High performance quasi-solid-state dye-sensitized solar cells based on poly(lactic acid-co-glycolic acid)

A stable quasi-solid-state dye-sensitized solar cell (DSC) with a novel amphiphilic polymer gel electrolyte (APGE) based on poly(lactic acid-co-glycolic acid) (PLGA) is fabricated. The APGE could be readily prepared by a simple method at low temperature of 50 °C and exhibits a quasi-solid property, high conductivity, and long-term stability. The 20 and 40 wt% APGE-based DSCs show high photovoltaic conversion efficiency of 7.5 and 7.4%, respectively, under AM 1.5 simulated sunlight, which is comparable to the liquid electrolyte-based DSC with the efficiency of 7.6%. The 40 wt% APGE-based DSC maintains 95% of the initial performance after 60 days in practical conditions. It is also noteworthy that the APGE endows with higher short-circuit current density than the liquid electrolyte. Different natures of the APGE from the typical polymer gel electrolytes have been elucidated by the I–V measurements, electrochemical impedance spectroscopy, electrophoretic measurements, and transmission electron microscopy.

► A novel polymer gel electrolyte using poly(lactic acid-co-glycolic acid) of proton-donating groups and low crystallinity.
► High conductivity of 10 mS cm−1 at 25 °C.
► Higher short-circuit current density than liquid-based cells (the intercalation of proton).
► High overall efficiencies of 7.5 and 7.4% with high polymer contents of 20 and 40 wt%, respectively (7.6% for the reference liquid-based cell).
► Overall efficiencies lying in ±5% of the initial values during 60 days under ambient conditions.