CsPbX/SiO (X = Cl, Br, I) monoliths prepared via a novel sol-gel route starting from CsPbX nanocrystals.

We developed a facile synthesis of nanocomposite powders of CsPbX nanocrystals (NCs) embedded in silica. The synthesis starts from colloidal CsPbX NCs that are mixed with tetraethyl orthosilicate in the presence of nitric acid, which triggers the sol-gel reaction yielding the formation of SiO and the conversion of starting NCs into CsPbX ones. The overall reaction delivers CsPbX NCs encased in a silica matrix. The resulting CsPbX/SiO nano-composite powders exhibited enhanced moisture and thermal stability in air. Also, when mixing different CsPbX/SiO samples having diverse anion compositions, no interparticle anion exchange processes were observed, which is a further indication that the silica matrix acts as a robust barrier surrounding the NCs. Finallly, we used these composites as down-converter phosphors on top of a blue light-emitting diode (LED), delivering nearly ideal white light emission with the Commission Internationale de l'Eclairage (CIE) color coordinates (0.32, 0.33).