MnS passivation layer for highly efficient ZnO–based quantum dot-sensitized solar cells

Abstract

Interfacial engineering plays a very significant role in suppressing charge recombination and improving the photovoltaic performance in solar cells. The introduction of a buffer or passivation layer is an effective way to modify interfacial behaviours. In this paper, a new approach involving the deposition of a MnS passivation layer was studied to improve the photoelectric conversion efficiency (PCE) of CdS/CdSe quantum dot co-sensitized solar cells (QDSSCs). Compared to the pure CdS/CdSe co-sensitized solar cells, the introduction of the MnS passivation layer can not only modify the surface defects of the quantum dots and suppress charge recombination at the photoelectrode/electrolyte interface, but also enhance the light harvesting capability in terms of both the absorbance intensity and absorption range. This work may provide inspiration for future studies on the interfacial modification of QDSSCs. The best device performance with a ZnO photoanode could be achieved when the MnS passivation layer was deposited for 1 min for each of two successive ionic layer adsorption and reaction (SILAR) cycles. The PCE, open circuit voltage (Voc), short circuit current density (Jsc), and fill factor (FF) were 3.70%, 0.60 V, 13.74 mA cm−2, and 0.44, respectively.