Weak Interlayer Interaction in 2D Anisotropic GeSe₂

Abstract

Germanium diselenide (GeSe2) has recently emerged as a new member of in‐plane anisotropic 2D materials, notable for its wide bandgap of 2.74 eV, excellent air stability, and high performance in polarization‐sensitive photodetection. However, the interlayer interaction in GeSe2 has never been reported, which usually plays an important role in layer‐number‐dependent physical properties. Here, the interlayer coupling in GeSe2 is systematically investigated from theory to experiment. Unexpectedly, all of density functional theory (DFT) calculations about layer‐dependent band structures, cleavage energy, binding energy, translation energy, and interlayer differential charge density demonstrate the much weaker interlayer interaction in GeSe2 when compared with black phosphorus (BP). Furthermore, both thickness‐dependent and temperature‐dependent Raman spectra of GeSe2 flakes, which exhibit no detectable changes of Raman peaks with the increase in thickness and a small first‐order temperature coefficient of −0.0095 cm−1 K−1, respectively, experimentally confirm the weakly coupled layers in GeSe2. The results establish GeSe2 as an unusual member of in‐plane anisotropic 2D materials with weak interlayer interaction.

Strong In-Plane Anisotropic SiP2 as a IV–V 2D Semiconductor for Polarized Photodetection

“…Due to the intrinsic indirect optical band gap, the PL intensity of SiP 2 was weak under 532 nm photoexcitation, and the PL peaks demonstrated an obvious redshift (decreasing band gap) from few-layers to bulk SiP 2 (Figure S5). Furthermore, the temperature-dependent PL and Raman spectra of 2D SiP 2 flake were also recorded to study the excitonic transitions, thermal quenching, phonon vibration, and interlayer coupling. − The broad emission at ∼1.97 eV is the most efficient transition process (Figure d), which corresponds to the near-band-edge emission process. At temperatures from 80 to 300 K, the near-band-edge emission peak induced by the band-to-band transition demonstrated an obvious redshift due to the increased phonon interaction and lattice expansion .…”

Ultrathin 2D ternary Bi2Te2Se flakes for fast-response photodetectors with gate-tunable responsivity

“…Raman spectroscopy is an effective tool to investigate the materials' characteristics including crystal structure, lattice symmetry, molecular vibration mode and relative interaction between layers [37][38][39]. The ternary BTS demonstrates similar vibration modes (A 1g…”

GeSe thin-film solar cells

“…GeSe is a member of group-VI monochalcogenides (SnS, SnSe, GeS and GeSe), known as phosphorene analogues. [35][36][37][38] Recently, GeSe has been widely investigated in photodetectors, [39][40][41][42][43][44][45][46] ovonic threshold switching devices, [47][48][49][50] PEC water splitting, 51 gas sensors, 52 field effect transistors (FETs) [53][54][55] and photovoltaics. 33,56,57 Among these applications, GeSe displays great potential in the field of photovoltaics due to its excellent material, optical and electrical properties.…”