Two-dimensional monoelemental germanene nanosheets: facile preparation and optoelectronic applications

Abstract

Due to high carrier mobility, excellent stability, and tunable optical properties, 2D monoelemental germanene has attracted considerable attention in recent years. Herein, few-layered 2D germanium nanosheets (GeNS) were obtained via a facile liquid-phase exfoliated method and fabricated as electrode materials to assemble self-powered photo-electrochemical (PEC) type photodetectors. Such 2D GeNS-based PEC-type photodetectors exhibit a responsivity of 7.81 μA W⁻¹, a detectivity of 5.2 × 10⁹ Jones, and the rise and decay times of 0.15 s and 0.76 s, respectively, under simulated light. At the specific wavelength of 380 nm, it demonstrates a responsivity of 340.91 μA W⁻¹ and a detectivity of 1.82 × 10¹¹ Jones. In addition, the GeNS-based PEC-type device also exhibits good air-stability (over one-month). The present work demonstrates low-cost and facile fabrication techniques for preparing 2D monoelemental germanene and suggests that the as-prepared GeNS is a promising candidate for PEC-type photodetector applications.