title: Understanding charge transport in non-doped pristine and surface passivated hematite (Fe2O3) nanorods under front and backside illumination in the context of light induced water splitting.
abstract: Hematite (Fe2O3) nanorods on FTO substrates have been proven to be promising photoanodes for solar fuel production but only with high temperature thermal activation which allows diffusion of tin (Sn) ions from FTO, eventually enhancing their conductivity. Hence, there is a trade-off between the conductivity of Fe2O3, and the degradation of FTO occurring at high annealing temperatures (>750 °C). Here, we present a comprehensive study on undoped Fe2O3nanorods under front and back illumination to find the optimum annealing temperature. Bulk/surface charge transport efficiency analysis demonstrates minimum bulk recombination indicating overall high quality crystalline Fe2O3and the preservation of FTO conductivity. Surface recombination is further improved by growing a TiOxoverlayer, which improves the photocurrent density from 0.2 mA cm-2(backside) to 1.2 mA cm-2under front side and 0.8 mA cm-2under backside illumination. It is evident from this study that the performance of undoped and unpassivated hematite nanorods is limited by electron transport, whereas that of doped/passivated hematite nanorods is limited by hole transport.
authors: School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore. lydiawong@ntu.edu.sg.
authors: Prince Saurabh
authors: PS
authors: Bassi
authors: Energy Research Institute @ NTU, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, X-Frontier Block, Level 5, Singapore, 637553, Singapore.
authors: Li
authors: L
authors: Xianglin
authors: Energy Research Institute @ NTU, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, X-Frontier Block, Level 5, Singapore, 637553, Singapore.
authors: Yanan
authors: Y
authors: Fang
authors: School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore. lydiawong@ntu.edu.sg.
authors: Joachim Say Chye
authors: JS
authors: Loo
authors: School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore. lydiawong@ntu.edu.sg and Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK. j.barber@imperial.ac.uk.
authors: James
authors: J
authors: Barber
authors: School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore. lydiawong@ntu.edu.sg.
authors: Lydia Helena
authors: LH
authors: Wong