title: Enhanced Photocurrents with ZnS Passivated Cu(In,Ga)(Se,S)2Photocathodes Synthesized Using a Nonvacuum Process for Solar Water Splitting.
abstract: Chalcopyrite Cu(In,Ga)(Se,S)2(CIGS) semiconductors are potential candidates for use in photoelectrochemical (PEC) hydrogen generation due to their excellent optical absorption properties and high conduction band edge position. In the present research, CIGS thin film was successfully prepared on a transparent substrate (F:SnO2glass) using a solution-based process and applied for a photocathode in solar water splitting, which shows control of the surface state associated with sulfurization/selenization process significantly influences on the PEC activity. A ZnS passivation surface layer was introduced, which effectively suppresses charge recombination by surface states of CIGS. The CIGS/ZnS/Pt photocathode exhibited highly enhanced PEC activity (∼24 mA·cm-2at -0.3 V vs RHE). The performances of our CIGS photocathode on the transparent substrate were also characterized under front/back light illumination, and the incident photon to current conversion efficiency (IPCE) drastically changed depending on the illumination directions showing decreased IPCE especially under UV region with back illumination. The slow minority carrier (electron) transportation is suggested as a limiting factor for the PEC activity of the CIGS photocathode.
authors.affiliation: Clean Energy Research Center, Korea Institute of Science and Technology , Seoul 02792, Republic of Korea.|Department of Chemistry, College of Science, Korea University , Seoul 02841, Republic of Korea.
authors.forename: Sang Youn
authors.initials: SY
authors.lastname: Chae
authors.affiliation: Clean Energy Research Center, Korea Institute of Science and Technology , Seoul 02792, Republic of Korea.|Department of Materials Science and Engineering, Korea University , Seoul, 02841, Republic of Korea.
authors.forename: Se Jin
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Clean Energy Research Center, Korea Institute of Science and Technology , Seoul 02792, Republic of Korea.|Department of Physics, College of Science, Korea University , Seoul 02841, Republic of Korea.
authors.forename: Sung Gyu
authors.initials: SG
authors.lastname: Han
authors.affiliation: Clean Energy Research Center, Korea Institute of Science and Technology , Seoul 02792, Republic of Korea.|Korea University of Science and Technology , Daejeon 34113, Republic of Korea.
authors.forename: Hyejin
authors.initials: H
authors.lastname: Jung
authors.affiliation: Applied Optics & Energy R&D Group, Seonam Regional Division, Korea Institute of Industrial Technology , Gwangju 61012, Republic of Korea.
authors.forename: Chae-Woong
authors.initials: CW
authors.lastname: Kim
authors.affiliation: Applied Optics & Energy R&D Group, Seonam Regional Division, Korea Institute of Industrial Technology , Gwangju 61012, Republic of Korea.
authors.forename: Chaehwan
authors.initials: C
authors.lastname: Jeong
authors.affiliation: Clean Energy Research Center, Korea Institute of Science and Technology , Seoul 02792, Republic of Korea.
authors.forename: Oh-Shim
authors.initials: OS
authors.lastname: Joo
authors.affiliation: Clean Energy Research Center, Korea Institute of Science and Technology , Seoul 02792, Republic of Korea.|Korea University of Science and Technology , Daejeon 34113, Republic of Korea.|Green School, Korea University , 145, Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
authors.forename: Byoung Koun
authors.initials: BK
authors.lastname: Min
authors.affiliation: Clean Energy Research Center, Korea Institute of Science and Technology , Seoul 02792, Republic of Korea.|Korea University of Science and Technology , Daejeon 34113, Republic of Korea.
authors.forename: Yun Jeong
authors.initials: YJ
authors.lastname: Hwang