Single-Component White Light Emitting CdSexSy Alloy Nanocrystals Through Phosphine-Free Route

Semiconductor nanocrystals are promising for display and lighting devices. Herein, we report a facile one-pot synthetic route to fabricate white light emitting CdSexSy nanocrystals with enhanced quantum yield using CdO, S powder, and Se powder as precursors. The phosphine-free route was adopted, employing paraffin oil as the reducing agent and solvent for the fabrication. The optical properties can be effectively tailored by controlling the reaction time and the molar ratio of Se/S. The emission of pristine CdSexSy nanocrystals covered a broad visible range from 400 to 750 nm. The CdSexSy nanocrystals (Se/S = 0.4) exhibited white-light emission with quantum yield of 50 ± 3 % and Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.30, 0.31). The band-edge (~400-450 nm) to trap-state (~550-750 nm) emissions was tuned by controlling the Se/S ratio, and the different shades of white light were obtained. Furthermore, the quantum yield and CIE coordinates of the CdSexSy nanocrystals (Se/S = 0.4) were found to be similar even after 30 days of fabrication, showing the high stability of nanocrystals. The white light emission was retained in nanocrystals-embedded poly(methyl methacrylate) (PMMA) thin film and also in the hydrogel matrix. The one-pot, low-cost, scalable fabrication of white light emitting CdSexSy nanocrystals demonstrated in the present study offers promising scope in the solid-state display applications.