Berlin 2018 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 3: Oxide Semiconductors for Novel Devices (Focussed Session): Session I
DS 3.3: Vortrag
Montag, 12. März 2018, 10:00–10:15, E 020
Defect Investigation of CuBi2O4 Photocathodes for Solar Water Splitting — •Michael Sahre, Marlene Lamers, Matthias Müller, Fatwa F. Abdi, and Roel van de Krol — Institute for Solar Fuels, Helmholtz-Zentrum Berlin, Berlin, Germany
The rise of global warming requires the development of novel sustainable carbon-free energy sources. One promising method is by directly converting water into hydrogen and oxygen using sunlight; the process is usually called "solar water splitting". In such process, a semiconductor is used to absorb the light, separate the photo-generated charge carriers, and produce hydrogen and/or oxygen on its surface. A promising candidate as the semiconductor is CuBi2O4 due to its suitable bandgap of 1.8 eV (theoretical solar-to-hydrogen efficiency of 24 %) and favorable band positions. [1,2] However, poor charge carrier transport and surface charge transfer limit the photocurrent. [2]
In this work, we attempt to alleviate the above-mentioned limitations by modulating the defects in CuBi2O4 thin films through various annealing conditions. Time resolved microwave conductivity measurements show an improved charge carrier transport after the high temperature annealing. Simultaneously, this treatment leads to a surface modification and enhanced electron transfer from the semiconductor into the electrolyte, so that the AM1.5 photocurrent is significantly increased. The interplay between the annealing condition, defect formation and photoelectrochemical performance will be discussed.
[1] Chen et al., J. Mater. Res. 25 (2010) 3
[2] Berglund et al., Chem. Mater. 28 (2016) 4231