Manipulating the sublattice distortion induced by Mn2+ doping for boosting the emission characteristics of self-trapped excitons in Cs4SnBr6

The fundamental photophysics involved in the doping effect of zero-dimensional (0D) lead-free tin-halide perovskites (Cs4SnX6, X = Br and I), especially the dynamics of self-trapped excitons (STEs), is crucial for their practical applications. Here, we proposed the use of Mn2+ doping to realize efficient emission from the STEs in Cs4SnBr6. The Mn2+-doped Cs4SnBr6 exhibits an enhanced photoluminescence (PL) quantum yield of up to similar to 75.8%, a broadened emission spectrum, and improved thermal stability. The experimental observations combined with first-principles calculations reveal that the significant PL enhancement originates from the enhanced electron-phonon coupling and the increased binding energies of STEs, as a consequence of the large distortion of [SnBr6](4-) octahedra induced by Mn2+ doping. In addition, it was verified that the color tuning of Mn2+-doped Cs4SnBr6 is achieved by the competitive transfers of free excitons to STE states and Mn2+ sites based on time-resolved and temperature-dependent PL measurements. The Mn2+-doped Cs4SnBr6 assembled into commercial UV-LED chips exhibits strong white light emission with a color temperature of 6346 K. Our findings not only provide deep insight into the dynamics of STEs in Mn2+-doped Cs4SnBr6 but also open new horizons for manipulating and optimizing the emission of STEs in 0D perovskites, thereby laying a foundation for developing white LEDs based on 0D perovskites.

Automated summary

In this study, efficient emission of self-trapped excitons (STEs) in Mn2+-doped Cs4SnBr6 was achieved, leading to an improved photoluminescence quantum yield and thermal stability. Experimental and computational results showed that Mn2+ doping induced distortion of [SnBr6](4-) octahedra, enhancing the electron-phonon coupling and binding energies of STEs, thereby significantly enhancing the emission intensity. The color tuning mechanism of Mn2+-doped Cs4SnBr6 was verified through time-resolved and temperature-dependent photoluminescence measurements. When assembled into commercial UV-LED chips, Mn2+-doped Cs4SnBr6 exhibited strong white light emission with a color temperature of 6346 K. This research provides deep insights into the dynamics of STEs in Mn2+-doped Cs4SnBr6 and paves the way for developing white LEDs based on 0D perovskites.