Enhanced Linear and Nonlinear Optical Response of Superhalogen (Al7) Doped Graphitic Carbon Nitride (g-C3N4)

Abstract In this study, pure and superhalogen doped g-C3N4 clusters are computed with the CAM-B3LYP method of DFT to investigate the electronic and optical properties. Single Al7@g-C3N4 and double doped 2Al7@g-C3N4 systems are investigated. The doping of the superhalogen cluster on g-C3N4 especially in a single doped system significantly improves the charge transfer properties by reducing the band gap energies from 6.42 eV to 3.23 eV. The average and total first hyperpolarizabilities (βo and βtotal) remarkably increase from 82 to 3204 au and 136 to 5340 au, whereas average second hyperpolarizability (γo) increases from 14 × 104 to 64 × 104 au due to their lower transition energies. The selected systems were also compared with the external reference molecule p-NA which is a well-known reference molecule for NLO applications. TD-DFT simulations reveal that among pure, single, and double doped systems, the only single doped system shows significantly better outcomes including interaction energies, vertical ionization potential, HOMO-LUMO energies, and UV-Vis absorption. The single doped system shows high absorption in the far-red region that use in lasers. The entitled systems especially single doped systems have the potential to use them as an efficient NLO material.