文摘
p-Type dye solar cells (p-DSSCs) have been receiving much attention due to their potential role in the elaboration of future tandem dye solar cells with a photoanode and a photocathode built upon n-type and a p-type semiconductors, respectively. So far, NiO appears as the most widely used semiconductor in p-DSSCs. Yet this material suffers from several drawbacks, e.g., a low electrical conductivity and a low redox potential that limit the photovoltaic performances. In that framework, delafossite compounds may be regarded as appropriate substitutes of nickel oxide in relation to their intrinsic optoelectronic properties. Here we report on the nanostructuration of CuGaO2 and its Mg doped derivatives via hydrothermal conditions with Pluronic P123 as surfactant. It appears that a low amount of magnesium helps in preparing samples with higher specific surface areas and stimulates enhanced conversion efficiencies. Beyond a given Ga/Mg substitution rate, a new Cu1-x(Ga,Mg)O2 phase is formed that contains a large amount of Cu vacancies and of structural defects. This new phase shows lower photovoltaic performances compared to those for slightly doped derivatives which suggests that Cu vacancies and/or structural defects limit the mean free path of holes within the photocathode.
