Computational insights into the tailoring of photoelectric properties in graphene quantum dot-Ru(II) polypyridyl nanocomposites

Graphene quantum dot-Ru(II) polypyridyl nanocomposites have emerged as promising materials for photoelectric applications due to their unique optoelectronic properties. This study investigates the impact of pyrenyl, 2,8-di-tert-butylpyreno[4,5-b:9,10-b’]dithiophene, and 2,8-di-tert-butyl-4,10-dihydropyrrolo[3′,2′:9,10]phenanthro[4,5-efg]indole substituents and N^N or C^N analogues of dipyrido[3,2-α:2′,3′-c]phenazine (dppz) on the photophysical characteristics and photoelectric behavior of Ru(II) complexes and their nanocomposites using density functional theory (DFT) calculations. The findings reveal that the incorporation of these substituents and the choice of ligand system significantly influence the chemical reactivity, electron injection, and ground state regeneration processes of the nanocomposites. The C^N nanocomposites demonstrate superior energy conversion efficiencies (14.9–15.6%) compared to the N^N counterparts (1.49–13.4%) due to their higher open-circuit voltages and fill factors. The pyrenyl substituent enhances light absorption and photocurrent generation in the N^N-based nanocomposite but slightly reduces efficiency in the C^N-based nanocomposite. The nanocomposites exhibit improved nonlinear optical characteristics compared to the individual Ru(II) complexes, with the N^N-based nanocomposites showing remarkably higher total hyperpolarizability values. These findings provide valuable insights for designing advanced materials tailored for photoelectric applications by strategically modifying the structural components of GQD-Ru(II) polypyridyl nanocomposites.