견고한 주개와 받개를 탄소-탄소 결합을 한 붕소화합물의 합성과 TADF 특성

Abstract

We report three rigid donor (D)-acceptor (A)-type thermally activated delayed fluorescence (TADF) compounds, CzMeBCO (1), BuCzMeBCO (2), and EtCzMeBCO (3), in which 9-substituted 9H-carbazole (9-RCz) donors are linked with a boron-carbonyl (BCO) hybrid acceptor by a carbon-carbon bond. In toluene solution, all compounds exhibit normal fluorescence in deep blue region (426-429 nm) with high photoluminescence quantum yields (PLQYs) of 77%-94% whereas they exhibit greenish blue to green emissions in PMMA film with distinct delayed fluorescence components. High PLQYs are also retained in their rigid state, showing 60%-85% in PMMA film. However, the PLQY and delayed fluorescence lifetime decrease with the increase of the doping concentration of compounds in the film state. The details of synthesis and photophysical properties of compounds will be discussed with theoretical study. Using the TADF emitters, normal performance TADF-OLEDs with maximum external quantum efficiencies of 14.7% for the skyblue (CzMeBCO) and 14.5% for the skyblue (BuCzMeBCO) are presented.