Glucose-Derived Carbon Nanodots in Dye-Sensitized Solar Cells to Increase Efficiency

Although carbon nanodot isolation remains difficult due to the presence of molecular byproducts in a bottom-up synthesis approach using thermal treatment of carbohydrate solutions, their resultant photoluminescence shows promise for down-converting UV photons. In particular, excitation at 390nm results in significant luminescence from 490–540nm, with an excitation wavelength dependence of luminescence (peak absorption occurs at 290nm). Carbonaceous nanodot solutions were derived from high-concentration glucose solutions at 120°C for a 48 hour period and then incorporated into Ruthenium-based dye-sensitized solar cell devices to enhance external quantum efficiency for high energy photons. We found that dialysis combined with solid phase extraction retained photoluminescent properties while allowing for carbon dot isolation in acetonitrile, a soaking solvent for dye-sensitization of TiO₂ nanoparticles, with minimal measurable traces of other chemical byproducts. Successful purification processes, photoluminescence, external quantum efficiency, and J-V curves of these carbon dot-modified devices will be shown to verify this low-cost, earth abundant approach to efficiency enhancement of dye-sensitized solar cells.