Enhanced linear and nonlinear optical response of superhalogen (Al7) doped graphitic carbon nitride (g-C3N4)

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 A17@g-C3N4 and double doped 2A17@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 hyper-polarizabilities (beta(0) and beta(total)) remarkably increase from 82 to 3204 au and 136-5340 au, whereas average second hyperpolarizability (gamma(o)) increases from 14 x 10(4) to 64 x 10(4) 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.