Theoretical study on electron structure and charge transport properties of tetraazapentacene derivatives.

By Means of Marcus electron transfer theory, the charge transport properties of tetraazapentacene (4N-PEN) derivatives were systematically explored. The reorganization energies were studied by both adiabatic potential-energy surfaces and normal mode analysis. The charge diffusion constants were evaluated from the random walk simulation. From the perspective of homology modeling, a selected 4N-PEN derivative without experimental crystal structure was built into three kinds of possible packing modes with reference to its relative analogues and then fully optimized. The calculated results show that the charge transport property for the same kind of systems strongly depends on the packing mode, and the π···stacking is more beneficial for electron transport of 4N-PEN derivatives. Meanwhile, the 4N-PEN derivatives have larger electron transfer integrals and lower energy levels of the lowest unoccupied molecular orbitals as well as smaller electron reorganization energies, which provides a three-in-one advantage for electron transport. Fascinatingly, the data obtained from the hopping and band models both suggest that the 4N-PEN derivatives have the intrinsic property of electron transport. Thus, the 4N-PEN derivatives have the potential for preparing n-type organic semiconductors.