Efficiency improvement for blue triplet-triplet annihilation upconversion organic light-emitting diode

摘要: Recently, a new emission mode, triplet-triplet annihilation up conversion (TTAUC), of OLED was proposed with the mechanism as follows: when carriers recombine at sensitizer layer lower energy bandgap, generated triplet excitons transfer to (TTA) emitter and emit higher photon. In our experiment, we used tris(8-hydroxyquinolinato)aluminum (Alq3) sensitizer, 9,10-Bis(2-naphthyl)anthraces (ADN) TTA 1,1'-(2,5-Dimethyl-1,4-phenylene)dipyrene (DMPPP) diffusion singlet blocking (TDSB) layer. To improve efficiency TTAUC-OLED, 4,4’ -Bis[4-(di-p-tolylamino)styryl]biphenyl (DPAVBi), doped in ADN host. With 6% DPAVBi doping, no obvious change observed electrical characteristics, indicating electron traps from dopant is limited. Maximum EQE achieved EQE= 4.66% optimized device.