Robust growth of layered Sn2P2S6 nanoplates with strong in-plane optical anisotropy

Abstract

Layered ternary metal phosphorous chalcogenides (TMPCs) with low-symmetry structure have emerged as promising candidates for developing high-performance polarization-sensitive optoelectronics and nonlinear optical systems. The production of highly crystalline TMPCs with well-understood optical anisotropy is essential for their device applications. Herein, we report a robust growth of an anisotropic layered TMPC semiconductor Sn2P2S6 via space-confined chemical vapor deposition. The as-grown high-quality Sn2P2S6 nanoplates with uniform edges but different morphologies are identified as a typical semiconductor with a bandgap of 2.12 eV, and their morphology evolution during the growth can be greatly understood by the kinetic Wulff construction theory. The non-centrosymmetric structure of Sn2P2S6 nanoplates enables their strong optical anisotropies, resulting in giant second-harmonic generation anisotropy with the polarized anisotropic ratio up to 38.9. Additionally, they also indicate pronounced in-plane vibration anisotropy, reflecting the directional phonon responses inherent to their lattice symmetry. This work not only offers a robust synthetic strategy for achieving high-quality TMPC crystals but also suggests the large potential of Sn2P2S6 for polarization-sensitive optoelectronic applications.