Aggregation-induced delayed fluorescence from phenothiazine-containing donor–acceptor molecules for high-efficiency non-doped organic light-emitting diodes

Abstract

Highly luminescent donor–acceptor molecules based on a phenothiazine donor unit coupled with a xanthone or benzophenone acceptor unit were developed for use in organic light-emitting diodes (OLEDs). While both molecules are almost non-luminescent in pure tetrahydrofuran (THF) solution, a strong yellow delayed fluorescence was observed upon their aggregation in THF/water mixtures or in neat films. This result demonstrates the unique aggregation-induced delayed fluorescence (AIDF) characteristics of these molecules. OLEDs using these AIDF materials as a non-doped emission layer achieved high external electroluminescence quantum efficiencies of up to 11%, which exceeds the theoretical maximum for conventional fluorescent OLEDs. Highly luminescent donor–acceptor molecules based on a phenothiazine donor unit coupled with a xanthone or benzophenone acceptor unit were developed. While both molecules are almost non-luminescent in pure tetrahydrofuran (THF) solution, a strong yellow delayed fluorescence was observed upon their aggregation in THF/water mixtures and in neat films. This result demonstrates the unique aggregation-induced delayed fluorescence (AIDF) characteristics of these molecules. Organic light-emitting diodes (OLEDs) using these AIDF materials as a non-doped emission layer achieved high external electroluminescence quantum efficiencies of up to 11%, which far exceeds the theoretical maximum for conventional fluorescent OLEDs.