Cubic aggregates of Zn2SnO4 nanoparticles and their application in dye-sensitized solar cells

Zinc Tin Oxide (Zn2SnO4 or ZTO) has emerged as an alternate photoanode material for dye-sensitized solar cells (DSCs), as it offers some advantages as compared to Titania (TiO2). In this work, crystalline ZTO nanoparticles, formed into cubic aggregate structures were synthesised by a solvothermal reaction and employed in photoanodes of DSCs, using either a high extinction coefficient organic (D149) or an organometallic (N719) dye. These were investigated in comparison with devices based on TiO2 photoanodes, with DSCs based on ZTO|D149 showing a promising solar-to-electric conversion efficiency of 4.9%, close to that of TiO2|D149. In addition, experiments were performed using ZTO and TiO2 in aqueous dispersions to degrade Rhodamine B, suggesting ZTO based DSCs should be more stable. Further to this, the low photocurrents seen in ZTO|N719 based devices were investigated, with the dye binding mechanism appearing to significantly impact charge injection efficiency. While the reported PCEs using this material are not as high as for the best TiO2 based devices, the device engineering strategies outlined here provide guidelines for future development of DSCs based on this material.