Solution phase synthesis of carbon quantum dots as sensitizers for nanocrystalline TiO2 solar cells

Carbon quantum dots (CQDs) have recently emerged as viable alternatives to traditional semiconductor quantum dots because of their facile and low cost synthesis, long term colloidal stability, and low environmental and biological toxicity. The compatible surface chemistry, good solubility in polar solvents and extensive optical absorption throughout the visible and near-infrared wavelength regions render CQDs as potentially useful sensitizers for photovoltaic applications. Presented herein is a new strategy for the solution phase synthesis of water-soluble, colloidally stable CQDs and a preliminary exploration of their utilization as sensitizers in nanocrystalline TiO2 based solar cells. Under AM 1.5 illumination, the Voc and FF values reach 380 mV and 64% respectively, achieving a power conversion efficiency of 0.13%.