Tuning transport performance in two-dimensional metal-organic framework semiconductors: Role of the metal d band

Hybrid metal-organic frameworks have some exotic electronic properties, such as extremely high electron and hole mobilities and nontrivial topological properties. Here, we systematically study the electronic properties of the two-dimensional metal-organic framework semiconductors (MOFSs) (M3S6C6, M = Mg, Ca, Zn, Cd, Ge, and Sn) using the first principles calculations. We find that the metal d band is important in determining the hole transport properties of M3S6C6. The p-d hybridization between the metal d and S-C p bands will delocalize the wavefunction of the band edge states and reduce the effective mass. From group IIA (Mg, Ca) to IVA (Ge, Sn) to IIB (Zn, Cd), as the p-d coupling increases, the hole effective masses dramatically decrease. Additionally, due to the fact that the conduction band minimum of group IIB (Zn, Cd) MOFSs is mainly dominated by the delocalized M s state, they also have the very small electron effective mass. Therefore, the 2D group IIB (Zn, Cd) MOFSs have excellent hole and elec...