Synthesis, Structure, and Properties of CuBiSeCl <sub>2</sub> : A Chalcohalide Material with Low Thermal Conductivity
Cara J. Hawkins, Jon A. Newnham, Batoul Almoussawi, Nataliya L. Gulay, Samuel L. Goodwin, Marco Zanella, Troy D. Manning, Luke M. Daniels, Matthew S. Dyer, T. D. Veal, John B. Claridge, Matthew J. Rosseinsky
Abstract
High Resolution Image Download MS PowerPoint Slide Mixed anion halide-chalcogenide materials have recently attracted attention for a variety of applications, owing to their desirable optoelectronic properties. We report the synthesis of a previously unreported mixed-metal chalcohalide material, CuBiSeCl 2 ( Pnma ), accessed through a simple, low-temperature solid-state route. The physical structure is characterized through single-crystal X-ray diffraction and reveals significant Cu displacement within the CuSe 2 Cl 4 octahedra. The electronic structure of CuBiSeCl 2 is investigated computationally, which indicates highly anisotropic charge carrier effective masses, and by experimental verification using X-ray photoelectron spectroscopy, which reveals a valence band dominated by Cu orbitals. The band gap is measured to be 1.33(2) eV, a suitable value for solar absorption applications. The electronic and thermal properties, including resistivity, Seebeck coefficient, thermal conductivity, and heat capacity, are also measured, and it is found that CuBiSeCl 2 exhibits a low room temperature thermal conductivity of 0.27(4) W K –1 m –1, realized through modifications to the phonon landscape through increased bonding anisotropy.