Electronic structures and optical properties of wurtzite type LiBSe2 (B=Al, Ga, In): A first-principles study

The electronic structures of three wurtzite type isostructural compounds LiBSe2 (B=Al, Ga, In) are studied by the density functional theory (DFT). The results reveal that the presence of Li cations has direct influence on neither the band gaps (Eg) nor the bonding levels, but plays an important role in the stabilization of the structures. The band structures and densities of states (DOS) are analyzed in detail, and the band gaps of LiBSe2 adhere to the following trend Eg(LiAlSe2)>Eg(LiGaSe2)>Eg(LiInSe2), which is in agreement with the decrease of the bond energy of the corresponding Se 4p–B s antibonding orbitals. The role of the active s electrons of B element on the band gaps is also discussed. Finally, the optical properties are predicted, and the results would be a guide to understand the experiments.