Cargando…

Multi-resonant thermally activated delayed fluorescence emitters based on tetracoordinate boron-containing PAHs: colour tuning based on the nature of chelates

Multi-resonant thermally activated delayed fluorescence (MR-TADF) materials have attracted considerable attention recently. The molecular design frequently incorporates cycloboration. However, to the best of our knowledge MR-TADF compounds containing nitrogen chelated to boron are still unknown. Rep...

Descripción completa

Detalles Bibliográficos
Autores principales: Meng, Guoyun, Liu, Lijie, He, Zhechang, Hall, David, Wang, Xiang, Peng, Tai, Yin, Xiaodong, Chen, Pangkuan, Beljonne, David, Olivier, Yoann, Zysman-Colman, Eli, Wang, Nan, Wang, Suning
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society of Chemistry 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8827120/
https://www.ncbi.nlm.nih.gov/pubmed/35282615
http://dx.doi.org/10.1039/d1sc05692a
Descripción
Sumario:Multi-resonant thermally activated delayed fluorescence (MR-TADF) materials have attracted considerable attention recently. The molecular design frequently incorporates cycloboration. However, to the best of our knowledge MR-TADF compounds containing nitrogen chelated to boron are still unknown. Reported herein is a new class of tetracoordinate boron-containing MR-TADF emitters bearing C^N^C- and N^N^N-chelating ligands. We demonstrate that the replacement of the B–C covalent bond in the C^N^C-chelating ligand by the B–N covalent bond affords an isomer, which dramatically influences the optoelectronic properties of the molecule. The resulting N^N^N-chelating compounds show bathochromically shifted absorption and emission spectra relative to C^N^C-chelating compounds. The incorporation of a tert-butylcarbazole group at the 4-position of the pyridine significantly enhances both the thermal stability and the reverse intersystem crossing rate, yet has a negligible effect on emission properties. Consequently, high-performance hyperfluorescent organic light-emitting diodes (HF-OLEDs) that utilize these molecules as green and yellow-green emitters show a maximum external quantum efficiency (η(ext)) of 11.5% and 25.1%, and a suppressed efficiency roll-off with an η(ext) of 10.2% and 18.7% at a luminance of 1000 cd m(−2), respectively.