Sonication-assisted synthesis of semiconducting atomic crystals of germanium monoselenide: An isostructural and isoelectronic analog of black phosphorous

TL;DR

This paper reports a sonication-assisted method to synthesize stable, atomically thin germanium monoselenide sheets with tunable optical properties, suitable for optoelectronic applications, and confirms their high crystallinity and environmental stability.

Contribution

It introduces a novel sonication-assisted exfoliation technique for GeSe, producing high-quality, stable 2D sheets with layer-dependent optical properties, advancing 2D material synthesis.

Findings

Successful synthesis of atomically thin GeSe sheets

High crystallinity and environmental stability of exfoliated sheets

Layer-dependent optical bandgap suitable for solar applications

Abstract

Monochalcogenides of germanium (or tin) are considered as stable isoelectronic and isostructural analogue of black phosphorous. Their two-dimensional (2D) forms have been just predicted to shown strong thickness-dependent physical properties, and even indirect to direct band gap crossover at the monolayer limit. Here, we demonstrate the synthesis of atomically thin GeSe by direct sonication-assisted exfoliation of bulk microcrystalline powders in solvents. The exfoliated few-layer GeSe sheets characterize high crystallinity with lateral sizes over 100 nm and, importantly, strong resistance against oxidation and degradation in ambient conditions. Density functional theory calculation combined with optical characterizations confirm the layer-number dependent optical bandgap, which, for few-layer sheets, is optimal for solar light harvesting, and promising for relevant applications, such as optoelectronics and photonics.