Design of efficient non-doped blue emitters: toward the improvement of charge transport

Charge transport and electronic transition properties of a series of newly designed anthracene-based non-doped blue emitters were investigated by density functional theory calculations. For a highly efficient non-doped device, Cz3PhAn-based emitters were designed to suppress the hole and electron reorganization energies required for structural relaxation with respect to the changes of charged states. As a result, the hole hopping rates of triphenylamine (TPA) and phenylbenzimidazole (PBI) substituted Cz3PhAn derivatives (1, 4, and 5-7) were tremendously enhanced as compared to that of Cz3PhAn due to the suppression of the reorganization energy of holes, λ _h. Moreover, 1 and 4 emitters showed almost identical hopping rates of holes and electrons, which can possibly lead to a perfect charge balance and high efficiency. The photo-physical properties showed that the emission energy of all 1-10 emitters is in 439-473 nm range. It is expected that our rational design strategy can help develop non-doped blue fluorescent emitters for high efficiency.