Scalable Open-Air Synthesis of Mg2+-Doped Lead-Free Cs3Cu2Cl5 Nanocrystals for High-Performance Green LEDs

Cs 3 Cu 2 Cl 5 nanocrystals (NCs) have emerged as promising optoelectronic materials owing to their efficient self-trapped exciton (STE) emission. However, their limited environmental stability has significantly constrained their application in light-emitting diodes (LEDs). In this work, a facile ambient-air synthesis strategy is developed for Mg 2 ⁺-doped Cs 3 Cu 2 Cl 5 NCs that simultaneously addresses both stability and emission efficiency challenges. Remarkably, optimal Mg 2 ⁺ doping (20%) enhances the photoluminescence quantum yield (PLQY) from 28.69% to 59.3%. Comprehensive theoretical investigations through density of states (DOS) calculations and ab initio molecular dynamics (AIMD) simulations demonstrate that Mg 2 ⁺ doping induces bandgap narrowing for enhanced radiative recombination while reinforcing the crystal lattice stability. When integrated with a UV LED chip, the optimized NCs enable the fabrication of high-performance green LEDs exhibiting outstanding luminance (17 281 cd m − 2 ) and excellent color stability (CIE coordinates: 0.354, 0.518). This study provides not only a practical synthetic approach for stable copper halide NCs but also valuable insights for designing efficient STE emitters for optoelectronic applications.