Large‐Scale Ultrastable 2D Inorganic Molecular Crystal BiBr3 and Heterostructures with Superior Photoluminescence Enhancement

Abstract In contrast to conventional atomic crystals, two‐dimensional inorganic molecular crystals (2DIMCs) possess a unique crystal structure composed of small molecules held together by van der Waals force. Such distinctive structure grants them specific chemical and physical properties highly suitable for electronic and optoelectronic applications. However, the synthesis of 2DIMCs has posed significant challenges due to the inherent issues such as uncontrollable growth orientation stemming from their natural crystalline isotropy and poor stability resulting from the weak intermolecular connections. Addressing these obstacles, the preparation of large‐scale and highly‐stable 2DIMC BiBr 3, and its heterostructure are reported here by developing crystallization orientation engineering strategies. This approach has successfully yielded centimeter‐scale 2DIMC BiBr 3 with a clean and dense surface, showcasing exceptional long‐term air‐stability exceeding 80 days. Furthermore, the universal growth of large‐scale 2DIMC BiBr 3 is demonstrated on diverse substrates, including SiO 2 , Al 2 O 3 , and MoS 2 monolayers. Notably, the resultant 2D BiBr 3 /MoS 2 heterostructure exhibits remarkable photoluminescence enhancement. This contribution paves a universal avenue for the mature synthesis of large‐scale 2DIMCs with superior stability, holding great promise for prompting their integration in practical electronic and optoelectronic devices.