  An ab initio study of the electronic structures of solid
metallotetrabenzoporphyrins (MTBPs) utilized in organic transistors and
photovoltaics is presented. Bandstructures, densities of states, and orbitals
are calculated for H2, Cu, Ni, and Zn core substitutions of the unit cell of
solid TBP, as deposited via soluble precursors that are thermally annealed to
produce polycrystalline, semiconducting thin-films. While the unit cells of the
studied MTBPs are nearly isomorphous, substitution of the core atoms alters the
structure of the bands around the energy bandgap and the composition of the
densities of states. Cu and Ni core substitutions introduce
nearly-dispersionless energy bands near the valence and conduction band edges,
respectively, that form acceptor or deep generation/recombination states.
