Incorporating CsPbBr₃ Nanocrystals into Porous AlO(OH) Matrices to Improve their Stability in Backlit Displays

Currently, the poor stability of inorganic perovskite CsPbX₃ (X=Cl, Br, I) nanocrystals restricts their practical application in optoelectronic devices. Therefore, improving the stability of this material remains an urgent task for most researchers. In this study, incorporation of CsPbBr₃ nanocrystals into porous AlO(OH) matrices through simple in situ synthesis was demonstrated to be an efficient approach for improving the nanocrystal stability. X-ray diffraction (XRD) revealed that the as-obtained product was composed of cubic CsPbBr₃ nanocrystals and orthorhombic AlO(OH) compounds. In addition, transmission electron microscopy (TEM) revealed that the CsPbBr₃ nanocrystals were successfully encapsulated by AlO(OH) matrices. The Brunauer-Emmett-Teller (BET) specific surface area was 234.96m² g-1 for AlO(OH) and 60.08m² g-1 for the CsPbBr₃@AlO(OH) composites. The decrease in surface area could be attributed to the filling of the AlO(OH) pores by the CsPbBr₃ nanocrystals. Further, the as-prepared composites showed red-shifted emission at 522nm and a larger full width at half-maximum (FWHM) as 26nm, compared with those of the CsPbBr₃ nanocrystals with the emission at 517nm and FWHM as 17nm. More importantly, the emission intensity preserved 67% of the original value after a storage time of 120h, but bare CsPbBr₃ nanocrystals rapidly degraded within only 1h in the polar ethanol solution. Finally, a light-emitting diode (LED) device was fabricated by coating the CsPbBr₃@AlO(OH) composites and red commercial K₂SiF₆:Mn4+ phosphors on the surface of a blue InGaN chip, covering 96% of National Television Standards Committee. The results indicate that the obtained composites could be promising luminescent materials for backlit displays.