Diphenylsulphone derivatives for a blue thermally activated delayed fluorescence

Abstract

Novel thermally activated delayed fluorescence (TADF) emitters, including diphenylsulphone (DPS) as an electron acceptor and spiro[acridine-9,9'-fluorene] (ACFL) and spiro[acridine-9,9'-xanthene] (ACXA) as electron donors, were designed, and their electronic and optical properties were investigated theoretically for an OLED. We obtain the energies of the first singlet (S-1) and first triplet (T-1)-excited states of TADF materials by performing density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations on the ground state using a dependence on charge transfer amounts for the optimal Hartree-Fock percentage in the exchange-correlation of TD-DFT. The calculated Delta E (ST) values of ACFL-DPS (0.012 eV) and ACXA-DPS (0.014 eV) were small enough to TADF because of the large dihedral angles between the donor and accepter moieties. We show that ACXA-DPS would have a suitable deep blue TADF OLED emitter among the materials with small Delta E (ST) and the emission wavelength of 2.802 eV (442 nm).