Photoelectrochemical photovoltaic cells (PEC PVs) consisting of an n-type CdS single-crystal electrode and a Pt black counter electrode in a nonaqueous electrolyte containing an Fe(ClO4)2/Fe(ClO4)3 redox shuttle were studied as a means of obtaining photovoltages above the onset voltage for water splitting with one-step photoexcitation. To improve the photovoltaic performance, the effects of the redox concentration on the cell performance were investigated by UV-vis absorption and PEC measurements and by assessing the electrolyte using hydrodynamic voltammetry. Under visible-light irradiation (420-800 nm) from a Xe lamp, a relatively high open-circuit voltage (VOC) of approximately 1.6 V was obtained, resulting from the negative flat-band potential of the CdS and the positive redox potential of the Fe complexes. Upon optimization of the redox concentration, photocurrent for the Pt/CdS electrode was increased to approximately 30 mA cm-2, and an incident photon-to-current conversion efficiency of up to 80% was achieved at 480 nm as a result of the promotion of the anodic reaction on the Pt surface. Under simulated sunlight, the PEC PV composed of Pt/CdS in a 20 mM Fe(ClO4)2/Fe(ClO4)3 electrolyte exhibited a VOC of 1.38 V, a 3.54 mA cm-2 short-circuit current, and a 2.8% photon-to-energy conversion efficiency.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films