Doped all-inorganic cesium zirconium halide perovskites with high-efficiency and tunable emission

Doping enables manipulation of both the electrical and optical properties of halide perovskites. Herein, we incorporated Te4+ into Cs2ZrCl6 single crystal, simultaneously preserving the vacancy-ordered structure, to obtain an efficient yellow-emitting perovskite with a near-unity photoluminescence quantum yield (PLQY ≈ 97.6%). Te4+ doping modifies the hue and emission color of pristine Cs2ZrCl6, generates new absorption channels, and successfully extends the excitation energy from < 280 nm to 360–450 nm range. Detailed spectral characterizations, including ultrafast femtosecond transient absorption measurements, reveal that the bright yellow light is derived from triplet self-trapped excitons. Moreover, further tuning doping concentration enables Te-doped Cs2ZrCl6 single crystals to exhibit efficient warm white light emission. This work provides a new perspective for the development and design of stable lead-free perovskites with highly efficient luminescence.