PPCzTrz, or 9-(5'-(4,6-Diphenyl-1,3,5-triazin-2-yl)-[1,1':3',1''-terphenyl]-2'-yl)-3,6-diphenyl-9H-carbazole in full, is a TADF blue emitter. It has a typical D-π-A type structure consisting of an electron donating 3,6-diphenyl-9H-carbazole, an electron accepting 4,6-dipneyl-triazine, and a phenyl π linker inbetween. With two phenyl groups attached at meta-positions to each of the electron donating, accepting and π linker units, PPCzTrz is nonplanar with increased steric hindrance in structure to effectively weaken intermolecular forces.
By exploring two TADF materials, one distributing and one emitting, a triplet-exciton-distributed (TED) TADF device based on PPCzTrz as the assistant dopant and v-DABNA as the terminal emitter demonstrates:
The TED-TADF mechanism involves singlet excitons being transferred from the host to the emitter via the distributing TADF material by cascade energy transfer, whereas the triplet excitons are transferred to the emitter as singlet excitons by a triplet-exciton recycling process between the low-triplet-energy host and the distributing TADF material.