Dual-shell protection enables highly efficient and stable all-inorganic perovskite composites for light-emitting-diodes

Lead-halide perovskite nanocrystals (NCs) present superior photoelectric properties, but the poor stability seriously hinders their practical application. The encapsulation of perovskite NCs inside mesoporous silica (m-SiO 2 ) matrix is considered as one of the most feasible pathways to improve the stability of NCs. However, the challenges of loose encapsulation structure, aggregation of particles, high energy consumption during the preparation of CsPbX 3 @m-SiO 2 composites have not yet been overcome, which throw a shadow over the large-scale commercial applications. Here, we present a dual-shell encapsulation strategy that enables the formation of highly emissive CsPbBr 3 @m-SiO 2 @SiO 2 composites, achieving an exceptional photoluminescence quantum yield (PLQY) of 97.37 %. The reaction parameters for the preparation of composites are meticulous investigated. The CsPbBr 3 NCs can be well formed inside the pores of m-SiO 2 as the m-SiO 2 is introduced into the precursor solution. The secondary SiO 2 shells can effectively seal the open pores of m-SiO 2 . As a result, the as-prepared CsPbBr 3 @m-SiO 2 @SiO 2 composites present excellent stability, in which the composites can maintain 93.16 % of initial intensity after storage for 84 days. Besides, a series of CsPbX 3 @m-SiO 2 @SiO 2 composites with tunable emission wavelength in the range of 428.6–630.6 nm are prepared through facile designing the halide ratios of precursor solution, which present a wide color gamut (148.48 % of the National Television Standards Committee). In addition, a white light-emitting diode (LED) is fabricated by combining CsPbBr 3 @m-SiO 2 @SiO 2 composites and K 2 SiF 6 :Mn 4+ phosphors with a 455 nm LED chip, which exhibits good photoelectric performances. This facile low-temperature dual-shell encapsulation strategy reported here provides a new pathway for preparing high-performance perovskite composites, facilitating their practical photoelectric application.