Investigating the surface chemistry of quantum dots: Implications for renewable energy

Svetlana Kilina, assistant professor of chemistry and biochemistry, has received a $750,000, five-year award from the U.S. Department of Energy Office of Science Early Career Research Program. Funding will be used to conduct research outlined in Kilina's proposal titled "Modeling of Photoexcited Process at Interfaces of Functionalized Quantum Dots."

Kilina's research occurs at the intersection of renewable energy, high-performance computing, nanotechnology and chemistry. Quantum dots are nanocrystals discovered by scientists in the 1980s. Ranging in size from two to 10 nanometers, billions of them could fit on the head of a pin. Their tiny sizes belie the Herculean impact they could make in semiconductors and energy. Kilina's work centers on new-generation solar cells and fuel cells using quantum-dot-based materials.

Materials at the nanoscale level behave differently than at larger scales. Energized quantum dots absorb and emit light. The color of the light depends on the size of the dot. In addition, one quant of light can generate more than two carriers of electric current – two electrons-hole pairs instead of one – in quantum dots. As a result, quantum dots could convert energy to light or vice versa more efficiently than conventional energy materials based on bulk semiconductors such as silicon. That makes quantum dots very promising materials for solar cells and other energy applications.

"One of the main obstacles in the synthesis of quantum dots is the controllable chemistry of the quantum dot surface," Kilina said. "Due to their nanosize, the dots are extremely chemically reactive, and different organic molecules from solvent/air environment interact with the surface of the quantum dot during and after synthesis. These molecules cover the surface of the quantum dot like a shell, influencing its optical and electronic properties."

Kilina uses supercomputers to conduct computer-simulated experiments, and investigate and advance her research in this field. Her goal is to generate theoretical insights to the surface chemistry of quantum dots, which are critical to design efficient quantum-dot-based materials for solar energy conversion and lighting applications.

To apply her model and algorithmic methods, Kilina's research group uses supercomputers at the NDSU Center for Computationally Assisted Science and Technology, in addition to Department of Energy and Los Alamos National Laboratory leadership-class, high-performance computing facilities. The combination of NDSU supercomputing and government facilities substantially reduces the amount of time needed for the massive calculations used in this research.

"Dr. Kilina's research aims to gain fundamental understanding of nanomaterials at the molecular and electronic level," said Greg Cook, chair of NDSU's Department of Chemistry and Biochemistry. "Insights gained from this research will enable the progression of solar energy technology to help solve the world's energy challenges. The Department of Energy award recognizes Dr. Kilina's unique expertise in the area of theoretical modeling of these materials critical for the future."

Kilina's research addresses fundamental questions of modern materials science that affect the design and manufacture of new-generation energy conversion devices. To design and manufacture such devices requires developing new multi-functional materials with controllable properties. It is anticipated that the acquired theoretical knowledge gained from the research at NDSU will help better explain and interpret experimental data and could facilitate rational design of new nanostructures with desired optical, transport and light harvesting properties that are fundamental to a myriad of clean energy technologies.

More information:
www.ndsu.edu/chemistry/people/faculty/kilina.html

Provided by North Dakota State University