Highly enhanced photocurrent of novel quantum-dot-co-sensitized PbS–Hg/CdS/Cu:ZnO thin films for photoelectrochemical applications

A novel quantum-dot-co-sensitized PbS–Hg/CdS/Cu:ZnO thin films synthesized by low-cost process. The properties of ZnO are also enhanced by doping and co-doping. It is also compared with quantum-dot co-sensitization. Optical properties, crystal structure, morphology, and photocurrent are characterized by UV–Vis spectroscopy, XRD, SEM, and solar simulator, respectively. The bandgap is interestingly reduced highly to 2.6 eV for Ag co-doped Cu:ZnO. It is unprecedentedly reduced to 2.1 eV and even 1.97 eV for CdS and PbS–Hg QD-sensitized thin films, respectively. An exceptionally enhanced photocurrent of 17.1 mA/cm2 is achieved with PbS–Hg-co-sensitized CdS-sensitized Cu:ZnO thin film. This is an excellent achievement, which highly supports the potential of low-cost solar conversion.