Title Realization of deep-blue TADF in sterically controlled naphthyridines for vacuum- and solution-processed OLEDs /
Authors Kreiza, Gediminas ; Banevičius, Dovydas ; Jovaišaitė, Justina ; Juršėnas, Saulius Antanas ; Javorskis, Tomas ; Vaitkevičius, Vytenis ; Orentas, Edvinas ; Kazlauskas, Karolis
DOI 10.1039/d0tc01637c
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Is Part of Journal of materials chemistry C.. Cambridge : Royal Society of Chemistry. 2020, vol. 8, p. 8560-8566.. ISSN 2050-7526. eISSN 2050-7534
Keywords [eng] OLED ; deep-blue ; TADF emitter ; carbazole–naphthyridine ; H-bonding ; sterically controlled charge-transfer ; EQE ; electroluminescence
Abstract [eng] Narrow-band deep-blue (emission peak < 460 nm) TADF emitters are in demand for commercial OLED display applications, yet the development of efficient emitters with low efficiency roll-off is very challenging. To address this issue, herein, we studied carbazole–naphthyridine (donor–acceptor)-based blue-emitting TADF compounds, which were designed by using both the H-bonding and sterically controlled charge-transfer (CT) interactions between D and A units. Methyl substitution employed at the first position of t-butyl-carbazole donors was found to affect CT strength and consequently the TADF properties of the studied compounds, enabling a significant reduction of delayed fluorescence lifetime (down to 3.1 μs) and enhancement of reverse intersystem crossing rate (up to 106 s−1). The naphthyridines were demonstrated to hold great potential as deep-blue TADF emitters suitable for both vacuum- and solution-processed TADF OLEDs. The optimized devices with 7 wt% naphthyridine emitter in a weakly polar mCP host delivered external quantum efficiencies (EQEs) of up to ∼17.6% and ∼13.5% for vacuum- and solution-processed OLEDs, respectively. Unsubstituted naphthyridine exhibited deep-blue (λmax < 460 nm) and narrow-band (FWHM = 66 nm) electroluminescence, whereas the more twisted methyl-substituted compound expressed broader band (FWHM > 80 nm) sky-blue (λmax ≈ 480 nm) emission. The demonstrated emitters are among the best-performing conventional D–A-type blue/deep-blue TADF emitters in terms of EQE and efficiency roll-off properties of their devices.
Published Cambridge : Royal Society of Chemistry
Type Journal article
Language English
Publication date 2020