RESUMO
High-performance organic light-emitting diodes (OLEDs) that use phosphorescent and/or thermally activated delayed fluorescence emitters are capable of realizing 100 % electron-to-photon conversion. The host materials in these OLEDs play crucial roles in determining OLED performance. Carbazole derivatives are frequently used as host materials, among which 3,3-bis(9H-carbazol-9-yl)biphenyl (mCBP) is often used for lifetime testing in scientific studies. In this study, the π conjugation of the carbazole unit was expanded to enhance OLED lifetime by designing and developing two benzothienocarbazole (BTCz)-based host materials, namely m1BTCBP and m4BTCBP. Among these host materials, m1BTCBP formed a highly efficient [Ir(ppy)3 ]-based OLED with an operational luminescence half-life (LT50 ) of over 300â h at an initial luminance of approximately 12000â cd m-2 (current density: 25â mA cm-2 ). The LT50 value at 1000â cd cm-2 was estimated to be about 23 000â h. This performance is clearly higher than that of mCBP-based OLEDs (LT50 ≈8500â h).
RESUMO
Anthracene derivatives are one of the most promising blue emitters employed in organic light-emitting devices (OLEDs) because of their electrochemical and thermal stabilities. However, their high crystallinity owing to their large π-planar structures severely impedes the progress in the development of solution-based systems. In this work, we developed two types of highly soluble multifunctional anthracene derivatives terminated with ortho-biphenyl and triphenylamine moieties and showed high solubility in general organic solvents such as toluene, tetrahydrofuran, and cyclohexanone at high concentrations (>10â mg mL-1 ), and showed blue emission with a peak wavelength of â¼465â nm and a high photoluminescence quantum yield that ranges up to 81 %. Notably, these emitters are suitable for fabricating both evaporation- and solution-based systems. The evaporation-based system OLED achieved a high external quantum efficiency (EQE) of 5.4 %. While the solution-processed system realized 4.8 %, exhibiting the best performance among the anthracene-based solution-processed OLEDs so far.