title: Efficient water-splitting device based on a bismuth vanadate photoanode and thin-film silicon solar cells.
abstract: A hybrid photovoltaic/photoelectrochemical (PV/PEC) water-splitting device with a benchmark solar-to-hydrogen conversion efficiency of 5.2% under simulated air mass (AM) 1.5 illumination is reported. This cell consists of a gradient-doped tungsten-bismuth vanadate (W:BiVO4 ) photoanode and a thin-film silicon solar cell. The improvement with respect to an earlier cell that also used gradient-doped W:BiVO4 has been achieved by simultaneously introducing a textured substrate to enhance light trapping in the BiVO4 photoanode and further optimization of the W gradient doping profile in the photoanode. Various PV cells have been studied in combination with this BiVO4 photoanode, such as an amorphous silicon (a-Si:H) single junction, an a-Si:H/a-Si:H double junction, and an a-Si:H/nanocrystalline silicon (nc-Si:H) micromorph junction. The highest conversion efficiency, which is also the record efficiency for metal oxide based water-splitting devices, is reached for a tandem system consisting of the optimized W:BiVO4 photoanode and the micromorph (a-Si:H/nc-Si:H) cell. This record efficiency is attributed to the increased performance of the BiVO4 photoanode, which is the limiting factor in this hybrid PEC/PV device, as well as better spectral matching between BiVO4 and the nc-Si:H cell.
authors.affiliation: Photovoltaic Materials and Devices (PVMD) Laboratory, Delft University of Technology, Mekelweg 4, 2628 CD, Delft (The Netherlands); Joint Center for Artificial Photosynthesis (JCAP), California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (USA). l.han@tudelft.nl.
authors.forename: Lihao
authors.initials: L
authors.lastname: Han
authors.forename: Fatwa F
authors.initials: FF
authors.lastname: Abdi
authors.forename: Roel
authors.initials: R
authors.lastname: van de Krol
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.forename: Zhuangqun
authors.initials: Z
authors.lastname: Huang
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Lewerenz
authors.forename: Bernard
authors.initials: B
authors.lastname: Dam
authors.forename: Miro
authors.initials: M
authors.lastname: Zeman
authors.forename: Arno H M
authors.initials: AH
authors.lastname: Smets
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D055668:Photochemical Processes; D012993:Solar Energy; D014638:Vanadates / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; C091754:bismuth vanadium tetraoxide; D014638:Vanadates; D001729:Bismuth
keywords: electrochemistry; photochemistry; silicon; solar cells; water splitting