Issue Date: March 2, 2015
ACS Award In The Chemistry Of Materials
Sponsored by E. I. du Pont de Nemours & Co.
In less than a decade, Mark E. Thompson’s work in synthesizing materials for organic light-emitting diodes (OLEDs) has gone from lab bench to smartphone screens.
Now a professor of chemistry at the University of Southern California, Thompson entered the University of California, Berkeley, as an undergraduate with the intention of becoming a high school chemistry teacher like his father. But one day, as he was explaining quantum mechanics to his dad, Thompson realized he didn’t want to stop at a bachelor’s degree. He wanted to continue exploring and expanding his knowledge. “That’s why I went to graduate school, and that’s why I wound up in the job that I’m in,” he says.
At California Institute of Technology, Thompson did his graduate research in organometallic catalysis and received a Ph.D. in inorganic chemistry in 1985. “Then I did a postdoc thinking I was going to do something as dramatic as shift from early-transition-metal chemistry to late-transition-metal chemistry,” he says. Instead, while working at Oxford University with Malcolm L. H. Green, his focus shifted more dramatically toward the burgeoning field of materials chemistry.
Thompson brought that interest to Princeton University, where he started as an assistant professor in 1987. There, he began a long-term collaboration with physicist Stephen R. Forrest, then also at Princeton and now a professor at the University of Michigan, Ann Arbor. Forrest was interested in testing new materials for OLEDs—materials that Thompson had the ability to synthesize.
Thompson and Forrest developed a systematic approach in which they would decide what they wanted to learn and what materials parameter they’d need to vary to get an answer. Thompson’s group would synthesize and purify the compounds, and Forrest’s group would use them to make devices.
That approach led to their biggest contribution to the field of OLEDs. In the 1990s, researchers understood that OLED materials generate both singlet and triplet excited states in response to the application of electricity. But devices at the time only made use of the singlet excitons, which limited their efficiency at converting electricity to light. “We needed to find things that emit from triplet excited states very efficiently, and that’s where my background in inorganic chemistry came in handy,” says Thompson, who is now 57. He moved to USC in 1995, but the fruitful collaboration continued.
In 1998, Thompson and Forrest demonstrated that a platinum porphyrin dye could release energy transferred from both singlet and triplet excitons, generating red light through fluorescence and phosphorescence (Nature 1998, DOI: 10.1038/25954). They then quadrupled the OLED efficiency to nearly 100% with an organometallic iridium compound (Nature 2000, DOI: 10.1038/35001541). From there, the researchers extended the work to OLEDs that glowed in a rainbow of colors and into the ultraviolet and near-infrared.
Samsung licensed the technology from Universal Display Corp., the company formed to develop the OLED research coming from the team’s labs. Now, cousins of the iridium compounds synthesized by Thompson can be found in Samsung’s popular Galaxy S4 and S5 smartphones.
“His is the first real application of organic electronics,” according to Fred Wudl, professor of chemistry and materials at UC Santa Barbara, “and without Thompson’s work, OLEDs would still be a laboratory curiosity.”
Thompson will present his award address before the Division of Inorganic Chemistry.
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