On the Donor: Acceptor Features for Poly(3-hexylthiophene): TiO 2 Quantum Dots Hybrid Materials Obtained via Water Vapor Flow Assisted Sol-Gel Growth.

Here, we present a novel methodology for the preparation of P3HT:TiO 2 quantum dots hybrid materials via water vapor flow-assisted sol-gel growth focusing on the structural, optical and electrical property characterization complemented with first-principles calculations as a promising donor-acceptor system for polymer and hybrid solar cells. X-ray diffraction and UV-Vis spectroscopy analyses suggest that the increasing concentration of TiO 2 quantum dots leads to the formation of higher amounts of amorphous regions while the crystalline regions exhibited interesting aspect ratio modifications for the P3HT polymer. Raman spectra evidenced the formation of charge carriers in the P3HT with increasing TiO 2 quantum dots content and the P3HT:TiO 2 50:50 weight ratio resulted in the best composition for optimizing the bulk electronic conductivity, as evidenced by impedance spectroscopy studies. Our DFT calculations performed for a simplified model of the P3HT:TiO 2 interface revealed that there is an important contribution of the thiophene carbon atoms states in the conduction band at the Fermi level. Finally, our DFT calculations also reveal an evident gain of electron density at the TiO 2 (101) surface while the thiophene rings showed a loss of the electron density, thus confirming that the P3HT:TiO 2 junction acts as a good donor-acceptor system. In our opinion, these results not only present a novel methodology for the preparation of P3HT:TiO 2 quantum dots hybrid materials but also reveal some key aspects to guide the more rational design of polymer and hybrid solar cells.