Halogenated perovskite nanomaterials have become a research hotspot because of their extraordinary optical (such as narrow bandwidth emission, adjustable emission band, wide color gamut and high photoluminescence quantum yield) and semiconductor characteristics, and have broad application prospects in photovoltaic, light-emitting diodes, photodetectors and lasers. Perovskite materials have a series of excellent properties, but their poor stability limits their application. Perovskite is an ionic crystal, and its instability mainly comes from the instability of its structure itself and the instability caused by environmental degradation, including temperature stability, light stability and water stability, especially its extremely sensitive property to water, which seriously hinders the application of perovskite materials. This phenomenon has aroused widespread concern, and it is urgent to solve the stability problem of perovskite.

Recently, Xie Yi Research Group of Wuhan University of Technology proposed a method to prepare ligand-free perovskite luminescent materials by water-induced phase transition, and synthesized rod-like CsPb2Br5 embedded Pb(OH)Br materials with excellent stability. Interestingly, after the perovskite sample was soaked in water, it experienced the phase transition from CsPbBr3 and Cs4PbBr6 to CSP B2R5 and the shape transition from nano-plate to micro-rod, thus forming Pb(OH)Br embedded in rod-like CSP B2R5. More interestingly, the PL strength of samples soaked in water not only did not decrease, but greatly increased. Compared with the sample before water treatment, the photoluminescence intensity and photoluminescence quantum yield of the sample after soaking in water are increased by 6 times and 1 1 times respectively, and it has excellent water resistance, high temperature resistance and ultraviolet stability. Related papers were published in ACS applied material & titled "Water-triggered transformation of lead-containing perovskite nanocrystals without ligands-embedding ultra-high stability Pb (OH) br". On the interface.

Paper link:

https://doi . org/ 10. 102 1/ACS ami . 1c 06627

Figure 1 Optical, morphological and phase characterization diagram: (a)PL and absorption spectrum diagram; (b) Fluorescence lifetime diagram; X-ray diffraction pattern; Scanning electron microscope photograph; Transmission electron microscope photograph; (f) High-resolution transmission electron microscope photographs; (g) Photographs of electron diffraction in selected areas.

Fig. 2 Optical, morphological and phase characterization diagram of the sample after long-term immersion.

Fig. 2 Optical, morphological and phase characterization diagrams of stability tests of samples under different harsh environmental conditions: (i) soaking in high-temperature water; (ii) High temperature annealing; (3) ultraviolet irradiation.

Generally speaking, the researchers put forward a simple and environmentally friendly preparation method of perovskite luminescent materials, and the prepared perovskite materials have excellent optical properties and environmental stability. This work provides a new research idea for improving the stability of perovskite.

This article comes from WeChat official account "Materials Science and Engineering". Welcome to reprint, please contact, refuse to reprint to other websites without permission.