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. © 2001 Elsevier Science B.V.