Impact of transition metal decoration on the electronic and optical properties of polycyclic aromatic hydrocarbon "naphthalene"- A DFT investigation

The transition metal doping on polycyclic aromatic hydrocarbons (PAHs) like naphthalene (C10H8) significantly changes its electronic as well as optical properties reflecting their potential applications in the field of optoelectronic devices such as light emitting diode, solar cell etc. In this study, we investigated the structural, electronic, and optical properties of pure C10H8 and TM (Cr, Mn, Fe, Co, Ni, and Cu) C10H8 by employing the B3LYP functional using density functional theory (DFT). Our calculation revealing binding energies in between 0.76 and 3.84 eV across the TM series, showing TM interaction with aromatic it-electron cloud. Charge transfer between TM and naphthalene compound is confirmed by Mulliken charge analysis indicating TMs acting as charge donors. Decoration of TM reducing the HOMO-LUMO gap from 4.74 eV for pure C10H8 to 2.90 eV, 2.87 eV, 3.17 eV, 2.88 eV, and 3.52eV for Cr, Mn, Fe, Co, Ni, and Cu respectively. Metal dependent electronic interaction leading to splitting of electronic states has been analyzed using density of states. Vibrational properties also calculated by analyzing IR showing extra peaks due to altered electron density while Raman spectra shoed a red shift. These findings underscore the potential of TM-decorated C10H8 in tunable optoelectronic applications.