In Situ Solution-Grown Halide Perovskite Single Crystals with Epitaxial Heterojunction Structures for Efficient Photodetection

In comparison with monocomponent perovskite single crystals, the heterojunctions of perovskite single crystals provide great chances to tune the optoelectronic properties. In this work, we develop an in situ solution growth approach to fabricate perovskite single-crystal heterojunctions with different compositions, which are MAPbCl₃@MAPbBr₃, CsPbBr₃@MAPbBr₃, and CsPbBr₃@MAPbCl₃. It was found that the as-formed gradient interface with mixed halogen components plays an important role in releasing the lattice mismatch for the in situ growth. Benefiting from the quasi-type II-like energy level alignment between MAPbCl₃and MAPbBr₃single-crystal counterparts, the heterojunction-based device exhibited an enhanced responsivity of 0.28 mA/W and a specific detectivity of over 10⁹Jones under the photovoltaic working mode even with a 1 mm electrode distance. This work provides a facile route to fabricate functional perovskite single crystals with rational design for photodetection applications.