TY - JOUR
T1 - Defect Segregation and Its Effect on the Photoelectrochemical Properties of Ti-Doped Hematite Photoanodes for Solar Water Splitting
AU - Scherrer, Barbara
AU - Li, Tong
AU - Tsyganok, Anton
AU - Döbeli, Max
AU - Gupta, Bhavana
AU - Malviya, Kirtiman Deo
AU - Kasian, Olga
AU - Maman, Nitzan
AU - Gault, Baptiste
AU - Grave, Daniel A.
AU - Mehlman, Alexander
AU - Visoly-Fisher, Iris
AU - Raabe, Dierk
AU - Rothschild, Avner
N1 - Funding Information:
The research leading to these results has received funding from the Ministry of Science and Technology of Israel (grant no. 3-14423). B.S. acknowledges support from Marie-Sklodowska-Curie Individual Fellowships no. 656132. T.L. thanks the Alexander von Humboldt Foundation for a postdoctoral fellowship and acknowledges funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation), Projektnummer 388390466, TRR 247 (C4). B.G is grateful to the Blaustein Center for Scientific Cooperation (BIDR, BGU) for a postdoctoral fellowship. Some of the experiments reported in this work were carried out using central facilities at the Technion’s Hydrogen Technologies Research Laboratory (HTRL) supported by the Adelis Foundation and the Solar Fuels I-CORE program of the Planning and Budgeting Committee and the Israel Science Foundation (grant no. 152/11). The authors acknowledge support from the electron microscopy center of Technion (MIKA).
Publisher Copyright:
Copyright © 2019 American Chemical Society.
PY - 2020/2/11
Y1 - 2020/2/11
N2 - Optimizing the photoelectrochemical performance of hematite photoanodes for solar water splitting requires better understanding of the relationships between dopant distribution, structural defects, and photoelectrochemical properties. Here, we use complementary characterization techniques including electron microscopy, conductive atomic force microscopy (CAFM), Rutherford backscattering spectroscopy (RBS), atom probe tomography (APT), and intensity-modulated photocurrent spectroscopy (IMPS) to study this correlation in Ti-doped (1 cat. %) hematite films deposited by pulsed laser deposition (PLD) on F:SnO2 (FTO)-coated glass substrates. The deposition was carried out at 300 °C followed by annealing at 500 °C for 2 h. Upon annealing, Ti was observed by APT to segregate to the hematite/FTO interface and into some hematite grains. Since no other pronounced changes in microstructure and chemical composition were observed by electron microscopy and RBS after annealing, a nonuniform Ti redistribution seems to be the reason for reduced interfacial recombination in the annealed films, as observed by IMPS. This results in a lower onset potential, higher photocurrent, and larger fill factor with respect to the as-deposited state. This work provides atomic-scale insights into the microscopic inhomogeneity in Ti-doped hematite thin films and the role of defect segregation in their electrical and photoelectrochemical properties.
AB - Optimizing the photoelectrochemical performance of hematite photoanodes for solar water splitting requires better understanding of the relationships between dopant distribution, structural defects, and photoelectrochemical properties. Here, we use complementary characterization techniques including electron microscopy, conductive atomic force microscopy (CAFM), Rutherford backscattering spectroscopy (RBS), atom probe tomography (APT), and intensity-modulated photocurrent spectroscopy (IMPS) to study this correlation in Ti-doped (1 cat. %) hematite films deposited by pulsed laser deposition (PLD) on F:SnO2 (FTO)-coated glass substrates. The deposition was carried out at 300 °C followed by annealing at 500 °C for 2 h. Upon annealing, Ti was observed by APT to segregate to the hematite/FTO interface and into some hematite grains. Since no other pronounced changes in microstructure and chemical composition were observed by electron microscopy and RBS after annealing, a nonuniform Ti redistribution seems to be the reason for reduced interfacial recombination in the annealed films, as observed by IMPS. This results in a lower onset potential, higher photocurrent, and larger fill factor with respect to the as-deposited state. This work provides atomic-scale insights into the microscopic inhomogeneity in Ti-doped hematite thin films and the role of defect segregation in their electrical and photoelectrochemical properties.
UR - http://www.scopus.com/inward/record.url?scp=85080045949&partnerID=8YFLogxK
U2 - 10.1021/acs.chemmater.9b03704
DO - 10.1021/acs.chemmater.9b03704
M3 - Article
AN - SCOPUS:85080045949
VL - 32
SP - 1031
EP - 1040
JO - Chemistry of Materials
JF - Chemistry of Materials
SN - 0897-4756
IS - 3
ER -
