Encapsulation of CsPbBr3Nanocrystals by a Tripodal Amine Markedly Improves Photoluminescence and Stability Concomitantly via Anion Defect Elimination

Pradhan, J and Moitra, P and Umesh, . and Das, B and Mondal, P and Kumar, GS and Ghorai, UK and Acharya, S and Bhattacharya, S (2020) Encapsulation of CsPbBr3Nanocrystals by a Tripodal Amine Markedly Improves Photoluminescence and Stability Concomitantly via Anion Defect Elimination. In: Chemistry of Materials, 32 (17). pp. 7159-7171.

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Abstract

Photoluminescence of halide perovskite nanocrystals (NCs) quenches rapidly due to ambient instability, inherent trap states, and imperfect ligand-NC passivation. We report a novel synthetic strategy to enhance the stability and eliminate trap states of CsPbBr3 NCs simultaneously by in situ introduction of a tripodal tertiary ammonium bromide ion pair ligand tris(2-aminoethyl)ammonium bromide (TREN·4HBr). Tetrabromide ions saturate the PbBr6 octahedra of CsPbBr3 NCs to eliminate the anion vacancies, while TREN with three NH3+ branches enhances efficient encapsulation. TREN·4HBr binds strongly to prevent proton transfer that leads to a facile ligand loss from the NCs surfaces. Ultrafast femtosecond transient absorption kinetics reveals the removal of shallow trap states in the CsPbBr3 NCs leading to a faster carrier recombination to enhance the photoluminescence quantum yield (PLQY). We validate the enhancement in the PLQY by designing light-emitting diodes with an external quantum efficiency of 3.4%. Our work unveils a mechanism for rational improvements of stability and PLQY of CsPbBr3 NCs simultaneously. Copyright © 2020 American Chemical Society.

Item Type:	Journal Article
Publication:	Chemistry of Materials
Publisher:	American Chemical Society
Additional Information:	Copyright to this article belongs to American Chemical Society
Keywords:	Ammonia; Charge carriers; Ions; Lead compounds; Ligands; Perovskite; Photoluminescence; Quantum efficiency; Quantum theory; Stability, Carrier recombination; Defect elimination; External quantum efficiency; Femtosecond transient absorption; Halide perovskites; Nanocrystal (NCs); Photoluminescence quantum yields; Synthetic strategies, Bromine compounds
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	24 Dec 2020 08:27
Last Modified:	24 Dec 2020 08:27
URI:	http://eprints.iisc.ac.in/id/eprint/66985

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