Sulfone-Based HLCT Molecules with Efficient Orange and White Emission

Abstract

The hybrid local charge transfer (HLCT) state in the molecule opens up new avenues for achieving 100% exciton utilization by transforming high-energy triplet excitons into singlet excitons through reverse intersystem crossing. In this work, we designed and synthesized three D–A type HLCT materials without a π-bridge, PTZ-BTOBF, PXZ-BTOBF, as well as DMAC-BTOBF, using the BTOBF skeleton as the acceptor and phenothiazine (PTZ), phenoxazine (PXZ), and 9,9-dimethyl-9,10-dihydroacridine (DMAC) as donors. The molecules have HLCT excited-state characteristics, allowing for green to orange light emissions and exhibiting moderate PLQY. We fabricated a series of green to orange OLED devices and achieved the highest EQE of 4.99% and the lowest turn-on voltage of 3.05 V. Furthermore, by adjusting the doping concentration, single-emitter WOLEDs have been successfully fabricated and achieved an EQE of 1.82% with CIE coordinates of (0.30, 0.35). The result demonstrates a decent WOLED constructed with an HLCT molecule, which may have potential for practical application.