Predictive Simulations for Tuning Electronic and Optical Properties of SubPc Derivatives.

Boron subphthalocyanine chloride is an electron donor material used in small-molecule organic photovoltaics with an unusually large molecular dipole moment. Using first-principles calculations, we investigate how to control the electronic and optical properties of boron subphthalocyanine chloride by substituting the boron and chlorine atoms with other trivalent and halogen atoms and thereby modifying the molecular dipole moment. Gas-phase molecular structures and properties are predicted using hybrid functionals. Using positions and orientations of the known compounds as the starting coordinates for these molecules, stable crystalline structures are derived following a procedure that involves perturbation and accurate total energy minimization. Electronic structure and photonic properties of the predicted crystals are computed using the GW method and the Bethe–Salpeter equation, respectively. Finally, a simple transport model is used to quantitatively demonstrate the effects of the strength and orientation of molecular dipole moments at interfaces on device performance. [ABSTRACT FROM AUTHOR]