Deciphering the stacking language of honeycomb bilayer materials

Research into two-dimensional materials and their stacking configurations has significantly increased in recent years. Experimental and theoretical studies have revealed unexpected phenomena across various stacking forms. However, a major challenge in studying layered structures is the ambiguous nomenclature in the literature, which complicates comparisons between systems and may lead to omissions of specific stackings. This review addresses the need for a unified framework to categorize stacking arrangements of bilayer honeycomb materials from groups 13–15. We use a uniform ABC notation for nomenclature to facilitate comparative analysis while examining its limitations and emphasizing the need for a robust notation.