Kinetics of Triplet Exciton Energy-Transfer Processes in Triplet Sensitizer-Doped Fluorescent Polymers

Triplet sensitization is an important aspect of enhancing the performance of organic light emitting diodes (OLEDs). Triplet-Triplet annihilations (TTA) process is known to increases the efficiency of OLEDs. In this case, the time scale of triplet diffusion is an important parameter. In this paper we have studied triplet energy transfer process as a function of timescale and temperature in pure and phosphorescent molecules FIrpic (Bis[2-(4,6-difluorophenyl) pyridinato-C2,N](picolinato)iridium(III)) doped F8BT (Poly(9,9-dioctylfluorene-alt-benzothiadiazole)) films. We have investigated the dynamics of triplet energy transfer processes by probing the corresponding delayed fluorescence (DF) spectra (of the F8BT host system) generated from TTA. We have noticed that the dynamics of DF depends on the diffusion kinetics of triplet excitonic state. We find that the successful triplet transfer to the host polymer system is directly proportional to the triplet lifetime of the guest molecule. We have further implemen...