Room‐Temperature Synthesis of Porous Nanoparticulate TiO₂ Films for Flexible Dye‐Sensitized Solar Cells

Abstract

Abstract A novel room‐temperature method for the preparation of porous TiO 2 films with high performance in dye‐sensitized solar cells (DSSCs) has been developed. In this method a small amount of Ti IV tetraisopropoxide (TTIP) is added to an ethanolic paste of TiO 2 nanoparticles, where it hydrolyzes in situ and connects the TiO 2 particles to form a homogenous and mechanically stable film of up to 10 μm thickness without crack formation. Residual organics originating from the TTIP were removed by UV–ozone treatment of the films, leading to a remarkable improvement of the cell efficiency. Intensity‐modulated photocurrent/voltage spectroscopy (IMPS/IMVS) showed that the main effect of the UV–ozone treatment is to suppress the recombination of photogenerated electrons, thereby extending their lifetime. The efficiency was further increased by preheating the TiO 2 nanoparticles before the paste preparation to remove contaminants originating from the preparation process of the particles. Solar‐to‐electric energy conversion efficiencies of 4.00 and 3.27 % have been achieved for cells with conductive glass and plastic film substrates, respectively, under illumination with AM 1.5 (100 mW cm –2 ) simulated sunlight.