Efficient and stable cyan-emitting CsPbBr3 quantum dots with zinc bromide inorganic passivation†

The emission of cyan light (470–500 nm), an essential component of the visible light spectrum, plays a crucial role in lighting, display, and light communication. CsPbBr₃ quantum dots (QDs) have shown excellent performance in the green spectral regions, with high color purity, efficiency, and brightness. In order to shift the emission wavelength to the cyan, mixed-halide compositions and quantum-confinement engineering have been employed. Unfortunately, mixed-halide perovskites exhibit undesirable phase separation during optical and electrical excitations, leading to spectral instability. Quantum confinement in pure-halide QDs requires synthetic protocols that involve high loading of long-chain insulating ligands. In this study, we report color-stable cyan CsPbBr₃ quantum dots (C-PQDs) by surface passivation via incorporating Zn²⁺ cations. The incorporation of ZnBr₂ into the precursor solution facilitates Zn²⁺ and Br⁻ substitution into the QDs surface/subsurface layers to induce passivation of existing Pb²⁺ and Br⁻ vacancies and increase the photoluminescence quantum yield from 53.6% to 96.4% at 480 nm. Moreover, after storage under ambient conditions for 30 days or exposure to ultraviolet light for 60 minutes or heating at 333 K, the PL intensity of ZnBr₂-treated C-PQDs only shows a minimal decrease. Furthermore, white and cyan light-emitting diodes (LEDs) are successfully constructed, suggesting that the proposed ZnBr₂-treated strategy can promote the development of perovskite materials for a wider range of optoelectronic applications.