Hybrid silicon/P3HT solar cells based on an interfacial modification with a molecular thiophene layer

Hybrid photovoltaic (PV) devices based on a poly(3-hexylthiophene) (P3HT) layer and chemically modified silicon wafers with thiophene groups are reported for the first time. The chemical modification was performed by linking thiophene units directly onto silicon atoms at the n-type silicon wafer surface. To achieve the silicon modification, two-step, chlorination/alkylation reactions were used to convert Si-H into Si-thiophene bonds. Such interfacial modification increased the compatibility and the physical contact between the organic and inorganic phases as well as it promoted a more favorable alignment of band-edge energies. Thus, the hybrid photovoltaic devices based on n-Si/thiophene/P3HT achieved a power conversion efficiency of 8.0% (under simulated air mass 1.5 solar irradiation at 100mWcm(-2)), which was higher than the device containing the silicon wafer with terminal Si-H bonds.