Background

Atomically-thin, layered, or 2D transition metal dichalcogenides (TMDs) have attracted attention both due to their remarkable electronic, optical, spin, and valley properties as well as their potential for diverse nanoelectronic, optoelectronic, sensing, and energy applications.

Carriers in these systems form tightly-bound neutral and charged excitons; and monolayer TMDs show strong photoluminescence peaks which result from a direct recombination of these excitons. Controlling the population and recombination energy of these excitons is extremely important for both fundamental and applied research, and hence, methods for direct manipulation of excitons is a topic of rapidly-growing interest.

Technology Overview

In this work Northeastern University researchers present a novel oxygen-induced switching between “non-radiative” and “radiative” exciton recombination in a family of 2D heterostructures: Bi2Se3 grown on arbitrary monolayer transition metal dichalcogenides (TMDs: WS₂, MoSe₂, and MoS₂).

This new class of 2D materials, which are on the nanoscale (only 2nm high), have a potential range of applications, including for use as oxygen sensors, data storage devices, and potentially as an identification tag to be used for incryption/anti-counterfitting of parts, drugs, etc. They are using known TMD’s (Monolayer transition metal dichalcogenides), but are combining those with a layer of a bismuth selenide (Bi2Se3) through a chemical vapor deposition process.

They are scalable in the x and y direction. When a laser spot or heat are applied in the presence of oxygen, the material begins to photoluminescence and change color. The photoluminescence intensity can be controllably tuned up or down by changing the treatment recipe (i.e, the amount of power vs the amount of oxygen vs the time duration of the treatment).

The team has demonstrated how the switching of exciton recombination pathways is affected by switching the ambient chemical environment under unchanged laser exposure. The signature photoluminescence (PL) peaks of TMDs, which are quenched in all as-grown heterostructures, appear distinctly when they are annealed in air, and re-quench when thermally annealed in N2 or Ar. This switching can also be accomplished locally, controllably, and reversibly using a low-power focused laser, while changing the environment from pure nitrogen to air. This allows for site-programmable 2D optical “Write-Read-Erase” devices and light-emitting pixels whose emission intensity could be precisely varied by a factor exceeding 200×, with a wide range of emission energy values in the visible (1.5eVph<2eV).

Benefits

Low-cost oxygen-sensors
Color-selectable , Site-programmable with sub micron resolution
Nanosized, atomically-thin (2nm: z‑direction), but scalable in the x‑y plane
Precise intensity-tunable photoluminescing pixels via controlled heating in an oxygen environment
Flexible high density information storage devices

Applications

2D photon or thermal calorimeter
Micro-cavity-lasers
Oxygen sensors
Ultra high-density optical information storage device with “Write-Read-Erase” capability
Non destructive corrosion testing: 2D oxygen-sensors between protective coatings on aircrafts and ships
Authenticity and part verification of heart pumps, pace makers, near sensors, aviation parts and national security system parts
High density data storage
Tagging parts for anticounterfeiting applications

Opportunity

Development partner
Commercial partner
Licensing

Family of 2D materials with Oxygen and Heat-Induced Submicron Site-Selectable Rapid "Write-Read-Erase" Capability, Enabling a 2D Oxygen-Sensor, a 2D Calorimeter, and Ultra High-Density Information Storage

IP Status

Seeking