▎ 摘　　要

The absorption of the nanocomposites consisting of cir-coronene graphene quantum dot (GQD) and tetraphenylporphyrin (TPP) as a sensitizer of the solar cell is investigated by using the first-principles density functional theory (DFT) and the time-dependent DFT. The structures of the separate GQD, TPP, and their nanocomposites are optimized by hybrid DFT. The energy stability of the obtained structures is confirmed by the frequency analysis. The optical absorptions of the structures are calculated with the time-dependent DFT. The obvious absorption additivity of the nanocomposites is observed. The feasibility of the nanocomposites as the sensitizers of solar cells is examined by the conduction band minimum of TiO2 and the lowest unoccupied molecular orbitals of the nanocomposites. The GQD-3TPPs are identified as the favorable candidate of a sensitizer of solar cell because of the most enhanced in optical absorption, obvious charge spatial separation, suitable LUMO energy levels and the driving force for electron transfer, and the low recombination rate of electron and hole.