Efficient Solution-Processed Narrowband Green-Emitting Organic Light Emitting Diodes Sensitized by Thermally Activated Delayed Fluorescence Polymer

Abstract

Multiple resonance thermally activated delayed fluorescence (MR-TADF) emitters have been widely used for highly efficient and ultrapure organic light-emitting diodes (OLEDs) via a thermal deposition, while the low-cost solution procedure still remains underexplored. Herein, we propose a TADF polymer as the sensitizer of a narrowband emitter to fabricate solution-processed MR-TADF OLEDs. Due to the effective harvesting of triplet excitons, the sensitized devices based on TADF polymer achieve a narrowband electroluminescence, revealing a maximum external quantum efficiency (EQEmax) of 15.7% together with CIE coordinates of (0.28, 0.65). The performance is approximately 2 times higher than that of non-sensitized devices (7.0%), highlighting the great potential of TADF polymers in efficient solution-processed MR-TADF OLEDs.