Issue 22, 2020

Safeguarding long-lived excitons from excimer traps in H-aggregated dye-assemblies

Abstract

The fate of perylene bisimide (PBI) H-aggregates as energy-harvesting materials depends on the ability to circumvent an extremely deleterious but efficient self-trapping process that scavenges the long-lived excitons to form deep excimeric traps. We present the first ever report of an ambient-stable, bright, steady-state photoluminescence (PL) from the long-lived exciton of an H-aggregated PBI crystal. The crystal structure reveals a rotationally displaced H-aggregated arrangement of PBI chromophores, in which transition from the lowest energy exciton state is partially allowed. Polarized absorption spectroscopy on single microcrystals confirms an unusually large exciton splitting of ∼1265 cm−1 that stabilizes the lower exciton state, and inhibits excimer formation. A PL Mueller matrix study shows an increase in the excited state polarization anisotropy, indicating a strong localization of the nascent exciton, which further safeguards it from the self-trapping process. Finally, the possibility of achieving excimer-free excitonic PL in solution self-assembly is also demonstrated.

Graphical abstract: Safeguarding long-lived excitons from excimer traps in H-aggregated dye-assemblies

Supplementary files

Article information

Article type
Edge Article
Submitted
29 Mar 2020
Accepted
14 May 2020
First published
21 May 2020
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2020,11, 5710-5715

Safeguarding long-lived excitons from excimer traps in H-aggregated dye-assemblies

S. Samanta, S. K. Ray, S. Deolka, S. Saha, P. K. R., R. Bhowal, N. Ghosh and D. Chaudhuri, Chem. Sci., 2020, 11, 5710 DOI: 10.1039/D0SC01784A

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