Malika Jeffries-EL is on a mission to find a better blue. Her medium is not paint or pastels but organic light-emitting materials found in cell phones, TVs, and other electronic devices.
Hometown: Brooklyn, New York
Education: BA, Wellesley College, 1996; MPhil, 1999, and PhD, 2002, the George Washington University
Current position: Professor of chemistry and associate dean of the Graduate School of Arts and Sciences, Boston University
First job: Cashier, Burger King
Best professional advice she’s received: Bring your authentic self to the workplace. Don’t feel compelled to change to fit in; make them adapt.
In her lab at Boston University, she and her team develop organic semiconductor materials that enable flexible, lightweight, environmentally friendly electronics. “Organic semiconductors combine the electronic properties of conventional semiconductors like silicon with the ease of processing of organic materials like polymers,” Jeffries-EL says.
While traditional semiconductors are based on elements such as silicon and germanium, organic semiconductors are made from carbon-based molecules that can be synthesized in a lab, allowing chemists like Jeffries-EL to engineer their atomic structure and shape building blocks for new materials.
Bendy and versatile, these organic materials can be printed onto thin surfaces and packaged inside compact devices at relatively low cost. “These are the materials that are driving almost all the cool technology everyone is so dependent on these days,” Jeffries-EL says.
Organic semiconductors are found in biosensors that measure blood glucose. They’re found in paper-based thin-film transistors made with aerosol jet printers. In organic light-emitting diodes (OLEDs), they produce bright, high-contrast colors in tablets, smartphones, and flat-screen displays.
Though ubiquitous, OLEDs have an Achilles’ heel. “You can usually generate every color combination you need if you have the core three primaries: red, blue, and green,” Jeffries-EL says. But OLEDs tend to suffer from short lifetimes because they are susceptible to damage from exposure to oxygen, moisture, and high temperatures. Blue OLEDs are the least stable.
Jeffries-EL and her research team have developed semiconducting molecules that emit deep-blue light while maintaining thermal stability, which increases a device’s life span, as OLEDs can degrade when they heat up.
The chemist also works on novel materials for photovoltaics. Today, most solar cells are made with crystalline silicon and are usually rigid and bulky, Jeffries-EL says. “Organics are thinner; they’re lightweight,” she says. “They can be made on flexible devices. So you can make curves and bends in a way that you can’t with the silicon.”
Flexibility presents enormous potential, says Gregory Welch, a chemist at the University of Calgary who prints small-molecule semiconductors. “You can print these organic materials, just like classical inks,” Welch says. In the coming years, he says, “it’s easy to see printing miles of solar panels at cents per watt.”
Like the polymers in her lab, Jeffries-EL stays flexible at work, Welch says. “What Malika has been able to do, very elegantly, is she’s developed a tool kit where she can make new materials, understand their structures, and then determine all their properties,” he says. “By doing that, she can really fit the function.”
The two primary areas of research for these materials now focus on conjugated small molecules and polymers, which Jeffries-EL has engineered into unique structures for more than a decade.
“While her materials have found some application in devices, it is her contributions to developing new examples of conjugated materials that make her stand out,” says Seth Rasmussen, a chemist-historian at North Dakota State University who has mentored Jeffries-EL.
Whether she’s creating new polymers for solar cells or small molecules to make a better blue-emitting OLED, Jeffries-EL thrives in the creative environment of her lab. “I love what I do scientifically because it’s so interdisciplinary,” she says. “I think there are lots of exciting opportunities at this interface between chemistry and materials.”