One-Pot Phosphine-Free Route for Single-Component White Light Emitting CdSe x S y Alloy Nanocrystals

• Published in: ACS sustainable chemistry & engineering 2021-04, Vol.9 (16), p.5613-5622
• Main Authors: Jaiswal, Shilpi, Pathak, Jyotsana, Kundu, Subhankar, Patra, Abhijit
• Format: Article
• Language: English
• ISSN: 2168-0485; 2168-0485
• DOI: 10.1021/acssuschemeng.1c00245

In an enduring quest to develop highly efficient display and lighting devices over the decades, semiconductor nanocrystals have recently emerged as favorable candidates. However, developing a prudent and viable methodology to fabricate high-quality semiconductor nanocrystals exhibiting tunable luminescence, including single-component white light emission, is challenging. Herein, we report a facile one-pot synthetic route to fabricate white light emitting CdSe x S y nanocrystals demonstrating high quantum yield using CdO, S powder, and Se powder as precursors. A 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 Se/S molar ratio. The pristine CdSe x S y nanocrystals exhibited a broad visible range emission from 400 to 750 nm. The CdSe x S y nanocrystals (Se/S = 0.4) displayed white light emission with Commission Internationale de l’Eclairage (CIE) chromaticity coordinates of (0.30, 0.31) and quantum yield of 50 ± 3%. Moreover, by manipulating the Se/S ratio effectively, the band-edge (∼400–450 nm) to trap-state (∼550–750 nm) emission was tuned, and the distinct shades of white light were obtained. The white light emission was retained in nanocrystals-embedded poly­(methyl methacrylate) (PMMA) thin film and also in the hydrogel matrix. Furthermore, white light emission characteristics from CdSe x S y nanocrystals (Se/S = 0.4), PMMA thin film, and thin film coated white light emitting devices were found to be similar even after months of fabrication, indicating the high stability of the nanocrystals and sustainability of the materials derived from nanocrystals. The one-pot, low-cost fabrication route demonstrated in the present study offers the promising scope of white light emitting CdSe x S y nanocrystals in solid-state display applications.