Developing Ultra-Thin Photodetector Based on Molybdenum Disulfide Nanoribbons

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Developing Ultra-Thin Photodetector Based on Molybdenum Disulfide Nanoribbons

In a first, researchers developed an ultra-thin and ultra-sensitive photodetector with the highest light responsivity reported till date

Molybdenum disulphide (MoS2) nanoribbons have garnered significant attention due to their distinctive properties, which can be customized by adjusting their geometry. Building on this ability, a collaborative team of researchers has developed one of the world’s thinnest ultra-sensitive photodetector using a single MoS2 nanoribbon. The nano-thin device exhibits the highest light responsivity ever reported for single-nanoribbon photodetectors and can be easily transferred on plastic or paper.

In recent times, two-dimensional (2D) semiconductor materials have emerged as key components for various optoelectronic applications due to their high surface-to-volume ratios. Of these, molybdenum disulphide (MoS2) nanoribbons have become increasingly popular for their unique electrical, optical, and magnetic properties. These properties can be tuned by adjusting their dimensions with the help of methods like doping and strain. Doping involves intentionally adding impurities to materials, while strain refers to the deformation of a material's structure caused by an applied force.

However, despite the growing interest in using MoS2 for the development of photodetectors (or devices that convert light into electrical signals) and light-emitting diodes, very few photodetectors based on MoS2 nanoribbons have been reported. Moreover, these photodetectors have demonstrated modest performance.

In a new breakthrough, researchers from the Thin-Film Photovoltaics Group at the Technical University of Denmark (DTU) have developed a new highly sensitive photodetector based on a single MoS2 nanoribbon. The study was led by Dr. Stela Canulescu, Group Leader and Senior Researcher at the Technical University of Denmark’s Department of Electrical and Photonics Engineering. Dr. Canulescu explains, “We have developed one of the world's thinnest photodetectors, with a thickness of several nanometers – orders of magnitude smaller than the current standard silicon diodes and unbeatable mechanical flexibility. This nano-thin device could be used in smart devices, wearable electronics, and the Internet of Things.” This study was conducted by a collaborative team of researchers from Denmark, France, and the USA and was published in the journal Advanced Materials on 29 May 2023.

To this end, the researchers fabricated multilayered MoS2 nanoribbons through a vapor-liquid-solid approach. This involved a reaction between thin films of molybdenum oxides (which were grown via a method called pulsed laser deposition) and sodium fluoride in a sulfur-rich environment, yielding high-quality MoS2 nanoribbons. By controlling the growth parameters like temperature and film thickness, the length and height of the nanoribbons were adequately adjusted.

On being illuminated by visible light, the developed photodetector exhibited a remarkable responsivity of 8.72 x 102 amperes per watt at 532 nanometers and a specific detectivity of 2.5 x 1010 Jones at zero back-gate voltage. ¬¬The obtained values surpass all previously reported nanoribbon-based photodetectors in terms of performance.

The nanoribbons revealed distinct single-layer edges, forming a unique monolayer-multilayer junction. On performing Raman spectroscopy to study the material’s properties through their interaction with light, the researchers found that the splitting of light was attributed to different contributions from the single-layer edges and multilayer core. Nanoscale imaging further revealed that the single-layer edges emitted a light called “exciton” which appeared more blue-shifted compared to the isolated monolayers due to the internal strain caused by irregularities near the edges. Additionally, when exposed to light, these nanoribbons could emit a new light of a different color and higher intensity. “This remarkable property is what makes these nanoribbons ideal for use in photodetectors,” Dr. Canulescu adds, while talking about the results.

Elaborating further on the potential long-term applications of this study, Dr. Canulescu says, “From a broader perspective, this work presents a simple optoelectronic device architecture that can also be applied to other materials to achieve high performance in terms of responsivity and detectivity.” Overall, the study is a progressive step towards the development of highly crystalline multilayer MoS2 nanoribbons that have unique light detection capabilities. Going ahead, this could pave the way towards designing semiconductors with customizable geometries for a new generation of highly efficient optoelectronic devices.



Title of original paper

1Ganesh Ghimire, 1Rajesh Kumar Ulaganathan, 2Agnès Tempez, 3Oleksii Ilchenko, 4Raymond R. Unocic, 5Julian Heske, 1Denys I. Miakota, 5Cheng Xiang, 2Marc Chaigneau, 5Tim Booth, 5Peter Bøggild, 5Kristian S. Thygesen, 4David B. Geohegan, and 1Stela Canulescu

Molybdenum Disulfide Nanoribbons with Enhanced Edge Nonlinear Response and Photoresponsivity

Advanced Materials



1Department of Electrical and Photonics Engineering, Technical University of Denmark
2Horiba France SAS, France
3Department of Health Technology Nanoprobes, Technical University of Denmark
4Center for Nanophase Materials Sciences and Materials Science and Technology Division, Oak Ridge National Laboratory, USA
5Department of Physics, Technical University of Denmark

Image title: Photodetectors based on MoS2 nanoribbons show excellent light sensitivity
Image caption: An ultra-thin and ultra-sensitive photodetector based on a single MoS2 nanoribbon was developed by a collaborative team of researchers from Denmark, France, and the USA. It exhibits the highest light responsivity and detectivity values among reported single-nanoribbon-based photodetectors.
Credit: Dr. Stela Canulescu from the Technical University of Denmark (DTU)
License type: Original content