Berlin 2024 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 51: Functional Semiconductors for Renewable Energy Solutions II
HL 51.2: Vortrag
Freitag, 22. März 2024, 09:45–10:00, ER 325
The influence of structural dynamics on the macroscopic properties of the solar harvesting nitride CuTaN2 — •Franziska S. Hegner1, Adi Cohen2, Stefan S. Rudel3, Silva Kronawitter1, Manuel Grumet1, Xiangzhou Zhu1, Roman Korobko2, Lothar Houben2, Chang-Ming Jiang1, Wolfgang Schnick3, Gregor Kieslich1, Omer Yaffe2, Ian D. Sharp1, and David A. Egger1 — 1TU Munich, Germany — 2Weizmann Institute of Science, Israel — 3LMU Munich, Germany
Ternary nitrides are an emerging class of materials that show large potential for solar energy conversion because of their favourable light absorption and carrier transport properties. Yet, they are relatively unexplored due to their metastability and the comparative difficulty of their synthesis. Here, we studied the representative copper tantalum nitride, CuTaN2, a particularly promising visible light absorbing semiconductor, using a combination of theoretical and experimental methods. Harmonic phonon calculations and finite-temperature Raman scattering experiments show that its structural dynamics display highly anharmonic character. We first elucidated the microscopic aspects of the atomic motions with ab initio Molecular Dynamics and then investigated their impact on their macroscopic characteristics. The latter are strongly influenced by the anharmonic nuclear motions, leading to negative thermal expansion and, especially important, a significant increase of the fundamental bandgap. This highlights that structural dynamics play a crucial role for the functional properties of energy materials.
Keywords: Ternary nitrides; Structural dynamics; Solar energy conversion; Ab initio molecular dynamics; Raman scattering