Incorporation of Plasmonic Silver Coated Gold Nanocubes into Photosystem I Films for Photocurrent Enhancement

Photosystem I proteins have a near unity quantum efficiency and high charge separation. While these are optimal properties of photovoltaic materials, incorporating these proteins with inorganic materials yields low photocurrents in practice. Plasmonic gold nanoparticles are used in a variety of fields for their high absorbance cross-section. Here, silver-coated gold nanocubes are employed for their complimentary absorbance with that of photosystem I. These nanocubes are incorporated into photosystem I films and tested in a three-electrode cell with a mediator solution of 20 mM sodium ascorbate, 1 mM 2,6-dichloroindophenol and 100 mM potassium chloride. A platinum counter electrode and Ag/AgCl reference electrode were used in all photocurrent measurements. Samples were illuminated for 20s by white light from a Leica KL 2500LCD lamp at an approximate light intensity of 140 mW/cm². A 47 nA/cm² enhancement of cathodic photocurrent is demonstrated after incorporation of plasmonic Au@Ag nanocubes.