Hydrothermal synthesis of ultrasmall CuCrO2 nanocrystal alternatives to NiO nanoparticles in efficient p-type dye-sensitized solar cells

In this study, we present a facile hydrothermal synthesis of ultrasmall delafossite CuCrO2 nanocrystals, with a typical size of 15 nm × 5 nm, and a high surface area of 87.86 m2 g−1, thermally stable up to 400 °C. The screen-printed CuCrO2 films sintered at different temperatures and under different atmospheres present different optical transmittances, tunable BET surface areas, dye adsorbing amounts, and tunable hole transport rates and hole recombination kinetics, which allows the optimization of the performance of p-type dye sensitized solar cells (DSSCs) based on CuCrO2 photocathodes. At optimized conditions, an open circuit voltage of 102 mV, a short circuit density of 0.491 mA cm−2, a fill factor of 0.398 and an overall photoconversion efficiency of 0.0194% were finally achieved for a coumarin 343 dye sensitized CuCrO2 solar cell. This record is acceptably high in comparison to a DSSC based on an NiO photocathode prepared and tested in similar experimental conditions. The light harvesting properties, charge collection capability, and flat-band potential of CuCrO2 photocathodes and the NiO photocathode have been critically compared.