Energy band structure peculiarities and luminescent parameters of CeX3 (X = Cl, Br, I) crystals

Abstract The energy band structure of CeX3 (X = Cl, Br, I) crystals have been calculated by the methods of density functional theory using projector augmented waves and hybrid functional of the exchange-correlation interaction PBE0. The valence bands of the investigated crystals are confirmed to be formed by halogen np-states, and the 5d conduction bands formed by 5d1 and 5d2 Ce3+ subbands with strongly different effective masses of charge carriers (particularly 3.6 m0 and 0.5 m0 for CeCl3). Large effective masses of electrons in 5d1 states cause the appearing of Frenkel self-trapped excitons. 4f - cerium states form a single narrow band, which is located above the top of the valence band. The energy band structure of CeX3 (X = Cl, Br, I) crystals can be described within the model according to which the energy structure is the result of the electron energy states superposition in the field of 4f0 and npX0 holes.