Semiconducting silicon–phosphorus frameworks for caging exotic polycations

Abstract

A series of novel semiconductors AAe₆Si₁₂P₂₀X (A = Na, K, Rb, Cs; Ae = Sr, Ba; X = Cl, Br, I) is reported. Their crystal structures feature a tetrahedral Si–P framework with large zeolite-like pores hosting two types of cations, monoatomic A⁺ and unprecedented octahedral X@Ae₆¹¹⁺. Mixing of the A and Ba cations was detected by single crystal X-ray diffraction and confirmed by multinuclear solid state NMR. The reported compounds are highly stable semiconductors with a bandgap range from 1.4 to 2.0 eV.