Assessing the Electronic and Optical Properties of Lanthanum Diselenide: a computational study

The lanthanide polychalcogenides are a diverse family of compounds with numerous tuneable properties, but only recently has stoichiometric LaSe2 been proposed as a hole transport material. Clarification over its electronic, optical and transport properties is necessary for its future development as a functional material -- in this work, we perform hybrid Density Functional Theory calculations to examine and assess these properties. We find that LaSe2 has strongly anisotropic hole transport properties due to the valence band maximum comprising pi antibonding interactions in Se-Se dimers, and a resultant 2 order of magnitude difference in predicted mobilities. An indirect gap together with forbidden electronic transitions is predicted to lead to a delayed onset of optical absorption, making LaSe2 a strong candidate for an IR-transparent hole conducting material.