functional is a suitable approach for the study of the formation of STEs in perovskite and provides insights for designing metal-halide perovskites with tailored emission properties.
我们使用含介电常数依赖的杂化（DDH）泛函的含时密度泛函理论（TDDFT），对金属卤化物钙钛矿CsSnBr和CsAgInCl中自陷激子（STE）的形成及相关宽带发射进行了理论研究。我们的方法能够准确描述电子激发态中的激子效应和几何弛豫，并给出与实验结果合理相符的光学带隙、STE发射能量和发射光谱。通过表明在基态原子几何结构中计算的激子 - 声子耦合不足以描述STE的物理性质，我们指出了考虑电子激发态几何弛豫的重要性。总体而言，我们发现采用DDH杂化泛函的TDDFT是研究钙钛矿中STE形成的合适方法，并为设计具有定制发射特性的金属卤化物钙钛矿提供了见解。
