Regensburg 2025 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 12: Materials for the Storage and Conversion of Energy
MM 12.1: Vortrag
Dienstag, 18. März 2025, 10:15–10:30, H22
Where Electrons Rest After Dark: Polaron Stability in Opto-Ionic 2D Niobium Titanate — •Christoph Dähn1, Yang Wang2, Risov Das2, Bettina V. Lotsch2, Karsten Reuter1, and Christian Carbogno1 — 1Fritz-Haber-Institut der MPG, Berlin — 2MPI für Festkörperforschung, Stuttgart
Two-dimensional Niobium Titanate in alkaline solution is promising for opto-ionic energy applications, since it can store photo-generated charge carriers over macroscopic time scales. Although experiments suggest polarons to play a key role for charge storage, identifying the atomistic and electronic mechanisms active in this material has so far proved challenging, also due to the intrinsic disorder of this compound. In this work, we shed light on these aspects by performing hybrid density-functional theory calculations. In a first step, we explore the vast amount of possible lattice decorations resulting from the partial occupation of Ti-sites with Nb, from which we identify a representative set of stable configurations for this disordered material. In a second step, we investigate the stability of polarons at different lattice sites in these configurations. To qualitatively rationalize these results, a fuzzy classification scheme [1] is applied to group comparable polarons according to their local environment. This allows us to analyze how the local environment influences polaron stability and, in turn, long-term charge retention and its underlying mechanisms [2].
[1] K. C. Lai et al., J. Chem. Phys. 159, 024129 (2023).
[2] Y. Wang et al., J. Am. Chem. Soc. 146, 25467(2024).
Keywords: Polarons; Opto-Ionic; Battery; Layered Oxides; Disorder