Nanostructured Zinc Stannate as Semiconductor Working Electrodes for Dye-Sensitized Solar Cells
Zn stannate (Zn2SnO4) 27 nm particles were synthesized by hydrothermal treatment. Nano-porous Zn2SnO4 thin films were prepd. on conducting glass substrates and used as working electrodes in dye-sensitized solar cells (DSSCs). Their behavior was compared with std. TiO2 cells, using (TBA)2-cis-Ru(Hdcbpy)2(NCS)2 (N719) dye and an electrolyte contg. 0.7M LiI and 0.05M I2 in 3-methoxypropionitrile. Under the same working conditions, a Zn2SnO4 DSSC showed higher open-circuit potential, but their overall efficiency was lower due to their lower incident photon-to-current conversion efficiency. The behavior of electrons in DSSCs were studied by measuring their transport times and lifetimes by photocurrent and photovoltage transient measurements, resp. The electron diffusion length is similar in both oxides, demonstrating the use of Zn2SnO4 as an electron collector in DSSCs. However, photoinduced absorption measurements reveal problems in the electron injection from the dye to Zn2SnO4, owing to the higher position of its conduction band, in agreement with the higher OCV measured. Zn stannate can be an interesting mesoporous material for DSSC, provided dyes are used which have a higher position of the LUMO compared to that of N719, as it will permit attaining higher photovoltages without affecting the photocurrent.
Record created on 2015-07-06, modified on 2016-10-01