Atom-triggered epitaxial growth of Bi-based perovskite heterojunctions for promoting interfacial charge transfer

The construction of high-quality heterojunction with staggered band structure and close-contact interface, to satisfy both the thermodynamic and dynamic prerequisites of charge transfer, is the key to improve the charge separation of halide perovskites . The in situ growth of perovskite heterojunction via cosharing atoms provides an appealing solution to tackle this dilemma, but it remains a big challenge owing to the lack of appropriate precursors. Here, we design a novel visible-light responsive Co x Bi 2−x O 2 CO 3 nanosheet , and use it as self-template to epitaxially grow Cs 3 Bi 2 Br 9 nanosheet . It is revealed that close-contact 2D/2D heterointerfaces with strong chemical and electronic coupling are built via Bi atom bridge. Moreover, incorporating Co 3+ into Bi 2 O 2 CO 3 plays critical roles in heterojunction growth by regulating both the electronic structure and growth dynamics of Cs 3 Bi 2 Br 9 . Triggered by the effect of Co and the matched Bi lattice with Cs 3 Bi 2 Br 9 , the Co x Bi 2−x O 2 CO 3 /Cs 3 Bi 2 Br 9 heterojunction can drive the fast Z-scheme transfer and separation of photoexcited charge carriers.