Surface-State-Mediated Interfacial Hole Transfer Dynamics\nbetween CsPbBr₃ Perovskite Nanocrystals and Phenothiazine\nRedox Couple

Abstract

Recently, cesium lead bromide (CsPbBr₃) perovskite nanocrystals\n(PNCs) gained enormous attention in the designing of photocatalytic\nreactions because of their photocatalytic properties. However, the\nsurface chemistry of nanocrystals is often ignored, which dictates\nthe excited-state interactions of these semiconductor nanocrystals\nwith charge shuttling redox-active molecules. In this work, we have\nexplored the impact of CsPbBr₃ perovskite nanocrystals\nwith three different surface chemistries on the excited-state interactions\nwith the standard hole acceptor phenothiazine molecule. From the steady\nstate photoluminescence and lifetime decay measurements, we have calculated\nthe photoinduced hole transfer (PHT). In the amine-free PNCs case,\nPHT is 6 times higher than for the conventional amine capped ligands.\nUsing the lifetime fast component (τ₁) rate constants,\nwe have calculated the hole transfer constant (<i>k</i>_ht), which is 3.942 × 10⁸ s^–1, and it is 4 times higher in amine-free ligands compared with a\nconventional amine ligand system. These results highlight the impact\nof surface chemistry on the excited-state interactions of CsPbBr₃ PNCs, and we conclude that amine-free PNCs could be an ideal\ncandidate for photocatalytic reactions.