Excited State Charge Carrier Dynamics in TiO₂ wrapped Perovskite Cs₂AgBiBr₆ Nanocrystals

The halide double perovskites (DP) have recently emerged as a potential candidate for photocatalysis, LED, and solar cells applications. Here, we report the excited state carrier dynamics of DP Cs₂AgBiBr₆ nanocrystals (NCs) wrapped with amorphous TiO₂ (a-TiO₂). A nanocomposite is formed through the antisolvent recrystallization route by incorporating a-TiO₂ around Cs₂AgBiBr₆ NCs. The optical and electrical properties of DP NC and a-TiO₂ coated DP NC were characterized by UV vis, PL, FTIR, and cyclic voltammograms study. The femtosecond transient absorption spectroscopy reveals that the fastest component of lifetime enhances from 1.6 ps to 2.2 ps after TiO₂ wrapping confirming efficient suppression of defect states in DP NCs. Finally, these heterostructures were successfully used for CO₂ reduction.