Water-stable all-inorganic CsPb1-XSnXBr2I perovskite quantum dots encapsulated in paraffin for white light-emitting diodes

Abstract

All-inorganic perovskite quantum dots (QDs) have become a hot material in the field of photoelectricity due to their excellent properties, such as high photoluminescence quantum yields (PLQYs), narrow emission wavelengths, and easily controlled PL spectra and particle sizes. However, colloidal perovskite QDs are readily oxidized, degraded in a humid environment, and generated by ion exchange. Here, the CsPb1-XSnXBr2I QDs were synthesized successfully, which the Sn2+ ions partly replacing Pb2+ to reduce the toxicity of Pb-based perovskite. The tunable PL spectrum and band gap from 2.27 to 2.14 eV were obtained by adjusting the Sn content. Meanwhile, we adopted a simple, green and low-cost approach to encapsulated CsPb1-XSnXBr2I QDs within solid paraffin, which not only greatly improved the water stability of QDs, but also maintained outstanding luminous intensity after being immersed in water for 20 days. Finally, the while light-emitting diodes (WLEDs) with varying correlated color temperature (CCT), color rendering index (CRI) and luminous efficiency (LE) based on a combination of blue chip, P–CsPb1-XSnXBr2I QDs and red phosphor were successfully achieved.