Theoretical Study of the Surface Complex between TiO2 and TCNQ Showing Interfacial Charge-Transfer Transitions.

The surface complex of TiO2 nanoparticles and TCNQ was studied using density functional theory (DFT) calculations. The structure of the surface complex was optimized, showing an IR spectrum analogous to the experimental spectrum. From time-dependent DFT calculations based on this optimized structure, we demonstrated that the interfacial charge-transfer transitions from the HOMO of the surface-bound TCNQ molecule to the unoccupied levels of the TiO2 nanocluster occur in the visible to near-IR region.