Molecular Design and Synthesis of Dicarbazolophane-Based Centrosymmetric Through-Space Donors for Solution-Processed Thermally Activated Delayed Fluorescence OLEDs
Zhen Zhang, Stefan Diesing, Ettore Crovini, Abhishek Kumar Gupta, Eduard Spuling, Xuemin Gan, Olaf Fuhr, Martin Nieger, Zahid Hassan, Ifor D. W. Samuel, Stefan Bräse, Eli Zysman‐Colman
Abstract
Conjugation-extended carbazolophane donors, dicarbazolophanes (DCzp), were designed and synthesized using a multifold stepwise Pd-catalyzed Buchwald–Hartwig amination/ring cyclization process. Furthermore, elaboration of the DCzp core is possible with the introduction of pendant carbazole derivative groups. This provides a way to tune the optoelectronic properties of the thermally activated delayed fluorescence (TADF) compounds DCzpTRZtBu, dtBuCzDCzpTRZtBu, and dMeOCzDCzpTRZtBu. Solution-processed organic light-emitting diodes (OLEDs) were fabricated and achieved a maximum external quantum efficiency (EQEmax) of 8.2% and an EQE of 7.9% at 100 cd/m2.