Overcoming the Photoinduced Solvent-Assisted Anion Exchange Reactions of CsPbBr3 Perovskite Nanocrystals

• Published in: Journal of physical chemistry. C Vol. 127; no. 29; pp. 14495 - 14501
• Main Authors: Sandeep, Kulangara, Sabrin, Haroon I., Divya, Puthanveedu, Gopika, Kuruppath Y., Fausia, Karayadi H., Shanthil, Madhavan
• Format: Journal Article
• Language: English
• Published: American Chemical Society 27-07-2023
• Subjects: C: Physical Properties of Materials and Interfaces
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.3c02869

Photocatalytic solvent-assisted anion exchange of lead halide perovskites are extremely important, as it can tune the redox properties/band positions of the perovskite nanocrystals. Among that, the generation of chloride ions from the solvents chloroform and dichloromethane by accepting an electron from the photoexcited CsPbBr3 nanocrystals and the resulting anion exchanges are investigated. The redox potentials of the solvent molecules and the band positions of the semiconductor allow for the photoinduced electron transfer process, thermodynamically, in these two solvents. However, the presence of a better electron acceptor N-bromosuccinimide (NBS) can prevent the photocatalytic solvent-assisted chloride ion exchange reactions in CsPbBr3. The preferential interaction of Pb2+ of lead halide perovskites with the bromide ions in preference to Cl–, as a result of Pearson’s hard soft acid base theory, stabilizes CsPbBr3 nanocrystals. This is confirmed by using bromine-containing chloroform as the solvent. Interestingly, in the presence of NBS/bromine, the anion exchange with chloride ions formed by the reduction of solvents can be prevented. The present investigations can give insights into the mechanistic aspects of the anion exchange reaction and suggest new methodologies to stabilize CsPbBr3 nanocrystals in chlorine-containing solvents.