Enhancement of charge photo-generation and transport via an internal network of Sb2Se3/Cu2GeSe3 heterojunctions

Abstract

An interpenetrating iodine-doped-Sb₂Se₃/Cu₂GeSe₃ heterojunction network has been fabricated by controlling the crystallization of a chalcogenide glass. These two crystals absorb strongly and widely the solar spectrum for efficient charge photo-generation, and the heterojunction formed by these two crystals greatly promotes the charge separation. More importantly, these free charge carriers can be efficiently transported through the conductive channels formed by the oriented Cu₂GeSe₃ nanoparticles aggregated between the Sb₂Se₃ rods. The photo-electrochemical measurement shows that this structure results in a photocurrent of 74 μA cm⁻² and a photo-current/dark-current ratio over 12 times at a bias voltage of −0.6 V and under an illumination of 250 W cm⁻². This photocurrent is at least 100 times higher than any of these two crystals individually.