Organic light-emitting diode technologies (OLEDs), a key technological feature in the display of many models of mobile phones and televisions already provide great image quality and high-resolution. But are they as efficient as they can be? Inspired by methods used in liquid-crystal technology, Kent State University researchers in the College of Arts and Sciences have developed new ways to improve OLED efficiency even more. 

Their new approach is discussed in their recent article “Tuning charge carrier transport and optical birefringence in liquid-crystalline thin films: A new design space for organic light-emitting diodes” which was recently published online in Scientific Reports at: www.nature.com/articles/s41598-018-19157-9

“We were able to show that being able to control the orientation or alignment of molecules inside the organic film has the potential to improve the efficiency of organic light-emitting diodes used in the latest cell phones or TV sets,” Dr. Björn Lüssem, assistant professor in the Department of Physics, said.

Some of the advantages of this new approach include low voltage operation, high power efficiency, reduced power consumption, enhanced charge transport in organic semiconductors and the ability to tune the light propagation in OLEDs. In their study, the electrical and optical characteristics of the devices were measured, including luminance, luminous efficiencies and lifetime of OLEDs.

Lüssem led a team of scientists including Postdoctoral Fellow Chang-Min Keum, Ph.D., in the concept design, device fabrication, characterization, and data analysis. Co-authors of this article included Kent State Physics doctoral students Shiyi Liu, Akram Al-Shadeedi, and Vikash Kaphle. Others that provided contributions to the project included Kent State Professors Scott D. Bunge, Ph.D., and Robert J. Twieg, Ph.D., in the Department of Chemistry and Biochemistry, and Antal Jakli, Ph.D., of the Liquid Crystal Institute.

In addition, Michiel Koen Callens and Kristiaan Neyts of the Department of Electronics and Information Systems at Ghent University, in Belgium; Lu Han and Hongping Zhao of Case Western Reserve University (now at The Ohio State University); and Malte C. Gather of the University of St. Andrews also contributed to the project and publication.