Group Goals: Energy Conversion Materials and Our Environment
As fossil fuel energy sources become increasingly scarce and the burning of coal and petroleum is curbed to mitigate climate change, the impetus to produce energy from sunlight and alternative energy sources, as well as to utilize energy more efficiently continues to grow. Finding low-cost materials and strategies to fabricate solar cells and other alternative energy sources constitutes an important scientific challenge facing our generation. The mission of our research team is to make the world a better place by developing new, cost-effective ways to convert sunlight into electrical energy, or to utilize electrical energy more efficiently by development of new materials, optoelectronic devices and batteries.
Solar energy is practically unlimited and can be harvested with minimal pollution or environmental impact using solar cells. Thanks to the efforts of researchers around the globe to help reduce the cost and improve the efficiency of solar cells, as well as efforts by governments and citizens around the world to support the adoption of solar cells as an energy source, solar cells are now the fastest growing source of electricity and account for more than 1% of electricity generated worldwide. Continued efforts to develop low-cost and economical solar technologies will cause this fraction of energy to keep growing, reducing mankind's need to burn fossil fuels which release greenhouse gasses and pollute the environment.
As more energy comes from renewable sources like solar and wind, there is a problem that times of peak energy production (when it is sunny or windy) do not coincide with times of peak energy consumption (when people turn on lights, cook, shower, etc.). Therefore, as renewable energy sources are used more ane more, a growing problem is how to store energy which is produced from intermittent energy sources and distribute it when it is needed. Redox Flow Batteries are a type of battery that use electrochemically active molecules to store energy.
Researchers Needed!
Undergraduate, MS and PhD students are currently needed to help with research related to (1) Redox flow batteries and (2) Electronic noses. Please contact Dr. Walker (walker@khu.ac.kr) if you're interested!
Our Lab and Research
Equipment in our laboratory used to make organic semiconductors, hybrid semiconductors, chromophores, fluorophores, air-sensitive materials and semiconducting devices like solar cells, transistors, light-emitting solar cells, light-emitting transistors and more. More details can be found by clicking on our research and facilities links. Occasionally, our work is featured on the cover of journals like Advanced Functional Materials :
Schlenk Line
Glovebox
EQE
(moved to University of Seoul)
Integrating Sphere
Redox Flow Battery
Redox Flow Battery (in use)
Organic Light-Emitting Diode (OLED)
How do Semiconducting Devices Like Solar Cells, LEDs, Transistors and Light-Emitting Solar Cells Work?
Semiconductor band theory goes a long way to explain how different types of semiconducting devices operate. Determining the energies of electronic states (energy bands) in semiconducting materials allows us to predict which way positive and negative charges will move in order to achieve the most energetically stable state and which pathway imposes the lowest energy barrier. Solid materials contain electronic bands that are either filled with electrons or are empty. The filled energy band with the highest energy is called the valence band (VB) and the unfilled energy band with the lowest energy is called the conduction band (CB).
Learn more here.
Links
Best research cell efficiencies, updated by the National Renewable Energy Laboratory in Golden Colorado.
Web of Science. An intuitive and powerful way to search the literature.
Google translate. Helpful tool for going between English / Korean.
Twitter: @Prof_B_Walker
A few of our Collaborators at Other Departments / Universities:
Prof. Jang Hyuk Kwon
Department of Information Display