Theoretical investigation of electronic structure and charge transport property of 9,10-distyrylanthracene (DSA) derivatives with high solid-state luminescent efficiency

The electronic structure and charge transport property of 9,10-distyrylanthracene (DSA) and its derivatives with high solid-state luminescent efficiency were investigated by using density functional theory (DFT). The impact of substituents on the optimized structure, reorganization energy, ionization potential (IP) and electronic affinity (EA), frontier orbitals, crystal packing, transfer integrals and charge mobility were explored based on Marcus theory. It was found that the hole mobility of DSA was 0.21 cm2 V−1 s−1 while the electron mobility was 0.026 cm2 V−1 s−1, which were relatively high due to the low reorganization energies and high transfer integrals. The calculated results showed that the charge transport property of these compounds can be significantly tuned via introducing different substituents to DSA. When one electron-withdrawing group (cyano group) was introduced into DSA, DSA–CN exhibited hole mobility of 0.14 cm2 V−1 s−1 which was on the same order of that of DSA. However, the electron mobility of DSA–CN decreased to 8.14 × 10−4 cm2 V−1 s−1 due to the relatively large reorganization energy and disadvantageous transfer integral. The effect of electron-donating substituents was investigated by introducing methoxy group and tertiary butyl into DSA. DSA–OCH3 and DSA–TBU showed much lower charge mobility than DSA resulting from the steric hindrance of substituents. On the other hand, both of them exhibited balanced transport properties (for DSA–OCH3, the hole and electron mobility was 0.0026 and 0.0027 cm2 V−1 s−1; for DSA–TBU, the hole and electron mobility was 0.045 and 0.012 cm2 V−1 s−1) because of their similar transfer integrals for both hole and electron. DSA and its derivatives were supposed to be one of the most excellent emissive materials for organic electroluminescent applications because of their high charge mobility and high solid-state luminescent efficiency.