Enhanced photovoltage (Voc) of nano-structured zinc tin oxide (ZTO) working electrode prepared by a green hydrothermal route for dye-sensitized solar cell (DSSC)

Abstract

Zinc tin oxide (Zn2SnO4, ZTO) nano-structured was prepared by green hydrothermal route for dye-sensitized solar cell. The ZTO was coated on fluorine doped tin oxide glass (fluorine doped tin oxide, FTO glass with surface resistivity of 8–10 Ω/sq) as working electrode by Doctor Blade and spin coating techniques. The ZTO nano-composite was characterized by X-ray diffraction (XRD), fourier transform infrared, field emission scanning electron microscopy, energy dispersive X-ray spectrometry, and UV–Vis diffuse reflectance (DRS) spectroscopy. XRD results of ZTO showed cubic spinel structure of Zn2SnO4. FESEM results showed spherical particles with an average grain size of about 46 nm. The DRS spectra of the ZTO nano-composite showed an optical band gap energy of 3.35 eV, which is relatively lower than that of bare ZnO (3.42 eV). The reduced band gap energy lowered the rate of electron–hole pair recombination and increased the photovoltage (Voc). An enhancement of 60% in photo-voltage (Voc) was observed when nano-composite ZTO was used as working electrode compared to zinc oxide under the illumination of one sun (AM 1.5, 100 mW cm−2). The efficiency of the working electrodes using Zn2SnO4 nano-composite was increased 40% compared to simple zinc oxide. The enhanced photo-voltage (Voc) may be attributed to higher Fermi level of the Zn2SnO4 and reduced band gap. © 2016, Springer Science+Business Media New York.