Issue 46, 2017

Triplet decay-induced negative temperature dependence of the transient photoluminescence decay of thermally activated delayed fluorescence emitter

Abstract

The photophysical properties of three TX-based D–A isomers (TXO-PhCz1, TXO-PhCz3, and TXO-PhCz4) with a PhCz donor at different substitution positions of phenyl group on a TXO unit were investigated. The substitution position of the PhCz unit significantly impacts the photophysical properties of these isomers. TXO-PhCz1 exhibits a very weak emission in both undoped and doped films, while TXO-PhCz3 and TXO-PhCz4 exhibit a strong emission with the requisite properties for TADF emitters, including a small ΔEST and transient PL decay curves with a prompt and delayed fluorescent component. TXO-PhCz4 exhibits a much stronger orbital coupling than TXO-PhCz3 and then the phosphorescent emission causes the inverse temperature dependence of the transient PL decay, which is contrary to that of TXO-PhCz3 and other TADF emitters. TXO-PhCz4 exhibits a small ΔEST of 23 meV and a short decay time of 14 μs at room temperature, which are much smaller and shorter than those of TXO-PhCz3. Multilayer OLEDs based on TXO-PhCz4 exhibit a very low-efficiency roll-off with a maximum current efficiency of 49.2 cd A−1, a maximum power efficiency of 47.7 lm W−1, and a maximum EQE of 16.3%.

Graphical abstract: Triplet decay-induced negative temperature dependence of the transient photoluminescence decay of thermally activated delayed fluorescence emitter

Supplementary files

Article information

Article type
Paper
Submitted
04 Sept. 2017
Accepted
30 Okt. 2017
First published
31 Okt. 2017

J. Mater. Chem. C, 2017,5, 12077-12084

Triplet decay-induced negative temperature dependence of the transient photoluminescence decay of thermally activated delayed fluorescence emitter

X. Wei, Y. Chen, R. Duan, J. Liu, R. Wang, Y. Liu, Z. Li, Y. Yi, Y. Yamada-Takamura, P. Wang and Y. Wang, J. Mater. Chem. C, 2017, 5, 12077 DOI: 10.1039/C7TC04025C

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