Berlin 2024 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 51: Functional Semiconductors for Renewable Energy Solutions II
HL 51.6: Talk
Friday, March 22, 2024, 10:45–11:00, ER 325
Engineering interfaces for efficient and stable photoelectrochemical energy conversion — •Julian Müller1,2, Matthias Kuhl1,2, Ian D. Sharp1,2, and Johanna Eichhorn1,2 — 1Walter Schottky Institute, Technische Universität München, Germany — 2Physics Department, TUM School of Natural Sciences, Technische Universität München, Germany
For photoelectrochemical (PEC) energy conversion, transition metal nitrides emerged recently as a promising alternative to commonly studied metal oxides. Among others, tantalum nitride (Ta3N5) is highly interesting due to its bandgap of 2.1 eV, suitable band alignment for water splitting, and theoretical photocurrent density of 12.9 mA/cm2. However, Ta3N5 rapidly degrades under operation conditions due to self-oxidative decomposition in aqueous electrolytes. Here, we interfaced Ta3N5 photoanodes with cobalt oxide (CoOx) surface layers to overcome the current stability limitations. Specifically, we leveraged plasma-enhanced atomic layer deposition (PE-ALD) to deposit stable, conformal, and ultra-thin protection layers which are simultaneously robust and electrochemically active. To engineer efficient interfaces between photoelectrode and protection layer, we developed one- and two-step annealing processes in different gas atmospheres and correlated the change in interface properties to their PEC characteristics. Overall, this study highlights the beneficial role of the protection layer on the photoelectrode stability, but also emphasizes the dominating role of interface properties on the efficiency and the need for controlled interface engineering.
Keywords: nitrides; annealing; atomic layer deposition; photoelectrochemical energy conversion; oxides