Abstract

The spirally rolled 2D material based light-trapping nanocavity structure with QDs as scattering centers achieves unprecedently low lasing threshold (~0.008 kW cm^-2) and 12 fold brighter parallel-polarized luminescence than that of the perpendicular one.

Twisting the morphology of the atomically thin layer of 2D materials introduces some striking physio- chemical phenomena which are significantly absent in their bulk as well as sheet counterpart. By exploiting the flexural strength, these 2D materials (eg. MoS₂, WS₂) can be stacked up into heterostructure, buckled up to form wavy structure, rolled up into 1D, or wrapped up into the 0D structure. Different dimensional van der Waals structure tunes the energy bandgap and hence the corresponding carrier mobility. Spirally rolling of 2D material in a unidirectional nanoscroll (NS) structure can confine the motion of the electron in the 1D axis without having any external perturbation. Photonic confinement in these nanocavities stimulates coherent lasing actions with an unprecedently low threshold. This helical 1D structure predominantly localizes the excitons in the circumferential direction giving rise to polarized photosensitivity. Upon hybridizing with high yield quantum dots, type–II band alignments are formed at the heterostructured (QD/2D) interface. The subsequent presence of strong photoabsorptive QDs generates an ample amount of excitons which enhances the photosensitivity of the NS. Thus our approach to form spirally rolled hybridized NS structure introduces exotic physical phenomena which are utilized to develop novel high-performance flexible devices toward realistic applications.

© 2021 The Author(s)