Synthesis of Various Sized CuInS 2 Quantum Dots and Their Photovoltaic Properties as Sensitizers for TiO 2 Photoanodes

Understanding the various size effects of CuInS 2 quantum dots is very important for improving the performance of quantum‐dot‐sensitized solar cells. In this work, CuInS 2 quantum dots with sizes ranging from 2 to 8 nm have been synthesized by a simple thermolysis method and a ligand‐exchange process. The quantum dots as sensitizers were uniformly attached to the surface of TiO 2 nanoparticle films capped with 3‐mercaptopropionic acid to form sensitized solar cells. Various sized CuInS 2 quantum dots and sensitized TiO 2 photoanodes were studied by XRD, TEM, UV/Vis, and PL spectroscopy. It was found that the CuInS 2 quantum dots were successfully adsorbed on to the TiO 2 nanoparticle films, and TiO 2 photoanodes sensitized with 3.5 nm CuInS 2 quantum dots have the highest optical absorption and best photovoltaic conversion efficiency of 0.72 % with a short circuit current density of 2.02 mA/cm 2 and a voltage of 0.515 V under AM 1.5 illumination.