Low-Cost Nanoporous Cu2ZnSnS4 Thin-Film Counter Electrode for Dye-Sensitized Solar Cells

Abstract

The Cu2ZnSnS4 thin film is a well-known and promising electrode material to substitute for the expensive Pt counter electrode used in dye-sensitized solar cells. In this work, we have proposed a novel nanoporous Cu2ZnSnS4 thin film prepared by a simple and non-toxic process for use as the counter-electrode material. The Cu2ZnSnS4 thin film was easily prepared by a simple spin coating process using a sol-gel precursor that consists of metal chlorides and thiourea, followed by thermal annealing. By manipulating the thermal annealing conditions, a Cu2ZnSnS4 thin film with unique nanoporous morphology could be realized, and this film was very effective as the counter electrode owing to its large surface area. Because the size of Cu2ZnSnS4 nanograins was affected by the thermal annealing temperature, the scale of the nanoporous structures of the Cu2ZnSnS4 counter electrode, which significantly affects the photovoltaic characteristics of dye-sensitized solar cells, could be controlled by manipulating the annealing temperature. The structure and morphology of nanoporous Cu2ZnSnS4 thin films were characterized via X-ray diffraction and scanning electron microscopy analysis, and the photovoltaic performance of dye-sensitized solar cells based on the nanoporous Cu2ZnSnS4 counter electrode was also investigated. The nanoporous Cu2ZnSnS4 counter electrode exhibited a power conversion efficiency of 4.494% under 100 mW/cm2 AM 1.5 simulated light, Voc of 0.610 V, Jsc of 10.46 mA/cm2, and FF of 70.44%, and this power conversion efficiency was comparable to that of a conventional Pt counter electrode (5.719%) for the same device configuration. Copyright © 2016 American Scientific Publishers All rights reserved.