科研之友
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摘要
Polycyclic aromatic hydrocarbon (PAH) compounds are prospective materials for highly efficient narrowband organic light-emitting diodes. Specifically, boron-nitrogen doped PAHs exhibit multiple resonance (MR) effect toward thermally activated delayed fluorescence (TADF) and narrow full width at half-maximum (FWHM). Currently, the molecular design strategy for bathochromic-shifted narrowband MR-TADF emitters is a hotspot and challenging puzzle. Herein, a carbonyl is fused in the boron-nitrogen doped PAH for constructing a boron/nitrogen/carbonyl MR-TADF emitter. Benefiting from the carbonyl, the developed emitter exhibits enhanced intramolecular charge transfer and decreased reorganization energy, which displays bathochromic-shifted narrowband emission pertinently. As a consequence, the proof-of-concept compound TCZBAO achieves an emission peak at 522 nm and narrow FWHM of 39 nm, while the carbonyl-free TCZBAC exhibits an emission peak at 502 nm and FWHM of 46 nm. Maximum external quantum efficiencies of 36.1 % and 32.4 % are realized for the devices based on TCZBAO and TCZBAC, respectively, indicating the guiding significance of the proposed design strategy for developing bathochromic-shifted narrowband MR-TADF emitters. @@@ A proof-of-concept polycyclic aromatic hydrocarbon compound named TCZBAO is developed with boron/nitrogen/carbonyl hybridized multiple resonance effect, reinforced short-range charge transfer character, and decreased reorganization energy. Maximum external quantum efficiency of 36.1% is achieved for its OLED device with bathochromic-shifted EL peak at 522 nm, narrow FWHM of 39 nm, and significantly relieved efficiency roll-off.image
