Photophysics of Deep Blue Acridane- and Benzonitrile-Based Emitter Employing Thermally Activated Delayed Fluorescence

TL;DR

This paper reports the design, synthesis, and characterization of a new blue-emitting OLED material, SBABz4, demonstrating efficient thermally-activated delayed fluorescence and a maximum external quantum efficiency of 7.1%.

Contribution

Introduction of a novel dual acceptor-donor-acceptor structure for pure-blue OLED emission with enhanced TADF properties.

Findings

Achieved pure-blue emission with TADF in SBABz4.

Demonstrated maximum external quantum efficiency of 7.1%.

Confirmed TADF through temperature-dependent TRPL and oxygen-quenching experiments.

Abstract

We designed and synthesized a new organic light-emitting diode (OLED) emitter, SBABz4, containing spiro-biacridine donor (D) in the core surrounded by two benzonitrile acceptors (A). The dual A-DxD-A structure is shown to provide pure-blue emission in relation to its single A-D counterpart. Time-resolved photoluminescence (TRPL) recorded in the broad dynamic range from solutions and solid films revealed three emission components: prompt fluorescence, phosphorescence, and efficient thermally-activated delayed fluorescence (TADF). The latter is independently proven by temperature-dependent TRPL and oxygen-quenching PL experiment. From the PL lifetimes and quantum yield, we estimated maximum external quantum efficiency of 7.1% in SBABz4-based OLEDs, and demonstrated 6.8% in a working device.