Non-doped Phosphorescent Organic LEDs: A New Way to Simplify Device Fabrication

Phosphorescent Organic LEDs (PHOLEDs) can achieve high efficiency by converting 100% of the injected electrons into photons, holding great potential for lighting and display applications. Because common phosphorescent materials show severe concentration quenching effect in the neat form caused by strong aggregation of triplet excitons, a guest"“host doping method is widely used in today's PHOLEDs. However, doping is complicated in device fabrication and consumes time and materials, thus increasing fabrication cost. Furthermore, need of high band-gap hosts, different aging rates between host and guest and device reproducibility are other problems of this method. Non-doped PHOLEDs can resolve these issues, but their efficiency is very low. In this seminar, a method to solve this problem is reported. We introduce a new type of Pt metal complexes with square-planar molecular structure. Contrary to common phosphors, these materials show a near unity photoluminescence quantum yield, high electron mobility and reduced triplet quenching effect in the neat form. Accordingly, non-doped red, orange, yellow and white PHOLEDs with very high efficiencies that even outperform today's state-of-the-art doped PHOLEDs are realized. This work helps reconsider neat phosphorescent materials and provides a new way to simply device fabrication and reduce cost.
Dr. Qi Wang earned his Ph.D. degree in Organic Electronics from the Chinese Academy of Science in 2009. From 2009 to 2015, he has worked at the University of Texas at Dallas, Xi'an Jiaotong University, South Dakota State University and Atom Nanoelectronics Inc, respectively. Since 2004, he has been working on organic optoelectronic devices including LEDs, solar cells, transistors and displays. Dr. Wang has published over 30 paper, 13 with Impact Factor >10. Among his papers, 4 are selected as cover story; and 5 are selected as Highly Cited Papers by ESI. His papers have received over 2700 citations from peers with 7 papers receiving > 140 citations. His works have also been reported by prestigious media including: New Scientist, Nature China, American Institute of Physics, ScienceDaily. US Department of Energy (DOE) reported one of his works as "significant achievements in 2010." Dr. Wang received "Tengfei" Distinguished Professor award (2013), First Prize of Technology Development in Jilin Province, China (2012), First Prize of Natural Science in Jilin Province, China (2011), Outstanding Doctoral Thesis, CAS (2011), and President Award for Excellence, CAS (2009).