Silica-encapsulated MAyCs1−yPbX3 perovskites via one-pot and post-synthetic routes: Tunable bandgap for white emission and photocatalysis

Halide perovskites (HPs) with various dimensional variations have been established as potential materials for fabricating efficient solar light conversion systems, display devices, and thin-film transistors, as well as prominent photocatalysts to trigger solar-driven applications. However, to practically use HPs and focus efforts on their prominent commercialization, degradation mechanisms and strategies for enhancing material stability and device operating durability are being widely studied. In this contribution, an amorphous silica-covered perovskite quantum dot (PQD) structure has been studied to understand (i) the formation mechanism of MAyCs1−yPbX3@SiOx and their halide exchange processes during the synthetic or post-synthetic stage, and (ii) the effect of a non-stoichiometric A-site/X-site ion composition on the photoexcited electron recombination dynamics in the MAyCs1−yPbX3@SiOx PQDs. Through the modification of the ligand-assisted reprecipitation synthetic methods of the conventional CsPbBr3@SiOx to obtain multi-colored MAyCs1−yPbX3@SiOx, the color gamut is comparable to the Rec. 2020 standard—up to 93.55%—with more pristine blue/red emissions. In addition, these PQDs@SiOx can facilitate the photocatalytic (PC) oxidation of benzyl alcohol in ethanol via chemisorption through Si–OH silanol groups, reaching a photodegradation efficiency of ∼35%. This work demonstrates the versatile potential of PQDs to be used in display technologies and to perform PC reactions in polar solvents.