Proposing 3,5-dicyanopyridine motifs for the design of electroactive materials for optoelectronic devices, three electron-transporting semiconductors are synthesised. The best performance was observed for OLED containing FPDD as a host (EQE = 21.9%).
A series of new indolyl-substituted carbazole derivatives were synthesized and their properties were studied. All the final compounds form molecular glasses. They absorb electromagnetic radiation in the range of 200–400 nm and emit in the range of 420–600 nm. The electrochemical properties of the derivatives were found to be determined by the nitro group attached to indole moiety. Relaxation dynamics of transient absorption spectra clearly indicates charge transfer state formation in the solid sample of 5-nitro substituted indolylcarbazole derivative.
A design strategy for efficient MR-TADF emitters needs (i) avoiding aggregation by inducing steric hindrance at peripheral strategic positions, and (ii) combining lateral groups of higher donor character as compared to the central core.
Exciplex-based OLEDs with novel derivatives of trifluorobiphenyl and 3,6-di-tert-butylcarbazole exhibited maximum current, power and external efficiencies of 24.8 mA cm−2, 12.2 lm W−1 and 7.8%, respectively.
Abstract Two phenothiazine‐based electroactive compounds were synthesized by Buchwald‐Hartwig cross‐coupling reaction. The compounds consist of pyridine‐ or benzonitrile accepting moiety and phenothiazine donor fragments linked through tertiary amino linkage. The resulting electroactive compounds showed high thermal stability with 10 % weight loss temperatures of 270 and 308 °C. Both the compounds showed reversible oxidation after repeated scans of cyclic voltammetry. Experimental results in combination with the outcomes of TD‐DFT calculations, were employed to examine the emission nature of the target compounds. By demonstrating the correct choice of acceptor moiety and linking topology, the synthesized compounds were found to be emitters exhibiting efficient RTP. With emission lifetime reaching 26.04 ms and spin‐orbit coupling value of the triplet states with the singlet ground state of 18.72 cm −1 , the radiative recombination of the triplet state is ensured. Having lifetimes of 26 ms and strong sensitivity to oxygen, the benzonitrile‐containing phenothiazine derivative demonstrated fast oxygen response with the quenching constant of 4.97*10 −4 ppm −1 at low oxygen concentrations that is comparable to the corresponding characteristics of reported RTP‐based sensors.
A strategy of fused electron accepting moieties was employed to synthesise a series of donor-substituted quinoxaline–methanone derivatives as red TADF emitters.
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