Investigations of structural, optical, and photovoltaic properties of Fe-alloyed ZnS quantum dots

Pure ZnS and Fe-alloyed ZnS quantum dots (QDs) prepared by wet-chemical method at room temperature using mercaptoethanol as a capping agent. The nominal concentrations of Fe were 5, 10, and 15% weight of Fe. The QDs were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive analysis of X-rays (EDAX), optical absorption and photoluminescence (PL) measurements. The cubic phase of pure and Fe-alloyed ZnS QDs was indicated using the XRD measurements. It was determined that the sizes of doped samples decrease as the Fe concentrations are increased. The band gaps of QDs were investigated using optical measurements. It was observed that the band gaps and the absorption windows of Fe-alloyed ZnS QDs increase with the increase in the concentrations of Fe. It was seen that as the concentration of Fe increases, both the absorption and the emission peaks of the alloyed ZnS QDs shift to shorter wavelength. The photovoltaic properties of Fe alloyed ZnS QDs have been investigated in this study for the first time. The pure ZnS and Fe-alloyed ZnS QDs were used to make quantum dots-sensitized solar cells. The performances of the solar cells, with the short circuit current density (J_SC) and open circuit voltage (V_OC) and incident photon to electron conversion efficiency (IPCE) of Fe-alloyed ZnS QDs increased with increasing Fe doping. Thus, Fe-alloyed ZnS QDs can be used as promising materials in solar cell technology due to fact that they have wider optical absorption spectrums.