Issue 23, 2024

A nine-ring fused terrylene diimide exhibits switching between red TADF and near-IR room temperature phosphorescence

Abstract

Herein, we report the first example of a terrylene diimide derivative that switches emission between thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) in the red region. By design, the molecule TDI-cDBT boasts a symmetrical, consecutively fused nine-ring motif with a kite-like structure. The rigid core formed by the annulated dibenzothiophene moiety favoured efficient intersystem crossing and yielded a narrow-band emission with a full-width half maxima (FWHM) of 0.09 eV, along with high colour purity. A small ΔES1–T1 of 0.04 eV facilitated thermally activated delayed fluorescence, enhancing the quantum yield to 88% in the red region. Additionally, it also prefers a direct triplet emission from the aggregated state. The room temperature phosphorescence observed from the aggregates has a longer emission lifetime of 1.8 ms, which is further prolonged to 8 ms at 77 K in the NIR region. Thus, the current strategy is successful in not only reducing ΔES1–T1 to favour TADF but also serves as a novel platform that can switch emission from TADF to RTP depending upon the concentration.

Graphical abstract: A nine-ring fused terrylene diimide exhibits switching between red TADF and near-IR room temperature phosphorescence

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Article information

Article type
Edge Article
Submitted
14 Feb 2024
Accepted
03 May 2024
First published
06 May 2024
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., 2024,15, 8974-8981

A nine-ring fused terrylene diimide exhibits switching between red TADF and near-IR room temperature phosphorescence

S. Jha, K. S. Mehra, M. Dey, S. S, D. Ghosh, P. K. Mondal, M. Polentarutti and J. Sankar, Chem. Sci., 2024, 15, 8974 DOI: 10.1039/D4SC01040J

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