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HL: Fachverband Halbleiterphysik
HL 34: Functional semiconductors for renewable energy solutions II (joint session HL/CPP)
HL 34.1: Vortrag
Dienstag, 17. März 2020, 14:00–14:15, POT 151
Small-polaron transport and the role of defects in BiVO4 photoanodes for solar water splitting — •Tim F. Rieth, Viktoria F. Kunzelmann, and Ian D. Sharp — Walter Schottky Institute and Physics Department, TU Munich, Garching, Germany
Photoelectrodes can provide a route to a renewable energy supply by absorbing solar light and, thereby, drive an electrochemical reaction to produce chemical fuels. Bismuth vanadate (BiVO4) exhibits the necessary properties for solar water splitting, namely visible light absorption, efficient charge carrier separation and well positioned band edges, and is the highest performing oxide photoanode to date [1]. Despite these advantages, the performance of BiVO4 is inhibited by a low charge carrier mobility caused by small-polaron formation [2]. In our work, we investigate the limiting thermally activated hopping transport of small-polarons by the determination of the associated energy barrier Eh with temperature-dependent conductivity measurements on polycrystalline BiVO4 thin films. Furthermore, we study how Eh is impacted by intentionally introduced defects such as vacancy defects and hydrogen impurities, which has been shown to greatly enhance the conductivity of BiVO4 [3]. An improved understanding of charge carrier transport and its modification by defects can help to increase the performance of BiVO4 and gives insights that aid in the development of new metal oxide photoelectrodes.
[1] I.D. Sharp et al., ACS Energy Lett. 2, 139 (2017)
[2] A.J.E. Rettie et al., Appl. Phys. lett. 106, 022106 (2015)
[3] J.K. Cooper et al., Chem. Mater. 28, 5761 (2016)