A Solid-Liquid Soggy-Sand Electrolyte for Dye-Sensitized Solar Cells

The electrolyte is one of the crucial components in dye sensitized solar cells (DSSCs), allowing for fast diffusion of charge carriers between the electrodes and directly affecting photocurrent density (JSC), photovoltage (VOC), and fill factor (FF). Quasi-solid state DSSC electrolytes typically ensure mechanical properties of a solid and diffusive property of a liquid, circumventing practical problems such as solvent volatility, leakage, photodegradation and corrosion of counter electrode. In this study, a polyethylene glycol dimethyl ether (PEGDME, Mw = 150 g mol−1) based I−/I3− electrolyte containing mesoporous SiO2 particles (MSU-H, 15 nm pores) is investigated in terms of ionic conduction and DSSC performance. Similarly as in “soggy sand” electrolytes, preferential adsorption of anions is observed by Zeta potential measurements and ionic conductivity of the liquid electrolyte can be enhanced. High values of photovoltaic parameters at 1 sun irradiation (JSC = 11.5 mA cm‒2, VOC = 0.69 V, FF = 0.47, 6.3% efficiency) at 2.8 vol% SiO2 suggests an improved regeneration kinetics of the dye molecules. Transient photocurrent experiments confirmed favorable mass transport. A remarkably high 11.2% efficiency was measured under 0.2 sun irradiation.