Synergistic Effects of Zinc Thiocyanate on the Performance of Cesium Lead Bromide Perovskite Phosphors for Solid State Lighting Applications

All inorganic lead halide perovskites drove a new paradigm in the field of display and lighting technologies because of significant cost and performance advantage over the current state-of-the-art. However, the applications of these perovskites are undermined due to the toxicity and severe degradation of the materials in response to external stimuli. This research highlights the synergetic effects of co-doping of CsPbBr₃ nanocrystals (NCs) at its B- and X-site using zinc thiocyanate (Zn(SCN)₂). This is achieved by engineering different compositions of Zn(SCN)₂ (up to 80%). The adopted doping strategy helps to improve the photoluminescence stability of the pristine NCs when stored under ambient conditions for 156 days. The photoluminescence quantum yield (PLQY) is records a maximum (~ 92%) at 20 mol% of Zn(SCN)₂ and a minimum at 80 mol% ( ~ 40%). This is attributed to the improved local structural order and reduced inhomogeneous strain between the lattices of the NCs due to the synchronized effect of Zn²⁺ and SCN^–. The composite NCs are integrated as color-converting layers (thin 3D printing layer coated with NCs) in combination with a blue LED chip to obtain the white light. It exhibits bright white emissions with a color rendering index of 86, correlated color temperature of 6046 K, and color coordinates close to standard white light. This work emphasizes the strong potential of inexpensive and earth-abundant Zn(SCN)₂-based CsPbBr₃ composites to meet consumer needs.