A Molecular Clamp Approach to Layered Halide Perovskite Nanowires

Layered materials can be exfoliated into atomically thin 2D sheets or further fragmented into quantum dots, forming the foundation of numerous technology breakthroughs since the discovery of graphene. However, achieving 1D nanostructures from these materials with inherent in-plane symmetry remains a demanding yet rewarding endeavor. To date, only a few material-specific top-down methods exist, such as creating 1D nanoribbons of graphene and transition metal dichalcogenides through physical or chemical etching and unzipping from carbon nanotubes. The pursuit for a simpler and more universal bottom-up approaches with superior tunability, scalability, and capabilities to create precise and complex epitaxial structures therefore continues, necessitating a fundamental redesign of the crystal growth mechanism.<br/> <br/>Here, we addressed this demand using organic-inorganic hybrid layered perovskites as a model system. Distinct from inorganic layered materials, hybrid semiconductors allow the incorporation of tailor-designed organic spacers with directional supramolecular synthons that communicate beyond single-molecule level. In this regard, a new “molecular clamp” approach is proposed to restrict crystal growth along all crystallographic directions except for [110] and thus to regulate 1D nanowire growth. Our approach is widely applicable to synthesize a range of high-quality 2D perovskite nanowires with large aspect ratios and tunable chemical compositions. These nanowires form exceptionally well-defined and flexible cavities that exhibit versatile unusual optical properties beyond conventional perovskite nanowires including anisotropic emission polarization, low-loss waveguiding (below 3 dB/mm), and efficient low-threshold light-amplification (below 20 µJ/cm²). Our approach highlights the unique structural tunability of organic-inorganic hybrid semiconducting materials by synergizing the merits of each, which also brings unprecedented morphological control to layered materials.