Electronic and optical properties of Sc2C(OH)2 with phenylsulfonic groups: A first-principles study

Abstract

Polystyrene sulfonic acid (PSS) polymer thin film can be applied to the surface passivation of Si-based semiconductor devices because of its low cost and the ability to be fabricated without the need for extreme temperatures or high vacuum. Here, the phenylsulfonic groups (–pSO3H, a typical part of PSS) were grafted onto the Sc2C(OH)2 the surface to form Sc2C(OH)2–pSO3H. The electronic structure and optical properties were investigated by first-principles calculations. The results show that Sc2C(OH)2–pSO3H is a direct bandgap semiconductor material with a bandgap of 0.99 eV, which is higher than that of Sc2C(OH)2. The bandgap of Sc2C(OH)2–pSO3H has a small change by replacing cation H of –pSO3H with Li, Na and K, indicating that the Sc2C(OH)2–pSO3H maintains its semiconductor properties. The reason is that the conduction band minimum (CBM) state and the valence band maximum (VBM) are mainly determined by the contribution of C 2p states and Sc 3d states of the main body Sc2C(OH)2. Versus the conventional photovoltaic material Si, the absorption coefficient of Sc2C(OH)2–pSO3H is very high, thus resulting in a maximum photoelectric conversion efficiency of up to 31 %. These results suggest promising 2D visible light absorption materials that are photovoltaics in solar cells.