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Facile color tuning of thermally activated delayed fluorescence by substituted ortho-carbazole-appended triarylboron emitters
摘要： We report the facile tuning of the emission color of thermally-activated delayed fluorescent (TADF) emitters based on an ortho-carbazole-appended triarylboron. A series of ortho-carbazole-appended triarylboron compounds (2-7) are prepared by introducing various electron-accepting substituents, such as phenyl, pyridyl, pyrimidyl, diphenylphosphine oxide, cyano, and dimesitylboryl groups, to the phenylene ring of the dimesitylphenylboryl (PhBMes2) acceptor moiety in the parent ortho-carbazole-appended triarylboron (CzoB, 1). The X-ray crystal structure of the cyano-substituted compound 6 confirms the twisted connectivity between the Cz and phenylene rings. All the compounds exhibit strong TADF (ΦPL = 48-93% in toluene) with large delayed portions. In particular, the emission bands gradually undergo bathochromic shifts from blue (l PL = 463 nm for 1) to greenish yellow (l PL = 532 nm for 7) depending on the electron-accepting substituents. Electrochemical studies show that the greater stabilization of the LUMO level compared to the HOMO is responsible for the red shifts of the emission. Theoretical studies further support the observed bathochromic shifts in the emission, as well as the small energy splittings (D EST) between the excited singlet and triplet states that afford the efficient TADF.
关键词： Ortho donor-acceptor,Color tuning,Triarylboron,Thermally activated delayed fluorescence
更新于2025-11-14 15:28:36
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Impact of intramolecular H bond and n-π* interactions on photophysical and CO2 sensing properties of laterally appended D-π-A triarylboron compounds
摘要： Several examples of laterally appended donor-π-acceptor (D-π-A) boron compounds based on a biphenyl unit have been synthesized and fully characterized. Intramolecular H bonds or n-π* interactions have been found to have a great impact on the photophysical/fluorescent properties of these compounds. Some members of these compounds have been found to display fluorescent response toward CO2.
关键词： Triarylboron,Carbon dioxide sensing,Donor-acceptor compound
更新于2025-09-23 15:19:57
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Triarylboron-based TADF emitters with perfluoro substituents: high-efficiency OLEDs with a power efficiency over 100 lmW <sup>a??1</sup>
摘要： We report boron-based thermally activated delayed fluorescence (TADF) emitters that can lead to high-efficiency organic light-emitting diodes (OLEDs) with high power efficiency and low driving voltage. Ortho-carbazole-appended triarylboron compounds (2–7), in which perfluoroalkyl (CF3 and C3F7) or perfluoroaryl (4-CF3C6F4) groups are attached as secondary acceptors, are prepared and characterized. The compounds exhibit a light greenish to yellow emission in toluene with high photoluminescence quantum yields up to 100%. The twisted donor (D)–acceptor (A) structure, as evidenced by both the X-ray crystal structures and theoretically optimized structures, leads to a small energy splitting (ΔEST < 0.1 eV) between the excited singlet and triplet states, giving rise to strong TADF. High-efficiency TADF-OLEDs are realized with the CF3- and 4-CF3C6F4-substituted compounds as emitters. The optimized OLEDs based on the CF3-substituted emitter (5) show a high external quantum efficiency of 29.9% with a low turn-on voltage of 2.35 V. In particular, the devices achieve an ultrahigh power efficiency (PE) of 123.9 lm W?1 without any light-outcoupling enhancement, which is among the best PE values for the reported TADF-OLEDs. The devices also maintain a high PE at the practical brightness, such as 100 cd m?2 (118.7 lm W?1) and 1,000 cd m?2 (82.3 lm W?1).
关键词： perfluoro substituents,OLED,TADF,high efficiency,Triarylboron
更新于2025-09-19 17:13:59