Electrophoretically Achieved Thick and High-Quality NiO Film as Photocathode for High-Performance P1-Based p-DSSCs

This work demonstrates the first preparation of a NiO photocathode by electrophoretic deposition (EPD), with which high-quality and thickness-controllable thick/porous NiO films with a bandgap of about 3.8 eV were obtained. On the other hand, during the preparation of the NiO barrier layer by conventional one-step furnace decomposition of Ni(CH3COO)2·4H2O, an additional step of high-pressure dehydration was introduced, avoiding the dehydration during the furnace reaction and, hence, significantly reducing cracks in the compact NiO film. Under simulated solar irradiation of 100 mW cm–2 and with the as-prepared NiO barrier layer plus the optimal NiO photocathode, the P1 dye based dye-sensitized solar cell (p-DSSC) exhibits a JSC of 3.05 mA cm–2, a VOC of 165 mV, and a power conversion efficiency of 0.16%, which is one of the most efficient p-DSSCs based on the P1 dye. Finally, a preliminary study on a tandem DSSC (t-DSSC) comprising an N719-sensitized TiO2 photoanode and P1-adsorbed NiO photocathode was carried out. A VOC of 700 mV was achieved, which is the sum of those in the two subcells, demonstrating the potential of electrophoretic preparation of NiO in a t-DSSC.