Dresden 2026 – scientific programme
Parts | Days | Selection | Search | Updates | Downloads | Help
MM: Fachverband Metall- und Materialphysik
MM 4: Materials for the Storage and Conversion of Energy I
MM 4.2: Talk
Monday, March 9, 2026, 10:45–11:00, SCH/A216
Defect-driven carrier dynamics in tantalum nitride photoelectrodes — •Lukas M. Wolz1, Johannes Dittloff1,2, Laura I. Wagner1,2, Julius Kühne1,2, Luc-Fabrice Tremel1, Lina M. Todenhagen1,2, Lissa Eyre1,2, Felix Deschler1,2,3, Ian D. Sharp1,2, and Johanna Eichhorn1 — 1Physics Department, TUM School of Natural Sciences, Technische Universität München, Germany — 2Walter Schottky Institute, Technische Universität München, Germany — 3Institute for Physical Chemistry, Heidelberg University, Germany
Tantalum nitride (Ta3N5) is a widely studied semiconductor for solar-driven water splitting. Yet, experimentally realized efficiencies often remain below theoretical limits largely because native and impurity-related defect states alter charge carrier dynamics by promoting trapping and recombination. Here, we investigate how distinct defect properties in Ta3N5 thin films govern ultrafast photocarrier behavior using femtosecond transient absorption spectroscopy, complemented by photoluminescence (PL) and PL excitation measurements. Ta3N5 photoelectrodes were synthesized by annealing TaOx, TaNx, and Ta precursor films in NH3, enabling systematic control over shallow and deep defect state concentrations. The controlled defect properties allow us to disentangle the roles of nitrogen vacancies and oxygen-related defects in shaping carrier dynamics. Our results reveal that deep defects function as efficient trapping and recombination centers for free carriers. Here, we correlate ultrafast spectroscopy with complementary optical and photoelectrochemical data.
Keywords: Photoinduced water splitting; Ultrafast Spectroscopy; Defects; Optical Properties; Deep level traps