High-efficiency and low efficiency roll-off near-infrared fluorescent OLEDs through triplet fusion

作者：Xue, Jie; Li, Chen; Xin, Lijun; Duan, Lian^*; Qiao, Juan^*

来源：Chemical Science, 2016, 7(4): 2888-2895.

DOI：10.1039/c5sc04685h

• LIGHT-EMITTING-DIODES
• BINUCLEAR GALLIUM COMPLEX
• DELAYED-FLUORESCENCE
• CHARGE-TRANSFER
• POLYMER
• DEVICES
• RED
• ELECTROLUMINESCENCE
• ELECTROPHOSPHORESCENCE
• CHROMOPHORES

Though urgently needed, high-performance near-infrared organic light-emitting diodes (NIR-OLEDs) are still rare. NIR-OLEDs based on conventional NIR fluorescent materials usually suffer from low external quantum efficiencies (EQEs) because of the intrinsic obstacles according to the spin-statistics limit and energy-gap law. Herein, we realized high-efficiency and low efficiency roll-off fluorescent NIR-OLEDs through efficient triplet fusion of a bipolar host doped with a special naphthoselenadiazole emitter (4,9-bis(4-(2,2-diphenylvinyl) phenyl)-naphtho[2,3-c][1,2,5] selenadiazole, NSeD). Unlike typical NIR organic donor-acceptor (D-A) chromophores, NSeD features a non-D-A structure and a very large HOMO/LUMO overlap and displays a strong deep-red to NIR fluorescence and unique ambipolar character. The corresponding photoluminescence quantum efficiency of NSeD reaches 52% in solution and retains 17% in the blend film. The optimized NIR-OLEDs demonstrated a strong emission at 700 nm, a high maximum EQE of 2.1% (vs. the predicted theoretical maximum efficiency of 1.3%) and the EQE remained at around 2% over a wide range of current densities from 18 to 200 mA cm(-2), which is amongst the highest performance for NIR-OLEDs based on organic fluorescent materials.

• 出版日期2016
• 单位清华大学