Band energy modulation on Cu-doped Sb₂S₃-based photoelectrodes for charge generation and transfer property of quantum dot–sensitized solar cells

Sb₂S₃ quantum dot is prepared as the optical absorber on the ZnO nanorod films to fabricate high-efficiency quantum dot–sensitized solar cells. The band energy of the solar cells is modulated by the different concentration of Cu-doping. Meanwhile, the optical absorption spectra and photoluminescence spectra of different ZnO/Sb₂S₃ photoelectrodes are investigated, which had exhibited the enhancement on optical absorption property and charge separation property by Cu-doping process. The charge transfer properties of the solar cells had also been enhanced by the modulation on band energy structure by different Cu-doping concentration. With the relatively larger optical absorption edge, the 0.3 mM Cu–doped ZnO/Sb₂S₃ quantum dot–sensitized solar cells have exhibited optimal band energy structure for charge transfer, which can obtain higher current density to enhance the photovoltaic power conversion efficiency from 2.55 to 3.14%.