AFOSR Funded Research Leads to a Quantum Dot Technological Breakthrough

  • Published
  • By Erin Crawley
  • AFOSR Public Affairs (Quantech)
ARLINGTON, Va. --  Using Air Force Office of Scientific Research basic research funding, through the Asian Office of Aerospace Research & Development (AOARD), a team of scientists from Thailand are the first in their field to successfully demonstrate solid experimental results on the physical utilization of quantum dots for photovoltaic operations.

AOARD is the international directorate of AFOSR, supporting AFOSR in Asia. AOARD plays a key role in managing international basic research collaborative efforts by providing liaisons to the scientific and engineering community who encourage open communication between Air Force scientists and engineers and their counterparts within their areas of responsibility.

The Thailand research team is from the department of electrical engineering, Chulalongkorn University, Bangkok. According to the project's principal investigator, Professor Somsak Panyakeow, this scientific breakthrough could result in significant advancements for the Air Force and the community at large. "Quantum dot solar cells using III-V compound semiconductors give high energy conversion efficiency," said Panyakeow. "High efficiency means smaller cell area for a given PV [photovoltaic] output. Therefore, weight-to-power ratio is reduced and would be important to the Air Force both for terrestrial and space applications," said Panyakeow.

Prof. Panyakeow first presented the results May 12 at the 2006 Institute of Electrical and Electronics Engineers World Conference on Photovoltaic Energy Conversion held May 12 - 18 in Waikoloa, Hawaii. His presentation was entitled, "Improvement of PV Performance by Using Multi-Stacked High Density InAs Quantum Molecules."

To obtain their results, the research team used Molecular Beam Epitaxy (MBE), a process using organic materials in a high-vacuum environment. This was achieved atomic layer by atomic layer.

Scientific and military communities are interested in quantum dots because they have the ability to capture light much more efficiently than other materials, and convert it to an electrical signal. Quantum dots can be easily tuned to specific wavelengths ranging from visible to infrared for light emission or absorption. Additionally, the interaction of quantum dots with radiation at all frequencies of visible, infrared, and ultraviolet light also make the dots an ideal material for use in detection of microwave radiation (i.e. sensors and detectors), and for very efficient low power electric lighting, said Dr. Donald Silversmith, program manager, AFOSR's Physics and Electronics Directorate.

"There have been a number of simulations of this potential nanotechnology application along with some partial fabrication activities and fabrication attempts, but this work represents the first full working demonstration of this concept," said Silversmith. Dr. Silversmith attended Dr. Panyakeow's May 12 presentation, and is interested in the potential applications this technology may have regarding various sensors.

"The big deal about this research is that this team has shown that quantum dots photovoltaics can work. The team did it physically rather than theoretically," said Silversmith. "They actually made quantum dot structures specifically for photovoltaic applications and built the photo cells and measured them. Other people have been doing various pieces of this with not very conclusive results. What makes this work interesting is that it's the first, in my mind, conclusive results in an integrated sense that really works. This approach may lead to very effective broadband ultraviolet, visible, and infrared sensors and detectors," added Silversmith.

Another important aspect of this breakthrough is the international collaborative effort spawned by the foresight of Dr. Brett Pokines, liaison scientist at AOARD in Tokyo. Dr. Pokines had the prescience to identify the potential benefits of Panyakeow's research to the Air Force and made, what turned out to be a significant investment on the Air Force's behalf. "Dr. Panyakeow and his team are an impressive and established group performing world-class Air Force relevant research that is impacting the science community," expressed Dr. Pokines.

Prof. Panyakeow greatly appreciates the AOARD support for his team's research. "Doing frontier research always needs dinational collaboration is very important. The financial support we receive from AOARD provides us with the seed money which we can leverage to gain more support from national granting agencies [in Thailand], such as the Thai Nanotechnology Center," said Prof. Panyakeow.

Through programs such as quantum dots, AFOSR continues to expand the horizon of scientific knowledge through its leadership and management of the Air Force's basic research program. As a vital component of the Air Force Research Laboratory, AFOSR supports Air Force's mission of control and maximum utilization of air and space. Many of the technological breakthroughs enjoyed by millions today, such as lasers, GPS, and the computer mouse trace their scientific roots to research first funded by AFOSR.