Sb3+/Tb3+/Sm3+ triply doped Cs2NaScCl6 double perovskite toward high-quality white-light emission

Lead-free double perovskites (LFDPs) have attracted substantial research interest owing to their unique photoluminescence characteristics, low toxicity, and structural versatility. However, achieving efficient single-lattice white-light emission remains a formidable challenge due to the intrinsic difficulty of spectral tuning and the trade-off between luminescence efficiency and color quality in single-host systems. To address this issue, we developed a triple-doped rare-earth double perovskite system Cs 2 NaScCl 6 : Sb 3+ , Tb 3+ , Sm 3+ . Through a competitive energy transfer design, we achieved fine control over energy migration from Sb 3+ to Tb 3+ and Sm 3+ , enabling precise spectral modulation simply by adjusting the dopant concentrations. Steady-state and time-resolved photoluminescence (PL) spectroscopy clearly identified three energy transfer routes: Sb 3+ → Tb 3+ , Sb 3+ → Sm 3+ , and Tb 3+ → Sm 3+ , which collectively contribute to the tunable white-light emission. The optimized material exhibits outstanding thermal stability, retaining 88.1% of its initial emission intensity at 473 K. The Cs 2 NaScCl 6 : 1%Sb 3+ , 40%Tb 3+ , 8%Sm 3+ single crystal achieves a photoluminescence quantum yield (PLQY) of 40.90%. When fabricated into WLED devices, this phosphor delivers a color rendering index (CRI) of 85.1, a correlated color temperature (CCT) of 4278 K, and near-ideal CIE coordinates of (0.336, 0.306). Collectively, this work not only presents a high-performance single-host white-light emitter for solid-state lighting applications, but also offers a viable energy transfer design strategy for rare-earth-activated LFDPs, thereby advancing the development of eco-friendly perovskite materials for white-light-emitting devices.