(180o) Topological Modifications of Layered Materials for Photonics

Morphological control of layered materials has crucial implications on modern electronics and photonics. However, layered materials do not naturally grow beyond 2D morphologies due to their inherent in-plane symmetry. Organic-inorganic hybrid lattice, however, presents unique crystal structure to tackle this challenge. For instance, layered perovskites readily synergize chemical tunability and solution processability of organics with optical and electronic properties of traditional inorganic crystals. Using layered perovskite as a structural template, I'll present a few molecular templating approaches to manipulate the network topology in the organic sublattice and achieve exciting morphological control on layered materials beyond 2D morphologies.

The first section discusses the creation of 1D organic network in layered perovskites using robust and directional hydrogen bonding from aromatic carboxylic acids. This molecular templating method restricted the crystal growth along all directions except for a designed primary axis (1). Our approach is widely applicable to synthesize a range of high-quality layered perovskite nanowires with large aspect ratios and tunable chemical compositions, including the deterministic synthesis of longitudinal heterostructures.

The second half discusses the photonic application of these 2D perovskite nanowires, which begins with a comparison of optically pumped lasing between lead and tin-based layered perovskites. In lead-based candidates, the lasing threshold is often constrained by the strong exciton-phonon interaction or Auger re-combination. Enhanced lasing performances have been pursued in quasi-2D systems (2). Lead-free tin-iodide-based candidates may exhibit lasing performances surpassing those of their lead counterparts, as has been shown in recent studies (3).

Indeed, topologically modified 2D perovskite nanowires form exceptionally well-defined and flexible cavities that exhibited a wide range of unusual optical properties beyond those of conventional perovskite nanowires, including anisotropic emission polarization and low-loss waveguiding. Notably, they also facilitated efficient light amplification (below 20 μJ/cm²) in 2D tin-iodide nanowires at 80K (1).

At the end, new approaches will be discussed to engineer the morphology of layered materials beyond 2D and 1D to create morphological chirality. In addition, recent progresses will be covered achieving room-temperature and ambient-stable plasmonic lasing in quasi-2D tin-iodide perovskites.

References

(1) Shao, W., et al. Science, 2024, 384(6669), 1000–1006. https://doi.org//10.1126/science.adl0920

(2) Park, J. Y., et al. Nature Chemistry, 2023, 15, 1745–1753. https://doi.org/10.1038/s41557-023-01311-0

(3) Li, Y., et al. Science Advances, 2023, 9, eadh0517. https://doi.org/10.1126/sciadv.adh0517