Novel tandem structure employing mesh-structured Cu2S counter electrode for enhanced performance of quantum dot-sensitized solar cells

A practical tandem structure with a semitransparent mesh-structured Cu2S counter electrode sandwiched between two TiO2 photoelectrodes has been designed for quantum dot-sensitized solar cells (QDSCs). The mesh-structured Cu2S counter electrode exhibits high catalytic activity for polysulfide electrolyte. CdS/CdSe quantum dot-sensitized TiO2 films have been applied as both top and bottom photoelectrodes to testify the effectiveness of the tandem structure. The influence of the TiO2 film thickness on the performance of the tandem cell has been systematically studied. The optimized tandem QDSC shows an improved photocurrent and 12-percent increase of efficiency over the top cell with a 4.7 μm thick top cell and an 11.0 μm thick bottom cell, presenting a new effective approach towards highly efficient QDSCs.

► This is the first report on practical tandem structures for quantum dot-sensitized solar cells (QDSCs).
► Mesh-structured Cu2S counter electrode exhibits high catalytic activity and good transmittance.
► Influence of photoanode thickness on tandem QDSCs has been systematically studied.
► Tandem QDSCs shows higher photocurrent and efficiency as against the single-photoanode cell.
► This structure can achieve higher efficiency with different QD sensitizers for complementary spectral responses.