PVP/PEG polymer blend based electrolytes for quasi-solid-state dye-sensitized solar cells operating at low temperature

We investigated the performance of quasi-solid-state dye-sensitized solar cells (qs-DSSCs) employing Polyvinylpyrrolidone/Polyethylene glycol (PVP/PEG) blends over a wide temperature range. The photovoltaic performance of qs-DSSCs with conventional polymer electrolytes is very poor at low temperatures, mostly because of the significantly reduced ionic conductivity of the electrolyte. The PVP/PEG blend with a composition ratio of 20/80 exhibited low glass-transition temperature and high ionic conductivity, resulting in a power conversion efficiency (PCE) of 2.91% at a low temperature (−133 °C). This is 2.67 times higher than that of the device PCE (1.09%), with the most efficient and conventional gel-type polymer electrolyte. At ambient temperature, the qs-DSSC with PVP/PEG realized a device PCE of 6.13%, which is comparable to that of cells with conventional liquid electrolyte employing 3-methoxypropionitrile (6.36%) or a polymer electrolyte based on poly (vinylidene fluoride-co-hexafluoropropylene) (6.05%). In addition, the qs-DSSC with PVP/PEG exhibited excellent long-term stability during aging test, retaining approximately 88% of its initial PCE after 1000 h of light irradiation. The electrolyte developed in this study is not constrained by temperature factors and can be applied to solar cells that are viable for practical outdoor use (polar regions and space) with increased power output.