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HL: Fachverband Halbleiterphysik
HL 7: Poster I
HL 7.4: Poster
Monday, March 27, 2023, 13:00–15:00, P2/EG
Polaron Transport in BiVO4 — •Sven Doll, Tim Rieth, David Vogl, Viktoria F. Kunzelmann, Ian D. Sharp, and Martin S. Brandt — Walter Schottky Institut and School of Natural Sciences, Technische Universität München, 85748 Garching
Bismuth vanadate (BiVO4) is a promising photoelectrode material for solar-to-fuel conversion. This semiconductor is particularly interesting considering its strong visible light absorption, efficient charge carrier separation, and favorable quasi-Fermi-level alignment with relevant redox potentials. However, temperature-dependent photoconductivity measurements indicate thermally-activated hopping transport of small polarons, with transport barriers of several hundred meV. To gain further insight into charge carrier transport and the nature of these polaronic states, we explore whether the hopping of the small polarons in BiVO4 is spin-dependent using electrically detected magnetic resonance. Since such spin-dependent signals are known (e.g., from similar experiments on doped crystalline silicon) to critically depend on the charge carrier density, we evaluate the possibility to use the persistent photoconductivity of BiVO4 to tune the polaron density. This technique may provide valuable insights into the microscopic transport processes in modern photoelectrodes used for energy conversion. This work was supported by the DFG under Germany’s Excellence Strategy - EXC 2089/1 - 390776260.