[15p-424-1~19] 1.4 Energy conversion, storage, resources and environment

△ [15p-424-3] Evaluation of (ZnSe)_0.85(Cu(In,Ga)Se₂)_0.15 thin film photocathodes for sunlight-driven hydrogen production by using electron-beam-induced current

〇Hiroyuki Kaneko¹, Tsutomu Minegishi^1,2, Kazunari Domen¹ (1.Tokyo Univ,, 2.JST PRESTO)

Keywords:hydrogen, photoelectrode, CIGS

A (ZnSe)_0.85(Cu(In,Ga)Se₂)_0.15 (ZnSe-CIGS) photocathode is a promising candidate as a photocathode material for photoelectrochemical water splitting, because it shows a high onset potential of 0.9 V_RHE. However, the reported photocurrent value was only one fifth of the value estimated from the absorption edge and the sunlight spectrum. In this study, it has been found that the photocurrent of a ZnSe-CIGS is almost doubled when the film is prepared by a novel process, termed as bilayer method here, to form composition gradient of In and Ga in depth. Electron-beam-induced current analysis has suggested that the increase in photocurrent attributes to the formation of uniform built-in potential.