fig2

Figure 2. FE-driven band alignment transition in 2D ABP₂X₆ VFSHs. (A) Potential band alignment type of 2D ABP₂X₆ VFSHs. Here, A and B represent two different FE semiconductors in a given VFSH. Two straddling (type-I) band alignments are expressed by purple and cyan squares, and two staggered (type-II) band alignments are labeled by orange and red squares, respectively. A and B denote two different FE semiconductors in a given VFSH; (B) Predicted band alignment type of 55 2D ABP₂X₆ VFSHs in four stable polarization states (i.e., ↑↑, ↑↓, ↓↑, and ↓↓). The inset indicates that these VFSHs are constructed by vdW integration of two distinct 2D ABP₂X₆ FE semiconductors. FE: Ferroelectric; 2D: two-dimensional; VFSHs: vdW FE semiconductor heterojunctions.