What you carry in your hand or pocket is powered by semiconductor technology. The display of your phone shines bright because of light-emitting diodes (LEDs). Your phone camera operates by converting light into electricity. So are so many other optoelectronic devices powered by semiconductors such as solar cells, photodetectors, and lasers.
Optoelectronic devices convert light into electricity and vice versa. They are powered by semiconductors, making them a very important and necessary technology. Although three-dimensional (3D) semiconductors are preferred and continue to dominate the market, two-dimensional (2D) semiconductors have emerged as promising alternatives.
Since the successful mechanical exfoliation of monolayer graphene (graphene is a two-dimensional sheet of carbon atoms, known for its advantageous properties such as being strong, lightweight, and flexible, thus called a “wonder material”), and the synthesis of phase-pure perovskite (perovskites are crystalline materials known for their high flexibility and efficiency) quantum dots, low-dimensional semiconductors have been recognized for their disruptive potential.
Focusing on 2D materials, there are three materials used in optoelectronic devices:
- 2D Transition Metal Dichalcogenides (TMDs):
These are a combination of transition metals (molybdenum, tungsten) with chalcogens (sulphur, selenium, tellurium), represented by the formula MX2, where ‘M’ depicts a transition metal, and ‘X’ depicts a chalcogen. These materials are unique for their thickness-dependent properties, making them ideal for high-end electronics, optoelectronics, and flexible devices.
- 2D Perovskites:
These are layered hybrid organic-inorganic materials, structured as thin 2D sheets. They are ideal for durable optoelectronics such as solar cells, LEDs, and photodetectors because of their advantageous properties, such as higher moisture, thermal, and photostability.
- 2D MOF (metal-organic framework):
It is a crystalline, porous material consisting of metal nodes. They are thin, sheet-like structures with a high surface area and atomic-scale thickness. They have high structural flexibility and tunable electrical properties.
In these materials, optical responses are governed by tightly bound electron-hole pairs, known as excitons. Electrons are negatively charged particles in an atom, and a hole is what is left when an electron exits its place. Holes are positively charged.
An exciton can be visualized as a “dance pair”. The electron and hole are the dance partners, which move together briefly. Finally, the electron and hole recombine to release energy in the form of light.
Another aspect to be focused upon is the light-matter coupling (coupling refers to the transfer of energy or interaction between two physical systems, like light and matter), or the combination of excitons and polaritons. Polaritons are a hybrid state of light and matter that forms in the presence of strong coupling.
Previous reviews have focused on exciton-based optoelectronic devices, while those on strong light-matter coupling (excitons-polaritons) have emphasized fundamental aspects, often with limited attention to device applications.
In this review, the authors have presented recent progress in 2D optoelectronic devices based on excitons and strong light-matter coupling (polaritons), emphasizing their unique advantages.
Also discussed are emerging polaritonic devices involving interactions between light and quasiparticles such as excitons, plasmons, or magnons (quasiparticles are emergent particles that arise inside materials when the particles interact with each other). Recent advancements in using strong coupling for photodetectors, LEDs, and on-chip devices have also been covered in this review.
The authors not only summarize device demonstrations but also extract design rules for achieving high power density, low threshold, or spectral tunability under strong coupling. These devices can pave the way for all-2D-based integrated photonic circuits, flexible light emitters, and solar cells.
Finally, the critical role of electron microscopy in probing strong light-matter interactions at atomic resolution has also been highlighted.
By outlining present challenges and future directions, this review provides a roadmap for next-generation exciton- and polariton-based technologies.
In this review, the authors came to the conclusion that TMDs and 2D perovskites are promising 2D materials for use in solar cells, lasers, photodetectors, and photovoltaics. The results reflect the possibility of device fabrication without dealing with the complexity of 2D material synthesis and fabrication.
The following are the authors of this paper:
- Dr. Janani Archana K, from Low-dimensional Semiconductors Lab, Department of Metallurgical and Materials Engineering, Indian Institute of Technology (IIT) Madras, Chennai, India.
Also from this department are: Dr. Kumar Shwetabh, Mr. Reyas Ali, Mr. Ramji Velayutham, Mr. Koustav Das, Mr. Abhishek Mondal, and Prof. Surendra B. Anantharaman. Prof. Surendra B. Anantharaman is also affiliated with the Center for 2D Materials Research and Innovation, IIT Madras, Chennai, India, and the School of Interdisciplinary Studies (SIDiS), IIT Madras, Chennai, India.
- Prof. Prashant Kumar from the School of Materials Science and Engineering, Nanyang Technological University, Singapore.
Prof. Arka Majumdar from the Departments of Electrical and Computer Engineering and Physics at the University of Washington, USA acknowledged the significance of the review done by the authors with the following comments: “Strong light-matter coupling in low-dimensional materials continues to open rich physics and novel device concepts. While much of the foundational work on polaritons has focused on fundamental optical phenomena, band engineering, or exotic quantum phases like polariton lasing, translating these hybrid states into practical technologies remains a vital frontier. This comprehensive review article offers a timely and necessary shift in focus toward device applications. By thoroughly synthesizing how exciton-polaritons, plasmon-polaritons, and magnon-polaritons enhance key figures of merit in optoelectronic architectures—including photodetectors, solar cells, and light-emitting diodes—the authors bridge fundamental polariton dynamics with practical implementation. It serves as an excellent, clear entry point for newcomers and researchers looking to rapidly get up to speed on the applied potential of 2D polaritonic devices.”
Article by Akshay Anantharaman
Click here for the original link to the paper
