Surface Chemistry Matters. How Ligands Influence Excited State Interactions between CsPbBr3 and Methyl Viologen
Jeffrey DuBose a b, Prashant Kamat a b
a Department of Chemistry, University of Notre Dame, United States
b Radiation Laboratory, University of Notre Dame, US, United States
Poster, Jeffrey DuBose, 007
Publication date: 10th June 2020
ePoster: 

The photocatalytic properties of cesium lead bromide (CsPbBr3) perovskite nanocrystals make them attractive for designing light harvesting assemblies. Often ignored, the surface chemistry can dictate the excited state interactions of these semiconductor nanocrystals with charge-shuttling redox molecules. This project explores the impact of CsPbBrnanocrystal surface modification on the excited state interactions with methyl viologen (MV2+) for three different ligand environments: prototypical oleic acid/oleylamine (OA/OAm) ligands, PbSO4-oleate capping, and didodecyldimethylammonium bromide (DDAB) ligands. Native OA/OAm ligands and PbSO4-oleate capping exhibit the strongest complexation with MV2+, whereas the bulky DDAB ligand environment shows an order of magnitude weaker complexation. The electron transfer rate constants as measured from transient absorption spectroscopy vary in the range of 1.2–3.6 × 1011 s–1 for different ligand environments. For DDAB-CsPbBr3 NCs, the efficiency of electron transfer (Φet) is 73%. Despite a protective capping layer, PbSO4-oleate capped CsPbBr3 maintains a redox-active surface which is viable for photocatalytic applications. These results highlight the impact of surface chemistry on excited state interactions of CsPbBr3 NCs and photocatalytic applications.

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