Cs₂Zr_1−xTe_xCl₆ Perovskite Microcrystals with Ultrahigh Photoluminescence Quantum Efficiency of 79.46% for High Light Efficiency White Light Emitting Diodes

Abstract Recently, lead‐free materials with stable photoluminescence (PL) at room temperature, such as vacancy‐ordered double perovskites have drawn wide attention. Herein, Te⁴⁺‐doped all‐inorganic lead‐free Cs₂Zr_1−xTe_xCl₆ perovskite microcrystals (MCs) are reported. The obtained pure Cs₂ZrCl₆ perovskite MCs exhibit a blue emission, while Cs₂Zr_1−xTe_xCl₆ perovskite MCs show a broad and strong yellow emission with ultrahigh photoluminescence quantum yield (PLQY) up to 79.46% at room temperature. The structure and optical properties of perovskite MCs are investigated in detail by experiments and theoretical calculations. The mechanism that ³P₁ of Te can be partially frozen at the low temperature regarding Cs₂Zr_1−xTe_xCl₆ perovskite MCs is proposed. White light emitting diodes (WLEDs) with a color coordinate of (0.344, 0.333), a correlated color temperature of 4959 K, a color rendering index (Ra) of 74.8, and a high light efficiency of 91.16 lm W⁻¹, are fabricated by the prepared Cs₂Zr_1−xTe_xCl₆ perovskite MCs powder with a commercial near‐UV LED (NUV‐LED) chip (450 nm). The results suggest that Te⁴⁺‐doped all‐inorganic lead‐free perovskite MCs show great potential in the next‐generation solid‐state lightings.