Suppression of photocorrosion in CdS/CdSe quantum dot-sensitized solar cells: Formation of a thin polymer layer on the photoelectrode surface

Suppression of the photocorrosion process is an important subject for quantum dot-sensitized solar cells (QSSCs). A method is reported to suppress the substitution and anodic oxidation reaction in the photocorrosion process of CdS/CdSe QSSCs through the addition of poly(ethyleneoxide) (PEO) to liquid polysulfide electrolyte. In the presence of PEO in the electrolyte, a thin PEO layer is formed on the quantum dot (QDs) film using coordination bonding between the ether group in the PEO and Cd metal ions in the QDs, acting as passivation layer to suppress substitution reaction and anodic oxidation. Due to the passivation effect of PEO thin film, the photostability of QSSCs is significantly improved compared to the liquid polysulfide electrolyte without PEO.