CsPbBr₃‐Quantum‐Dots/Polystyrene@Silica Hybrid Microsphere Structures with Significantly Improved Stability for White LEDs

Abstract

Cesium‐lead‐halide perovskite quantum dots (PQDs), which have superior optical and electronic properties, are regarded as excellent materials for various optoelectronic devices. However, their unstable nature greatly hinders their practical application. Herein, a simple hydrolysis encapsulation method is developed to embed PQDs into mesoporous polystyrene microspheres (MPMs) followed by a silica shell covering process, which generates luminescent PQDs/MPMs@SiO2 hybrid microspheres with significantly enhanced stability. The obtained CsPbBr3‐PQDs/MPMs@SiO2 hybrid microspheres show a high photoluminescence quantum yield of 84%. More importantly, the MPMs@silica protective shells effectively cut off direct contact between outer erosive species and the inner embedded PQDs and modify the hybrid microspheres with ultralong alkyl chains for improved resistance to solvents and heat. Hence, these CsPbBr3‐PQDs/MPMs@SiO2 hybrid microspheres exhibit good chemical/physical stabilities, even when exposed to harsh environments, such as deionized water, isopropanol, acid/alkali solution, anion‐exchange reactions, and heating. Particularly, the water stability, which produced the remaining ≈48% proportion of the initial fluorescence intensity after a quite long aqueous storage period of 30 d, is the best reported among the stability‐related studies of PQDs. Meanwhile, white light‐emitting diodes (LEDs) are achieved by mixing green CsPbBr3‐PQDs/MPMs@SiO2 microspheres with red commercial phosphors on a blue chip. High power efficiency of 81 lm W−1 and good electroluminescence stability are obtained.

Water Triggered Synthesis of Highly Stable and Biocompatible 1D Nanowire, 2D Nanoplatelet, and 3D Nanocube CsPbBr3 Perovskites for Multicolor Two-Photon Cell Imaging

“… 30 − 44 In the past few years, there have been enormous efforts to enhance stability of zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) lead halide perovskites by functionalizing them with moisture-tolerant molecules. 34 − 54 …”

Single-Source Thermal Evaporation Growth and the Tuning Surface Passivation Layer Thickness Effect in Enhanced Amplified Spontaneous Emission Properties of CsPb(Br0.5Cl0.5)3 Perovskite Films

“…CsPbX 3 exhibit relatively improved stability compared with those of their organic–inorganic hybrid equivalents (e.g., MAPbX 3 and FAPbX 3 ). However, the low formation energy of crystal lattices coupled with the high delocalization activity of surface ions makes CsPbX 3 highly susceptible to polar solvents and sensitive to moisture and air, anion-exchange reactions, and thermal heating in practical operation [ 7 , 8 , 9 , 10 ]. Such inherent instability significantly impedes the further development and future application of CsPbX 3 in optoelectronics fields.…”

Core/Shell Metal Halide Perovskite Nanocrystals for Optoelectronic Applications

“…(Figure 1). [37][38][39][40] In situ and post-synthesis strategies have been used to achieve these architectures and the majority of these studies adopt an epitaxial growth approach for the core/shell perovskite NC growth. As shown in Figure 1a, Li group synthesized CsPbBr 3 /Cs 4 PbBr 6 core/shell structures by a seeded growth method, in which the pre-synthesized CsPbBr 3 seeds were coated with Cs 4 PbBr 6 in the presence of halide and cesium precursors.…”

“…Wang et al [42] developed a spray-assisted transition process to encapsulate CsPbBr 3 perovskite NCs into poly(methyl methacrylate) (PMMA) polymer nanospheres, forming CsPbBr 3 / PMMA globules suitable for live-cell imaging. In addition, mesoporous polystyrene microspheres (MPMs) were used by Yang et al [39] to load CsPbBr 3 NCs before coating this composite structure with a layer of SiO 2 to produce CsPbBr 3 / MPMs/SiO 2 multi-core/shell structures (Figure 1c). The obtained MPMs have low thermal conductivity, good hydrophobicity, acid and alkaline resistance, and can provide numerous anchor sites for large-volume perovskite NCs loading.…”

“…Reproduced with permission. [39] Copyright 2019, Wiley-VCH. e) Schematic illustration of the synthetic strategy and fabrication of perovskite/SiO 2 .…”