IISER Bhopal study could pave way for development of advanced optoelectronic devices

IISER Bhopal researchers are conducting research on properties of transition metal dichalcogenides (TMDs), a class of advanced two-dimensional materials.

Researchers of Indian Institute of Science Education and Research (IISER) Bhopal are exploring the properties of transition metal dichalcogenides (TMDs), a class of advanced two-dimensional materials with unique electrical, optical, and mechanical properties. The research on one kind of TMDs – Molybdenum Disulphide (MoS2) nanosheets, could pave the way for the development of advanced optoelectronic devices such as phototransistors, light detectors, light-emitting diodes (LEDs) and solar cells. 

The findings of the research have recently been published in The Journal of Physical Chemistry C, and Surface and Interface Analysis. The research is led by KV Adarsh, professor, Department of Physics, IISER Bhopal, and his research scholars. 

TMDs such as MoS2 nanosheets are semiconducting 2D layered materials, and their thickness-dependent band gap makes them a potential material for optoelectronic devices. Previous research has reported the existence of free carriers and excitons, which are particles produced when an electron is excited by light. These carriers play a vital role in electronic and optoelectronic applications.  

Scientists have conducted several studies to understand how these carriers behave when generated by light. These studies have shown that various factors, such as defects, free carriers, lattice heating, and sample processing, can affect carrier dynamics. However, distinguishing between them has been challenging. 

KV Adarsh and his PhD and other co-authors from BARC, Mumbai used an advanced technique called femtosecond transient absorption spectroscopy to study how light interacts with few layer MoS2 nanosheets. Their work found clear evidence of two types of charge particles – excitons and free carriers, that behave differently based on the amount of energy used to excite them. 

The researchers found that high-energy light produces excitons and free carriers, but the excitons disappeared quickly due to defects. Free carriers, on the other hand, lingered for up to a nanosecond (a hundred thousandth of a second). Low-energy light only produced excitons, which disappeared quickly. 

“Our systematic studies in few layer MoS2 nanosheets reveal crucial information on the unexplored domain of excitons and free carriers’ recombination in the presence of defects for several optoelectronic applications, said KV Adarsh. 

Read more: 

• JEE Main April 11 Shift 1 paper analysis: Students find paper moderate 
• JEE Main April 13 admit card released on jeemain.nta.nic.in 
• CUET 2023: JMI Extends Deadline to Apply for UG Courses till April 12