Report title: new generation of high efficiency organic luminescent materials
Guest: Professor Yang Bing, director of State Key Laboratory of supramolecular structure and materials, Jilin University
Time and place: 10:00-11:00 am, May 21
Abstract: the nature of excited states determines the luminescence properties.Due to the very small energy level difference between singlet and triplet states, the charge transfer (CT) excited states can greatly promote the channeling between reverse systems and improve the utilization of triplet excitons in organic electroluminescent devices.However, the photoluminescence (PL) efficiency of CT state is usually low.Our strategy is to combine the locally excited (LE) state with the CT state to form the hybrid local charge transfer (hlct) excited state, which can ensure the PL efficiency and high exciton utilization at the same time.For example, in triphenylamine phenanthrimidazole system, equal hlct states are obtained, and high efficiency undoped blue fluorescent devices (EQE = 7.8%, exciton utilization = 97%) are realized.This intramolecular hlct state composition can be precisely adjusted by D-A structural parameters (such as electron donor and acceptor capacity, D-A distance, connection, torsion angle, etc.).Based on the new concept of hlct state, a series of high performance panchromatic organic electroluminescent devices were designed and fabricated.Further extended to the excited state of hlct, a kind of excimer bimolecular luminescence with high efficiency (~ 80%) and long life (~ 100-200 NS) was realized by using discrete π - π dimer stacking. A molecular design strategy for constructing high-efficiency π - π dimer stacking structure was proposed, and its application in OLED, stimulus response and biological imaging was initially demonstrated.In addition, through the molecular conformation folding to control the excited state properties and induce spin orbit coupling enhancement, a new design idea of high efficiency pure organic room temperature phosphorescent materials is proposed.In a word, around the design and control of excited states, we will discover new phenomena in photophysics, innovate luminescence mechanism, and strive for a new generation of luminescent material systems and characteristic applications with independent intellectual property rights.
Guest profile: Yang Bing, Professor, doctoral supervisor, School of Chemistry / State Key Laboratory of supramolecular structure and materials, Jilin University.He graduated from Jilin University in 2002.From 2002 to 2004, he was engaged in post doctoral research in the State Key Laboratory of supramolecular structure and materials.Prof. Jean Luc bredas, CO tutor of Department of chemistry and molecular biology, Georgia Institute of technology, 2011-2013.His research interests are mainly focused on the design and synthesis, theoretical simulation and device application of supramolecular optoelectronic functional materials. He has presided over and completed 9 projects of National Natural Science Foundation of China and 3 sub projects of national key R & D projects. He has been working in J. am. Chem. SOC., angel. Chem. Int. ed., adv. functMore than 180 papers have been published in international academic journals such as mater. And the papers have been cited more than 6000 times (h-index: 42).A series of innovative research achievements have been made in the field of new concept organic electroluminescent materials, and the fourth person won the first prize of Natural Science in Colleges and universities of the Ministry of education in 2008.