Lights, Cameras, Copper

Professor Thomas Brown of the Chemistry Department at SUNY Oswego gave a presentation on February 20th of copper’s light-emitting nature and how this can make copper a less expensive alternative to noble metals in display technologies and solid-state lighting in the near future. Through his presentation, Brown shows us the research that he and his graduate students have been conducting for over two years.

As a student at the University of California Davis, Brown found a passion for inorganic/organometallic chemistry. Unsure with what he wanted to pursue a career in at this point, Brown decided to go to graduate school at the University of Nevada at Reno to further his education. Here, he had met a professor who had done research on inorganic and organometallic chemistry. Brown was inspired by this professor and wanted to spend his life teaching what he studies and experimenting on inorganic compounds with those that he teaches.

After coming to SUNY Oswego, Professor Brown became extremely passionate about a chemistry project that was going to teach his undergraduate and graduate students a variety of skills that they could take with them elsewhere beyond college. Over two years ago, Professor Brown began his research on controlling the coordination of metal which can induce metallic interactions, emitting different colors. Brown has been working extensively with graduate students inside and outside of the lab, figuring out how much light can be emitted, where it can be emitted, and what colors can be emitted. This specific experiment is accredited to a seminal paper released approximately twenty years ago by the Macmillan Group, which explained that taking two acceptor ligands and putting them on copper while shining UV light on to the copper, emits light in colors. This seminal paper helped this research field take off.

Brown’s specific research is based off changing and tuning the gap between the Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO). He experiments on raising and lowering the HOMO and LUMO levels based on the number of atoms he connects to the metal which alters the colors that are emitted. Changing the gap of energy between these orbitals dictates how much light is emitted off of the copper and changes the wavelengths which control light and the specific color of the light.

When conducting copper light-emitting experiments, Brown makes sure to keep green chemistry in his head at all times. Brown said the goal of green chemistry is to mitigate waste and not use halogen solids, but instead use benign solids. There are multiple principals for green chemistry. Two of the main principal’s are to one, use safer chemicals and two, prevent waste formation (Anastas, Warner, 1998). Brown argued that people should not use halogen solids but there is a tradeoff since there are benefits that can come from it. However, Brown has put some thoughts into starting a project on depleted uranium. There’s a lot of upside in using depleted uranium since it follows the green chemistry guideline, Brown just needs to figure a way for the Nuclear power plant to send their radioactive waste to SUNY Oswego. Using copper still follows green chemistry guidelines because there is an abundance of it and it is less expensive compared to the noble metals that are in our laptops and smartphones.

Brown recognizes that using this material over the noble metals currently being used will cut down the cost of production which could lead to a cut down in prices. Brown says that his end goal would be to put the copper into actual devices like smartphones and computer screens. He mentions that ruthenium and iridium are a few of the expensive noble metals currently in our electronic devices that could be removed for an alternative material. Not only does Brown say that noble metals are expensive, but they are also more toxic than copper. To start his project and because he is a small molecule chemist, Brown says that he would need to collaborate with a material scientist to make films of the material which then he would be able to work them into electroluminescence devices.

Further Reading

Chen, T. Q., Liang, T., Zhang, P., & MacMillan, D. W. (2018, June 01). A radical approach to the copper oxidative addition problem: Trifluoromethylation of bromoarenes. Retrieved from http://science.sciencemag.org/content/360/6392/1010

4.1. Principles of Green Chemistry. (n.d.). Retrieved from https://www.e-education.psu.edu/eme807/node/534

Borths, C. (2001). Ligand Accelerated Catalysis(Rep.). Retrieved from http://chemlabs.princeton.edu/macmillan/wp-content/uploads/sites/6/borths-LAC.pdf

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