Nanoarchitectonics of Metal Atom Cluster-Based Building Blocks Applied to the Engineering of Photoelectrodes for Solar Cells

This study deals with the nanoarchitectonic concept applied to the design of photoelectrodes built on two types of cluster core building blocks, namely, {Re6S8i} and {Re6Se8i}. The effect of the nature of the metal/ligand on photoinduced conductivity properties is thus investigated through an in-depth photoelectrochemical study and it is rationalized by the establishment of an energy diagram using a set of complementary optical (ultraviolet-vis-near infrared), electrochemical and spectroscopic (X-ray photoelectron spectroscopy) characterization techniques. The optical and electronic properties of {Re(6)Q(8)(i)}-based films (Q = S or Se) are drastically dependent on the composition. The sulfide-based photoelectrodes exhibit ambipolar behavior with an n-type domination whereas the selenide-based photoelectrodes have a p-type semiconducting behavior. Such electronic properties can be exalted by increasing the interactions between the cluster building blocks by heating. The design of mixed {Re(6)Q(8)(i)}-based photoelectrodes combining the two n-{Re6S8i} and p-{Re6Se8i} cluster core-based building blocks is explored. The physical properties of the heterostructures can be tuned by controlling the {Re6S8i}:{Re6Se8i} ratio and the interaction between the clusters. The creation of such nanoarchitectonic p-n junctions allows the optimization of the photocurrents generated by increasing the separated charge state lifetime that turns out to be attractive for solar cell applications.