Improved stability and efficiency of perovskite via a simple solid diffusion method

CsPbBr₃ perovskite quantum dots (QDs) have excellent properties such as high emission quantum yield, adjustable spectrum, and wide color range. They have potential prospects in light-emitting diode (LED) displays and solar cells. However, CsPbBr₃ QDs suffer from a low stability with a high sensitivity to water, heat, and light. Here, for the first time, we report a simple method to improve their stability using a high-temperature solid state diffusion to synthesize highly stable and high-quality CsPbBr₃ QDs in a small pore size LTA zeolite (0.41 nm). First, the mixture of PbBr₂, CsBr and LTA zeolite was heated at 650 °C, and the raw materials PbBr₂ and CsBr were diffused into the LTA zeolite through a small aperture. Then, the CsBr/PbBr₂ in the composite was reassembled into CsPbBr₃ QDs (CsPbBr₃@LTA) at room temperature. The CsPbBr₃@LTA obtained by this synthesis method have a high photoluminescence quantum yield (PLQY ∼66%) and extremely high stability. The PLQY of CsPbBr₃@LTA remained above 66% after being kept in the air for 17 months. The PL intensity of CsPbBr₃@LTA remained 78% of the initial value after being immersed in water for 554 days and the PL intensity changed insignificantly after laser irradiation for 20 days.