Title： | Tilted Spiro-Type Thermally Activated Delayed Fluorescence Host for ≈100% Exciton Harvesting in Red Phosphorescent Electronics with Ultralow Doping Ratio |
Authors： | Ya-Kun Wang1, Si-Hua Li1, Sheng-Fan Wu1, Chen-Chao Huang1, Sarvendra Kumar1, Zuo-Quan Jiang1*, Man-Keung Fung,1,2 and Liang-Sheng Liao1,2,* |
Institutions： | 1Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Institute of Functional Nano & Soft Materials (FUNSOM) & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University Suzhou 215123, P.R. China 2Institute of Organic Optoelectronics (IOO), JITRI, Wujiang, Suzhou, Jiangsu 215211, P. R. China |
Abstract： | Despite promising efficiency, the high fabrication cost due to the required high concentrations of noble metal based phosphors is still problematic for phosphorescent organic light-emitting diodes (PhOLEDs). This situation becomes even serious considering some practical applications need high luminance, which in turn requires a higher concentration of emitters. A paradigm shift to circumvent these issues can be development of materials that are able to operate efficiently in very low concentrations (<1 wt%). Here, two thermally activated delayed fluorescence hosts (OSTFPCN and OSTFPB) with tilted spiro geometry, small singlet-triplet splitting (ΔEst), and effective resonance energy transfer are developed. Within expectation, record performances with a power efficiency of 63.6 lm W−1 and an external quantum efficiency (EQE) of 31.2% for the red phosphor Ir(MDQ)2(acac) (2.0 wt%) are achieved with OSTFPCN as host. Additionally, a high power efficiency around 58 lm W−1 is also gained even at an ultralow dopant concentration of 0.5 wt% for a OSTFPB based device. Mechanism studies demonstrate that efficiency roll-off can be effectively suppressed in such low concentrations. These findings pave a new way to exploit low cost and high efficiency PhOLEDs. |
IF： | 12.124 |
Link： | http://onlinelibrary.wiley.com/doi/10.1002/adfm.201706228/full.
Editor: Danting Xiang |