Creating efficient delayed fluorescence luminogens with acridine-based spiro donors to improve horizontal dipole orientation for high-performance OLEDs

Abstract

Developing high-performance organic light-emitting diodes (OLEDs) with high external quantum efficiency (ηext) and low efficiency roll-off is an unremitting goal, which greatly relies on the exploration of robust luminescent materials. Herein, we report a series of new delayed fluorescence luminogens built with acridine-based spiro donors and benzophenone acceptor. These luminogens have distinct merits of excellent thermal stability, aggregation-enhanced delayed fluorescence, high photoluminescence quantum yields, preferable horizontal dipole orientation and balanced bipolar charge transport. The presence of spiro donors endows the luminogens with large horizontal orientation ratios and thus high light out-coupling efficiencies. The OLEDs based on these luminogens radiate intense green light (504–512 nm) and furnish outstanding ηext values of up to 32.2% and small efficiency roll-offs, which are among the state-of-the-art delayed fluorescence OLEDs with ηexts over 30%, demonstrating their great potentials in the fabrication of highly efficient OLEDs.