Triphenylamine-carbazole alternating copolymers bearing thermally activated delayed fluorescent emitting and host pendant groups for solution-processable OLEDs

Thermally activated delayed fluorescent (TADF) polymers are suitable for solution-processed organic light-emitting diodes (OLEDs). However, so far, very few efficient TADF polymers have been reported, which severely limits their commercial application in display and lighting fields. Furthermore, most of the reported TADF polymers are synthesized by the polymerization of low-molecular-weight monomers, which may require complicated modification process or present high steric hindrance resulting in low-molecular-weight polymers. In this work, a series of yellow-green TADF polymeric emitters PTPA-mCP-PxzTrz-X (X = 10, 20, 30, or 40) were designed and synthesized by grafting TADF emitter phenoxazine-triphenyltriazine (PxzTrz) and host unit 1,3-bis(9H-carbazol9-yl)benzene (mCP) onto the pre-obtained triphenylamine-carbazole alternating copolymers. All polymers displayed good solubility and thermal stability. By employing PTPA-mCP-PxzTrz-40 as non-doped emissive layer, the device displayed a maximum luminance of 650.7 cd/m2 and a maximum current efficiency of 3.3 cd/A, which is promising for commercial application.