Acridan-Grafted Poly(biphenyl germanium) with High Triplet Energy, Low Polarizability, and an External Heavy-Atom Effect for Highly Efficient Sky-Blue TADF Electroluminescence

被引:37
作者
Hung, Miao-Ken [1 ]
Tsai, Kuen-Wei [1 ]
Sharma, Sunil [1 ]
Wu, Jun-Yi [1 ]
Chen, Show-An [1 ]
机构
[1] Natl Tsing Hua Univ, Chem Engn Dept, Hsinchu 30013, Taiwan
关键词
heavy-atom effect; light-emitting diodes; polymers; spin-orbit coupling; thermally activated delayed fluorescence; ACTIVATED DELAYED FLUORESCENCE; LIGHT-EMITTING-DIODES; CONJUGATED POLYMER; HOST; BIPOLAR; PHOTOPHYSICS;
D O I
10.1002/anie.201904433
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
We propose the novel sigma-pi conjugated polymer poly(biphenyl germanium) grafted with two electron-donating acridan moieties on the Ge atom for use as the host material in a polymer light-emitting diode (PLED) with the sky-blue-emitting thermally activated delayed fluorescence (TADF) material DMAC-TRZ as the guest. Its high triplet energy (E-T) of 2.86 eV is significantly higher than those of conventional pi-pi conjugated polymers (E-T=2.65 eV as the limit) and this guest emitter (E-T=2.77 eV). The TADF emitter emits bluer emission than in other host materials owing to the low orientation polarizability of the germanium-based polymer host. The Ge atom also provides an external heavy-atom effect, which increases the rate of reverse intersystem crossing in this TADF guest, so that more triplet excitons are harvested for light emission. The sky-blue TADF electroluminescence with this host/guest pair gave a record-high external quantum efficiency of 24.1 % at maximum and 22.8 % at 500 cd m(-2).
引用
收藏
页码:11317 / 11323
页数:7
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