Intrinsic broadband photoluminescence (PL) of self-trapped excitons (STEs) are systematically studied in lead-free double perovskite nanocrystals (NCs). It is clarified that bandgap (direct/indirect) has important influence on the PL properties of STEs: indirect bandgap NCs exhibit strong exciton-phonon coupling which results in non-radiative STEs, while direct bandgap NCs exhibit moderate exciton-phonon coupling, inducing bright STE PL. Furthermore, by alloying K⁺ and Li⁺ ions in Cs₂AgInCl₆ NCs, the NCs exhibit broadband white-light emission. Charge-carrier dynamics study indicates that the efficient white-light emission originates from the further suppressed non-radiative processes of the STEs in the direct bandgap structure. This work may deepen the understanding of STEs and guide the design of high-performance lead-free perovskites.

在无铅双钙钛矿纳米晶体 (NC) 中系统地研究了自陷激子 (STE) 的本征宽带光致发​​光 (PL)。阐明了带隙（直接/间接）对 STE 的 PL 特性有重要影响：间接带隙 NC 表现出强烈的激子-声子耦合，导致非辐射 STE，而直接带隙 NC 表现出适度的激子-声子耦合，诱导明亮STE PL。此外，通过将Cs ₂ AgInCl _{6中的 K} ⁺和 Li ^{+离子合金化}NCs，NCs表现出宽带白光发射。电荷载流子动力学研究表明，有效的白光发射源于直接带隙结构中 STE 的非辐射过程的进一步抑制。这项工作可能会加深对 STE 的理解，并指导高性能无铅钙钛矿的设计。