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Triplet excitons in a high-lying reverse intersystem crossing (hRISC) process play an important role in realizing efficient deep-blue materials, and how to make full use of triplet excitons becomes a big challenge. Herein, three anthracene-based deep blue emitters were successfully synthesized, namely DCAT, DCAO and CNAT. Combined experimental tests and theoretical calculations reveal that all three molecules show multi-channel utilization of triplet excitons. Especially for DCAT, the large T1–T2 and small S1–T2 energy gaps, as well as the degenerate state of T2–T6, provide a fast and convenient channel for more triple exciton transitions from T2 → S1. Other conversion channels include T10 → S2 and T10 → S3, and multiple conversion channels together contribute to the high exciton utilization efficiency of DCAT of up to 60%. More importantly, by connecting large steric hindrance groups at the 9 and 10-positions of anthracene, π–π stacking was suppressed and deep-blue emission was achieved. As a result, deep-blue OLEDs based on DCAT exhibit an excellent maximum external quantum efficiency (EQEmax) of 6.8% with the Commission international de I'Eclairage (CIE) coordinates of (0.14, 0.07). These results fully demonstrate the importance of triplet excitons utilized through multi-channel pathways and provide insights into the development of high-performance deep-blue OLEDs. [ABSTRACT FROM AUTHOR]

Although great advances have been achieved in organic electroluminescence fields, highly efficient true blue organic electroluminescence with small CIE coordinates and satisfactory color purity are still limited. Here, we practise a simple and effective molecular avenue for true blue organic electroluminescence, and the strategy is to use biphenyl-bridging hybrids of 1,2,4-triazoles (acceptors) and various donors (D) as the emitters. The as-prepared D–π–A hybrid (TPATZ) containing 2,3,4-triphenyl-1,2,4-triazole and triphenylamine emits bright blue light both in solution and in the solid state, and the non-doped device with TPATZ as an emitter exhibits true blue electroluminescence (EL) with the emission peak at 430 nm and the Commission Internationale de L’Eclairage coordinates of (0.155, 0.047). Moreover, the satisfactory EL color purity with the full width at half maximum (FWHM) of only 50 nm and the maximum external quantum efficiency of 5.92% is obtained, which is among the best true blue OLEDs reported to date. These impressive EL properties are experimentally and theoretically analyzed and emphasize that this simple D–π–A hybrid mode is an effective molecular strategy for highly efficient true blue EL emitters. [ABSTRACT FROM AUTHOR]

In this work, we have synthesized a tetradonor-capped anthracene-centered cruciform 2,6,9,10-tetra(p-dibutylaminostyryl)anthracene (TDC) and its optical properties are investigated. TDC is a light- and heat-stable dye and shows aggregation-enhanced emission (AEE), large and enhanced two-photon absorption cross sections (δ), fluorescence sensing selectively to transition metal ions such as Zn2+ and Cu2+, and appreciable piezofluorochromism (PFC), which is rarely found to exist simultaneously in cruciform or other configuration dyes. The AEE and PFC behaviours result from the existence of a strongly twisted 9,10-branch, and the large and enhanced δ is ascribed to the multiple conjugation pathways and introduction of donor end-groups. TDC possesses a non-centrosymmetric structure and a semi-disjoint Frontier molecular orbital, which could rationalize its fluorescence sensing selectively to Zn2+ and Cu2+. These findings indicate further that an anthracene ring is indeed a unique π-center that is different from other π-centers and can construct novel cruciforms with interesting optical properties. [ABSTRACT FROM AUTHOR]