title: Atomically Altered Hematite for Highly Efficient Perovskite Tandem Water-Splitting Devices.
abstract: Photoelectrochemical (PEC) cells are attractive for storing solar energy in chemical bonds through cleaving of water into oxygen and hydrogen. Although hematite (α-Fe2O3) is a promising photoanode material owing to its chemical stability, suitable band gap, low cost, and environmental friendliness, its performance is limited by short carrier lifetimes, poor conductivity, and sluggish kinetics leading to low (solar-to-hydrogen) STH efficiency. Herein, we combine solution-based hydrothermal growth and a post-growth surface exposure through atomic layer deposition (ALD) to show a dramatic enhancement of the efficiency for water photolysis. These modified photoanodes show a high photocurrent of 3.12 mA cm-2at 1.23 V versus RHE, (>5 times higher than Fe2O3) and a plateau photocurrent of 4.5 mA cm-2at 1.5 V versus RHE. We demonstrate that these photoanodes in tandem with a CH3NH3PbI3perovskite solar cell achieves overall unassisted water splitting with an STH conversion efficiency of 3.4 %, constituting a new benchmark for hematite-based tandem systems.
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798, Singapore.
authors.lastname: Gurudayal
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798, Singapore.
authors.forename: Rohit Abraham
authors.initials: RA
authors.lastname: John
authors.affiliation: Energy Research Institute @NTU, ERI@N, Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore, 637553, Singapore.
authors.forename: Pablo P
authors.initials: PP
authors.lastname: Boix
authors.affiliation: Laboratory of Photonics and Interfaces, Department of Chemistry and Chemical Engineering, Swiss Federal Institute of Technology, Station 6, 1015, Lausanne, Switzerland.
authors.forename: Chenyi
authors.initials: C
authors.lastname: Yi
authors.affiliation: Energy Research Institute @NTU, ERI@N, Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore, 637553, Singapore.
authors.forename: Chen
authors.initials: C
authors.lastname: Shi
authors.affiliation: Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.|National Center for Electron Microscopy, Molecular Foundry, Lawrence, Berkeley National Laboratory, Berkeley, CA, 94720, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Scott
authors.affiliation: Energy Research Institute @NTU, ERI@N, Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore, 637553, Singapore.
authors.forename: Sjoerd A
authors.initials: SA
authors.lastname: Veldhuis
authors.affiliation: Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.|National Center for Electron Microscopy, Molecular Foundry, Lawrence, Berkeley National Laboratory, Berkeley, CA, 94720, USA.
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Minor
authors.affiliation: Laboratory of Photonics and Interfaces, Department of Chemistry and Chemical Engineering, Swiss Federal Institute of Technology, Station 6, 1015, Lausanne, Switzerland.
authors.forename: Shaik M
authors.initials: SM
authors.lastname: Zakeeruddin
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798, Singapore.
authors.forename: Lydia Helena
authors.initials: LH
authors.lastname: Wong
authors.affiliation: Laboratory of Photonics and Interfaces, Department of Chemistry and Chemical Engineering, Swiss Federal Institute of Technology, Station 6, 1015, Lausanne, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Grätzel
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore, 639798, Singapore.|Energy Research Institute @NTU, ERI@N, Research Techno Plaza, X-Frontier Block, Level 5, 50 Nanyang Drive, Singapore, 637553, Singapore.
authors.forename: Nripan
authors.initials: N
authors.lastname: Mathews
mesh_terms: D017610:Calcium Compounds; D004563:Electrochemistry / Q000379:methods; D005290:Ferric Compounds / Q000737:chemistry*; D010087:Oxides; D010782:Photolysis; D012993:Solar Energy; D014025:Titanium; D014867:Water / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D005290:Ferric Compounds; D010087:Oxides; D014867:Water; C059910:perovskite; C000499:ferric oxide; D014025:Titanium
keywords: atomic layer deposition; hematite; perovskite solar cell; tandem cell; water splitting