Ultra pure orange-emitting Sn:CuBr quantum dots for LED applications

We report a facile, cost-effective, and environmental friendly supersaturated recrystallization method for synthesizing Copper (I) bromide quantum dots (CuBr QDs) at room temperature under ambient conditions. The synthesis of CuBr QDs and their optical behaviour under weak confinement remains largely unexplored, where CuBr is a non-toxic, earth-abundant semiconductor with intrinsic blue emission and promising optoelectronic properties. The optical properties of the synthesised QDs were tuned by tin (Sn) doping. Structural analysis confirmed the formation of phase-pure, crystalline QDs with an average particle size of 2.98 ± 0.44 nm for pure and 3.57 ± 0.39 nm for Sn-doped CuBr QDs. The X-ray photoelectron spectroscopy confirmed the oxidation state Formula: see text, Formula: see text, and Formula: see text and verified the successful incorporation of Sn into the CuBr lattice. Optical characterization shows an increase in bandgap from transitioning from bulk to QDs, resulting in blue emission, while Sn doping introduces dopant-related states that decrease the bandgap, causing a red-shift in emission color from blue to orange. This is accompanied by an extended photoluminescence lifetime from 490 ps to 970 ps and enhanced color purity up to 99.7%. These findings highlight the potential of Sn-doped CuBr QDs as efficient, eco-friendly candidates for orange-emitting solid-state lighting applications.