Full-Color Sterically Shielded Boron Difluoride Emitters with Efficient and Ultrapure Electroluminescence via Sensitized Fluorescence
Tianyu Huang, Qi Wang, Renyin Zhou, Hao Chen, Wei Jiang, Jinbei Wei, Guoyun Meng, Guomeng Li, Xuewen Wang, Lian Duan, Dongdong Zhang
Abstract
Emitters with narrowband emissions are essential to improve the color purity of organic light-emitting diodes (OLEDs). Boron difluoride (BF) derivatives have preliminarily exhibited small full width at half-maximum (FWHM) values in electroluminescent devices, which, however, still face formidable challenges in recycling triplet excitons and realizing full-color emissions covering the whole visible spectra. Here, a systematic molecular engineering on the aza-fused aromatic emitting core and peripheral substitutions is made, affording a family of full-color BF emitters spanning from blue (461 nm) to red (635 nm), with high photoluminescence quantum yields of >90% and a small FWHM of 0.12 eV. The device architectures are delicately manipulated to form effective thermally activated sensitizing emissions, first affording the highest maximum external quantum efficiency of >20% for BF-based OLEDs with negligible efficiency roll-off.