Low-Temperature UV Processing of Nanoporous SnO2 Layers for Dye-Sensitized Solar Cells

Connection of SnO2 particles by simple UV irradiation in air yielded cassiterite SnO2 porous films at low temperature. XPS, FTIR, and TGA-MS data revealed that the UV treatment has actually removed most of the organics present in the precursor SnO2 colloid and gave more hydroxylated materials than calcination at high temperature. As electrodes for dye-sensitized solar cells (DSCs), the N3-modified 1-5 mu m thick SnO2 films showed excellent photovoltaic responses with overall power conversion efficiency reaching 2.27% under AM1.5G illumination (100 mW cm(-2)). These performances outperformed those of similar layers calcined at 450 degrees C mostly due to higher V-oc and FF. These findings were rationalized in terms of slower recombination rates for the UV-processed films on the basis of dark current analysis, photovoltage decay, and electrical impedance spectroscopy studies.