Suppressing efficiency roll-off of orange-red thermally activated delayed fluorescence polymer-based OLEDs via copolymerizing co-hosts with cascade energy levels

A series of orange-red TADF polymers incorporating dibenzothiophene, dibenzofuran and carbazole units as co- backbones are successfully synthesized. These polymers demonstrate enhanced photophysical properties, achieving an EQE max of 17.1% in OLEDs.