2D Cairo Pentagonal PdPS: Air-Stable Anisotropic Ternary Semiconductor with High Optoelectronic Performance

Pentagonal 2D materials as a new member in the 2D material family have attracted increasing attention due to the exotic physical properties originating from the unique Cairo pentagonal tiling topology. Herein, the penta-PdPS atomic layers as a new air-stable 2D semiconductor with the unique puckered pentagonal low-symmetry structure are successfully exfoliated from bulk crystals grown via chemical vapor transport (CVT). Notably, 2D penta-PdPS exhibits outstanding electronic and optoelectronic performance under 650 nm laser: high electron mobility of ≈208 cm² V⁻¹ s⁻¹, an ultrahigh on/off ratio of ≈10⁸, a high photoresponsivity of 5.2 × 10⁴ A W⁻¹, a high photogain of 1.0 × 10⁵, an ultrahigh detectivity of 1.0 × 10¹³ Jones, respectively. Significantly, the exceptional puckered pentagonal atomic structure of 2D PdPS makes it strong in-plane anisotropy in optical, electronic, and optoelectronic properties, demonstrating a sizeable anisotropic ratio of carrier mobility and photocurrent with the value of up to 3.9 and 2.3, respectively. These excellent properties make 2D Cairo Pentagonal PdPS a potential candidate in nanoelectronics, optoelectronics, polarized-nanoelectronics, which will significantly promote the development of 2D materials.