Berlin 2024 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 36: Poster III
HL 36.52: Poster
Wednesday, March 20, 2024, 18:00–20:30, Poster E
Atomic Layer Deposition of Pt-doped Ta2O5 Coatings for Photoelectrochemical Water Splitting — •Julius Kleusberg1,2, Tim Rieth1,2, Guanda Zhou1,2, and Ian Sharp1,2 — 1Walter Schottky Institute, TU Munich, Garching, Germany — 2TUM School of Natural Sciences, TU Munich, Garching, Germany
Photoelectrochemical (PEC) water splitting provides a promising avenue for transitioning from a fossil fuel-based economy towards low-carbon alternatives. In PEC devices, photoabsorbers are immersed into an electrolyte, absorb light, generate and separate electron-hole pairs, and thereby drive the water splitting reactions. However, the chemical instability of many efficient photoabsorbers under PEC conditions remains a critical challenge. Consequently, a quest for functional coatings protecting the photoabsorber arise. Tantalum oxide (Ta2O5) emerged as promising protective material due to its high electrochemical inertness and full transparency to the solar spectrum. However, as wide bandgap semiconductor, Ta2O5 suffers from low electrical conductivity that prevents efficient charge transport to the catalytic surface. In this study, we introduce Pt sub-cycles in a Ta2O5 ALD process to achieve Pt-doped Ta2O5 thin films with enhanced electrical conductivity. We tailor the Pt-concentration via the sub-cycle ratio and thereby introduce additional states at the valance band edge that shift the Fermi-level downwards. Finally, we apply the developed Pt-doped Ta2O5 coatings on BiVO4 photoanodes, analyse PEC improvements, and, ultimately, demonstrate doped ALD coatings as a promising way towards durable photoelectrochemical water splitting.
Keywords: ALD; PEC; Protection Layer; Doping; Transition metal oxides