Using a layer of molybdenum disulfide less than 1nm thick, researchers in Rice University's Thomann lab were able to design a system that absorbed more than 35% of incident light in the 400nm to 700nm wavelength range. Image: Thomann Group/Rice University.
Using a layer of molybdenum disulfide less than 1nm thick, researchers in Rice University's Thomann lab were able to design a system that absorbed more than 35% of incident light in the 400nm to 700nm wavelength range. Image: Thomann Group/Rice University.

Mechanics know molybdenum disulfide (MoS2) as a useful lubricant in aircraft and motorcycle engines and in the universal joints of trucks and automobiles. Rice University engineering researcher Isabell Thomann knows it as a remarkable light-absorbent semiconductor that holds promise for the development of energy-efficient optoelectronic and photocatalytic devices.

"Basically, we want to understand how much light can be confined in an atomically-thin semiconductor monolayer of MoS2," said Thomann, assistant professor of electrical and computer engineering, materials science and nanoengineering, and chemistry. "By using simple strategies, we were able to absorb 35–37% of the incident light in the 400nm to 700nm wavelength range, in a layer that is only 0.7nm thick."

Thomann and Rice graduate students Shah Mohammad Bahauddin and Hossein Robatjazi report their findings in a paper in ACS Photonics. This research has many potential applications, including the development of efficient and inexpensive photovoltaic solar panels.

"Squeezing light into these extremely thin layers and extracting the generated charge carriers is an important problem in the field of two-dimensional (2D) materials," Thomann explained. "That's because monolayers of 2D materials have different electronic and catalytic properties from their bulk or multilayer counterparts."

Thomann and her team used a combination of numerical simulations, analytical models and experimental optical characterizations to develop a light-absorbing system based on MoS2. Using three-dimensional electromagnetic simulations, they found that light absorption was enhanced 5.9 times in their system compared with using MoS2 on a sapphire substrate.

"If light absorption in these materials was perfect, we'd be able to create all sorts of energy-efficient optoelectronic and photocatalytic devices. That's the problem we're trying to solve," Thomann said.

She is pleased with her lab's progress so far but concedes that much work remains to be done. "The goal, of course, is 100% absorption, and we're not there yet."

This story is adapted from material from Rice University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.