Large-scale synthesis of Cu2SnS3 and Cu1.8S hierarchical microspheres as efficient counter electrode materials for quantum dot sensitized solar cellsElectronic supplementary information (ESI) available: SEM images of ZnO/ZnSe/CdSe nanocables and Nyquist plots of real solar cells containing various counter electrodes and the same photoanode of ZnO/ZnSe/CdSe nanocables. See DOI: 10.1039/c2nr31724a

• Main Authors: Xu, Jun, Yang, Xia, Wong, Tai-Lun, Lee, Chun-Sing
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c2nr31724a

Exploration of new catalytic semiconductors with novel structures as counter electrode materials is a promising approach to improve performances of quantum dot sensitized solar cells (QDSSCs). In this work, nearly mono-disperse tetragonal Cu 2 SnS 3 (CTS) and rhombohedral Cu 1.8 S hierarchical microspheres with nanometer-to-micrometer dimensions have been synthesized respectively via a simple solvothermal approach. These microspheres are also demonstrated as efficient counter electrode materials in solar cells using ZnO/ZnSe/CdSe nanocables as photoanode and polysulfide (S n 2− /S 2− ) solution as electrolyte. While copper sulfide is regarded as one of the most effective counter electrode materials in QDSSCs, we demonstrate the CTS microspheres to show higher electrocatalytic activity for the reduction of polysulfide electrolyte than the Cu 1.8 S microspheres. This contributes to obvious enhancement of photocurrent density ( J SC ) and fill factor (FF). Power conversion efficiency (PCE) is significantly enhanced from 0.25% for the cell using a pure FTO (SnO 2 :F) glass as counter electrode, to 3.65 and 4.06% for the cells using counter electrodes of FTO glasses coated respectively with Cu 1.8 S and CTS microspheres. Hierarchical Cu 2 SnS 3 and Cu 1.8 S microspheres are demonstrated as efficient counter electrode materials for high performance quantum dot sensitized solar cells.