Computational design of thermoelectric alloys through optimization of transport and dopability

• Published in: Materials horizons Vol. 9; no. 2; pp. 72 - 73
• Main Authors: Qu, Jiaxing, Balvanz, Adam, Baranets, Sviatoslav, Bobev, Svilen, Gorai, Prashun
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 07.02.2022; Royal Society of Chemistry (RSC)
• Subjects: Alloying; Alloys; Composition; Conduction bands; Crystallography; Design defects; Design optimization; Electronic structure; Energy storage; First principles; Lattice parameters; Material properties; Photovoltaic cells; Point defects; Thermoelectric materials; Thermoelectricity; Transport properties
• ISSN: 2051-6347; 2051-6355
• DOI: 10.1039/d1mh01539g

Alloying is a common technique to optimize the functional properties of materials for thermoelectrics, photovoltaics, energy storage etc. Designing thermoelectric (TE) alloys is especially challenging because it is a multi-property optimization problem, where the properties that contribute to high TE performance are interdependent. In this work, we develop a computational framework that combines first-principles calculations with alloy and point defect modeling to identify alloy compositions that optimize the electronic, thermal, and defect properties. We apply this framework to design n-type Ba 2(1− x ) Sr 2 x CdP 2 Zintl thermoelectric alloys. Our predictions of the crystallographic properties such as lattice parameters and site disorder are validated with experiments. To optimize the conduction band electronic structure, we perform band unfolding to sketch the effective band structures of alloys and find a range of compositions that facilitate band convergence and minimize alloy scattering of electrons. We assess the n-type dopability of the alloys by extending the standard approach for computing point defect energetics in ordered structures. Through the application of this framework, we identify an optimal alloy composition range with the desired electronic and thermal transport properties, and n-type dopability. Such a computational framework can also be used to design alloys for other functional applications beyond TE. We develop a computational framework to guide the systematic optimization of transport properties and dopability of thermoelectric alloys.