201. A red thermally activated delayed fluorescence emitter with mitigated efficiency roll-off via a π-stacked multiple donor–acceptor structure.
- Author
-
Song, Min, Yu, You-Jun, Feng, Zi-Qi, Qu, Zhi-Hao, Zuo, Peng, Yan, Hong-Yan, Jiang, Zuo-Quan, Zhou, Dong-Ying, and Liao, Liang-Sheng
- Abstract
Red to near-infrared organic light-emitting diodes (OLEDs) utilizing thermally activated delayed fluorescence (TADF) emitters continue to exhibit significant external quantum efficiency (EQE) roll-off at high luminance levels exceeding 1000 cd m
−2 , attributed to the relatively modest reverse intersystem crossing rate constant (kRISC ) of approximately 103 –104 s−1 . This study presents a novel TADF molecule, TCPP-DTPA, featuring a structurally rigid π-stacked multiple donor/acceptor design. The enhanced donor/acceptor interactions minimize the energy gap between the singlet and triplet states of the TCPP-DTPA, allowing for an efficient RISC process with a high rate constant of 4.67 × 106 s−1 . The OLED utilizing TCPP-DTPA demonstrates a peak EQE of 23.5% at a wavelength of 618 nm. Additionally, notable EQE values of 7.8% and 14.9% are observed at a luminance of 1000 cd m−2 for OLEDs without and with an energy-transfer assistant dopant in the emissive layer, respectively. This research contributes to enhancing the efficiency of high-brightness red TADF OLEDs, while also offering valuable insights for the optimization of molecular design and device engineering to mitigate the electroluminescence efficiency roll-off. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF