Highly Efficient Photoanodic Material: Utilizing Dihydrolipoic Acid‐Functionalized CuInS2 Quantum Dots in Photoelectrochemical Cells

Copper indium sulfide quantum dots (CIS QDs) possess the desired optical properties to act as photoanodic material in photoelectrochemical cells, like a high molar absorption coefficient over the entire visible spectrum and long exciton lifetimes. The already reported procedures that utilize photoanodes based on such nanoparticles, however, exploit harsh conditions or utilize non-scalable, expensive, and low-yield syntheses. Here, the construction of CIS QDs adsorbed onto TiO2/FTO photoanodes (FTO = fluorine-doped tin oxide) with a process aimed at avoiding these issues is proposed. In particular, the employment of dihydrolipoic acid as the ligand allows an easy and cost-effective functionalization. CdS layers are deposited onto the nanoparticles to enhance the photoelectrochemical properties. Full characterization of the steady-state and transient photoelectrochemical properties of the electrodes is performed to gain information on the interfacial dynamics among the different components of the electrode. Maximum IPCEs of the order of 50% and a spectral sensitization extended up to 700 nm are obtained in the optimized conditions.