3d-transition metals (Cu, Fe, Mn, Ni, V and Zn)-doped pentacene π-conjugated organic molecule for photovoltaic applications: DFT and TD-DFT calculations

Abstract

In this study, we have performed a thorough examination of density functional theory (DFT) and time-dependent (TD) DFT to investigate the structural and optoelectronic properties of 3d-transition metals (Cu, Fe, Mn, Ni, V and Zn)-doped pentacene π-conjugated organic molecule. The HOMO energy level of Ni-doped pentacene is − 6.17 eV wide, i.e., about 1.31 eV greater and more negative than pentacene. The bandgap of the pentacene considerable decreases from 2.20 eV to 1.32, 1.35 and 0.37 eV, for Mn, Zn and V-doped pentacene structures, respectively, which affords an efficient charge transfer from HOMO to LUMO. The HOMO–LUMO energy gap is higher (4.44 eV, for Ni-doped pentacene), implying that the kinetic energy is higher and high chemical reactivity. We have examined, additionally, the reactivity and absorption properties of individual undoped and 3d-transition metals-doped pentacene. Pentacene has the largest vertical ionization potential (6.18 eV), corresponding to the highest chemical stability. Our results suggest that the new 3d-transition metals-doped pentacene may significantly contribute to the efficiency of solar cells.