A solid state solar cell using sol–gel processed material and a polymer

We present a heterojunction photovoltaic cell, fabricated from sol–gel TiO2 anatase and poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH–PPV). The solid state cell has a peak power conversion efficiency of 1.6% when illuminated with monochromatic light at 500 nm. At this wavelength the fill factor of the device is 0.67 and the incident photon to current conversion efficiency is 9.5%. The open circuit voltage of the device under these conditions is 0.63 V, similar to the value calculated using capacitance techniques. The anatase TiO2 thin film was prepared by sol–gel processing and dip-coating techniques, whereas the soluble conjugated polymer film, MEH–PPV, was spin coated on top of the TiO2 anatase film. Layer thicknesses of 50 and 80 nm were obtained for TiO2 and MEH–PPV, respectively, and cross section TEM photographs of the TiO2 layer shown the dense nature of the polycrystalline anatase structure with crystallite sizes ranging from 5 to 20 nm.