FTO/ITO double-layered transparent conductive oxide for dye-sensitized solar cells

摘要

New transparent conductive oxide (TCO) films, fluorine-doped tin oxide (FTO) films coated on indium–tin oxide (ITO) films, were developed for dye-sensitized solar cells (DSC). These transparent conductive films were prepared by a spray pyrolysis deposition (SPD) method at a substrate temperature of 350 °C in ITO and 400 °C in FTO. For ITO deposition, an ethanol solution of indium(III) chloride, InCl_3·4H_2O, and tin(II) chloride, SnCl_2·2H_2O (Sn/(In+Sn), 5 at.%) was sprayed on a TEMPAX #8330 glass substrate (100×100×1.1 mm~3). After the deposition of ITO, FTO films were consecutively deposited for protecting oxidation of ITO films. FTO deposition was carried out by an ethanol solution of tin(IV) chloride, SnCl_4·5H_2O within the saturated water solution of NH_4F. These films achieved the lowest resistivity of 1.4×10~(-4) cm and the optical transmittance of more than 80% in the visible range of the spectrum. The electrical resistance of these films increased by less than 10% even though exposed to high temperatures of 300–600 °C for 1 h in the air. The DSC composed of the films were fabricated to confirm their availability. The films were of large size, 100×100 mm~2. The DSC were made by conventional method. As a result, energy conversion efficiency of =3.7% was obtained.