The commercialization of next-generation high-efficiency optical energy conversion technology is expected to be accelerated thanks to the research results of domestic researchers.
KAIST announced on the 12th that a joint research team led by Professor Jung-Young Park of the Department of Chemistry at KAIST and Professor Moon-Sang Lee of the Department of Materials Science and Engineering at Inha University identified a mechanism that amplifies the flow of ‘hot holes’ and enhances photocurrent through real-time local current distribution mapping.
Plasmonic hot carriers, which are momentarily generated when light hits metal nanostructures, are important mediators that convert optical energy into high value-added energy sources such as electrical and chemical energy.
Among them, hot holes amplify the efficiency of photoelectrochemical reactions but have been difficult to apply practically because they thermally dissipate within an ultrashort time scale of picoseconds (one trillionth of a second).
In response, the joint research team designed a nano-diode structure by placing a metal nanomesh on a special semiconductor material (p-type gallium nitride) substrate and devised a method to promote hot hole extraction on the substrate surface.
As a result, the gallium nitride substrate aligned with the hot hole extraction direction showed about twice the amplification effect of hot hole flow compared to substrates oriented in other directions.
The joint research team also analyzed the flow of hot holes in real time at the nanometer scale (one hundred thousandth the thickness of a human hair) using a photocurrent mapping system based on photoconductive atomic force microscopy.
During this process, the team confirmed that the flow of hot holes is strongly activated mainly at ‘hot spots’ where light is locally concentrated on the gold nanomesh, but changing the growth direction of the gallium nitride substrate activates hot hole flow even in areas outside the hot spots.
Through this, they found an efficient method to convert light into electrical and chemical energy, opening possibilities to advance next-generation solar cells, photocatalysts, and hydrogen production technologies, according to the joint research team.
Professor Jung-Young Park of KAIST said, “The joint research team has, for the first time, been able to control the flow of hot holes using the nano-diode technique,” adding, “We expect this to make innovative contributions to various optoelectronic devices and photocatalyst applications.”
Meanwhile, this research was conducted with support from the National Research Foundation of Korea (NRF). Dr. Hyun-Hwa Lee of KAIST’s Department of Chemistry and postdoctoral researcher Dr. Yoo-Jin Park of the Department of Chemical Engineering at the University of Texas at Austin are the first authors, and Professor Moon-Sang Lee of Inha University’s Department of Materials Science and Engineering and Professor Jung-Young Park of KAIST’s Department of Chemistry participated as co-corresponding authors. The research results were published online on the 7th in the international journal Science Advances.
© The Asia Business Daily(www.asiae.co.kr). All rights reserved.
