Undoped highly efficient green and white TADF-OLEDs developed by DMAC-BP: manufacturing available via interface engineering

摘要

We report on the development of green and white OLEDs with high efficiency based on Bis(4-(9,9-dimethylacridin-10(9H)-yl) phenyDmethanone (DMAC-BP) manufactured by a facile vacuum evaporation technique via device interfaces engineering. Single, double, and three organic layer undoped OLEDs based on DMAC-BP have been fabricated. Among the developed green devices, the performance of three-layer structured OLEDs is the optimum when mCP (1,3-Bis(carbazol-9-yl)benzene) works as the hole transport layer (HTL) and electron block layer (EBL). The measured maximum external quantum efficiency (EQE), current efficiency (CE), power efficiency (PE), and luminance are 8.1%, 25.9 cd/ A, 20.3 lm/W, and 42,230 cd/m~2, respectively. Importantly, the OLEDs retain the most of their performance at 1000 cd/m~2, and the EQE, CE, and PE are 7.2%, 23.7 cd/A, and 19.1 lm/W, respectively. The achieved high efficiency is attributed to the bipolar transport characteristics of DMAC-BP and the matched bandgap between HTL and emission layer (EML). In addition, WOLEDs with DMAC-BP as green layer are all warm white devices. Among them, the structure of green-red-blue (device W3) demonstrates the best performance with a maximum EQE and brightness of 4.4% and 7525 cd/m~2. Our findings will facilitate the great potential applications of undoped TADF emitters, and establish a good foundation for the preparation of high-efficiency and low-cost commercial OLEDs.