Soluble polyimides were prepared from suitable monomers and were evaluated for their thermal and mechanical properties. The polymers were processed into films for use as supports for transparent, conductive indium tin oxide (ITO) layers. After deposition, annealing in vacuo at temperatures up to 400 degrees C was performed to test the ability of the materials to endure typical device fabrication temperatures without damage to the ITO-coated polymeric substrate. The evolution of the structural, optical, and electrical characteristics with the annealing temperature was analyzed and compared with that of polymeric and conventional glass substrates as references. Polyimide 6F6F, synthesized from hexafluoroisopropylidene diphthalic dianhydride and hexafluoroisopropylidene dianiline, had optimal characteristics for photovoltaic applications, permitting the achievement of conductive, ITO-coated samples with optical transmission greater than 75% in the visible and near-infrared wavelength ranges, without significant deterioration of their properties after vacuum annealing at temperatures up to 350 degrees C. (c) 2006 Wiley Periodicals, Inc.