Quinoline-Coupled Coumarin-Based Ruthenium(II) Dye Sensitizer for Photoelectrochemical Cells and Solar Cells: A Mimic for an Artificial-Light-Harvesting System

Abstract

The conversion of solar energy into chemical energy by the use of dye-sensitized solar cells (DSSCs) and dye-sensitized photoelectrochemical cells (DSPECs) has been considered a convenient method in recent years. Herein, DSPEC and DSSC devices are fabricated by mimicking the function of photosystem II in natural photosynthesis with a new quinoline-coupled coumarin-based ruthenium(II) dye (RQC)-sensitized TiO2 semiconductor as the light-harvesting center. By using the RQC-sensitized TiO2 as the working electrode, photoelectrochemical water-splitting reactions are effectively conducted in a phosphate buffer solution (pH = 6), with 30 mm triethanolamine as the sacrificial electron donor. Oxygen and hydrogen bubbles are evolved from the working electrode and counter electrode, respectively. By applying +0.78 V potential versus a relative hydrogen electrode, an initial photocurrent density of 11.07 mA cm−2 and a final photocurrent density of 9.66 mA cm−2 are achieved. Under this condition, a maximum photoelectrochemical water splitting efficiency of 4.98% is obtained. The photocurrent–voltage (J–V) characterization of the DSSC device fabricated with RQC under standard AM 1.5G illumination furnishes a Jsc of 11.4 mA cm−2, Voc of 0.69 V, fill factor of 0.53, and power conversion efficiency (η) of 4.16%.