Natural-dye-sensitized photoelectrochemical cells for solar energy conversion

Zinc oxide (ZnO) thin films were characterized to determine the band edge potential position for photoelectrochemical water splitting. Zinc oxide films were fabricated on a fluorine-doped tin (IV) oxide (FTO)-coated glass substrate using the sputtering method. Natural dyes were extracted from basil, spinach, pomegranate, thor and sunflower using the aqueous method. A layer of natural dye was deposited on zinc oxide thin film through the drop-casting method and dried at room temperature to make hybrid photoelectrodes to enhance the performance of photoelectrochemical cell (PEC) devices. These hybrid photoelectrodes were characterized using structural, optical and PEC measurements. PECs were tested for generating photocurrent and photovoltage using a three-electrode system in a 0.1 M sodium sulfate (Na₂SO₄) electrolyte. It was found that natural dye plays an important role in enhancing the performance of the hybrid PEC. The dye-sensitized PEC achieved energy conversion efficiency from 0.2 to 0.7% with increment of 15–33% due to the usage of various natural dyes on zinc oxide. Solar energy conversion using these hybrid photoelectrodes may lead to an eco-friendly and cheap way of generating solar fuels in the future.