Incorporating Zn2SnO4 Quantum Dots and Aggregates for Enhanced Performance in Dye-Sensitized ZnO Solar Cells

The performance of dye-sensitized ZnO solar cells was improved by a facile surface-treatment approach through chemical-bath deposition. After the surface treatment, the quantum dots of Zn2SnO4 were deposited onto ZnO nanoparticles accompanied by the aggregations of Zn2SnO4 nanoparticles. The ZnO film displayed a better resistance to acidic dye solution on account of the deposited Zn2SnO4 nanoparticles. Meanwhile, the open-circuit photovoltage was greatly enhanced, which can be ascribed to the increased conduction-band edge of ZnO and inhibited interfacial charge recombination. Although the deposition of Zn2SnO4 decreased the adsorption amounts of N719 dye, the aggregates of Zn2SnO4 with a size of 350450 nm acted as the effective light-scattering layer, thereby resulting in an improved short-circuit photocurrent. By co-sensitizing 10 mu m-thick ZnO film with N719 and D131 dyes, a top efficiency of 4.38?% was achieved under the illumination of one sun (AM 1.5, 100 mW?cm-2).