Photoelectrochemical cell and energy system using the same

Abstract

A photoelectrochemical cell () includes: a semiconductor electrode () including a substrate (), a first n-type semiconductor layer () disposed on the substrate (), and a second n-type semiconductor layer () and a conductor () disposed apart from each other on the first n-type semiconductor layer (); a counter electrode () connected electrically to the conductor (); an electrolyte () in contact with surfaces of the second n-type semiconductor layer () and the counter electrode (); and a container () accommodating the semiconductor electrode (), the counter electrode () and the electrolyte (). In the semiconductor electrode (), relative to a vacuum level, (I) band edge levels of a conduction band and a valence band in the second n-type semiconductor layer (), respectively, are higher than band edge levels of a conduction band and a valence band in the first n-type semiconductor layer (), (II) a Fermi level of the first n-type semiconductor layer () is higher than a Fermi level of the second n-type semiconductor layer (), and (III) a Fermi level of the conductor () is higher than the Fermi level of the first n-type semiconductor layer (). The photoelectrochemical cell () generates hydrogen by irradiation of the second n-type semiconductor layer () with light.