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 π antibonding interactions in Se–Se dimers, and a resultant two order of magnitude difference in predicted mobilities between in- and out-of-plane directions. 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.