Highly efficient and stable CsPbBr3 perovskite quantum dots by encapsulation in dual-shell hollow silica spheres for WLEDs

Abstract

Poor stability of CsPbX₃ (X = Cl, Br or I) perovskite quantum dots (QDs) has greatly hindered their practical photoelectric applications, and how to improve it still remains a critical challenge. Herein, we encapsulated CsPbBr₃ QDs into dual-shell hollow silica (SiO₂) spheres via a simple successive ionic layer adsorption and reaction (SILAR) method. The hierarchical dual-shell structures permit CsPbBr₃ QDs to be anchored on the interior of the SiO₂ spheres while keeping the outside surface undisturbed, which can protect the CsPbBr₃ QDs from direct exposure to the atmosphere. Due to the comprehensive protection of dual-shell hollow SiO₂ spheres, the CsPbBr₃/SiO₂ nanospheres exhibit markedly enhanced stability against light and heat, with a residual PL intensity of 89% after continuous exposure for 72 h to UV light and 65% after 100 °C heat treatment, respectively. In addition, an optimal PLQY of 89% is obtained with suppressed nonradiative recombination. Finally, the fabricated white light-emitting diode (LED) device by employing CsPbBr₃/SiO₂ green phosphors could achieve a wide color gamut covering up to 136% of the NTSC standard. This work provides a novel SiO₂-based encapsulation approach to solve the intrinsic instability issues of CsPbBr₃ QDs, which has a profound impact on their practical applications.