Phosphorus Nanotubes from Chemical Cleavage

TL;DR

This paper introduces a method to create sulfur-doped phosphorus nanotubes from existing allotropes, demonstrating their structural, electronic, and optical properties for potential optoelectronic applications.

Contribution

It presents a novel chemical cleavage strategy to produce linear sulfur-doped phosphorus nanotubes with tunable properties from known phosphorus allotropes.

Findings

Sulfur doping dissociates covalent bonds, forming free-standing nanotubes.

The nanotubes can sustain up to 18% tensile strain.

Large exciton binding energy of 1.57 eV indicates strong optical properties.

Abstract

We propose a strategy to make phosphorus nanotubes from two well-known phosphorus allotropes: violet phosphorus and fibrous red phosphorus. First-principles calculations show that doping with sulfur dissociates the covalent bonds between tubular phosphorus structures that form bilayers in these allotropes, resulting in free-standing 1D nanotubes. Due to the substitutional nature of the sulfur dopant, the resulting 1D structure is linear, unlike the helical ring structure studied previously. The sulfur sites are situated periodically along the 1D nanotubes and can be further functionalized. Our results show that the S-doped phosphorus nanotube can sustain a tensile strain of up to 18%. The strain also substantially modifies the electronic band gap and the effective mass of carriers. Calculations using the many-body Green's functions (GW) and the Bethe-Salpeter equation (BSE) approaches reveal a large exciton binding energy of 1.57 eV. The one-dimensional nature, linearity, functionalizability, mechanical flexibility, tunability of electronic properties, and large exciton binding energy make this material interesting for applications in optoelectronic devices, solar cells, chemical sensors, and quantum computing.