Research group of academician Huang Wei and Professor an Zhongfu of Nanjing University of Technology: development of organic long afterglow materials with long life and high efficiency

Lead organic long afterglow materials have been widely used in photoelectric and biological fields due to their long luminescence life, high quantum yield and large Stokes displacement However, due to their weak spin orbit coupling and fast non radiation attenuation, it is still a challenge to develop long-lived and high efficient organic afterglow materials Huang Wei, academician of Advanced Materials Research Institute of Nanjing University of Technology (IAM team) and Professor an Zhongfu's research group formed supramolecular framework structure by self-assembly of melamine and aromatic carboxylic acid compounds in aqueous solution, and obtained organic long afterglow material with long life and high efficiency at room temperature Its luminous life is up to 1.91 s, and the quantum yield of phosphorescence is up to 24.3% (j.am Chem Soc , DOI: 10.1021/jacs.8b03867 ）。 Brief introduction of academician Huang Wei, academician of Chinese Academy of Sciences, foreign academician and honorary doctor of Russian Academy of Sciences Professor, doctoral director, organic electronics / flexible electronics He is a distinguished professor of "Changjiang Scholars" of the Ministry of education, winner of National Science Foundation for Distinguished Young Scholars, national expert of "thousand talents plan" of the Central Organization Department, and chief scientist of "973" project of the Ministry of science and technology Honorary doctor of the University of Sheffield, member of the Royal Society of chemistry, second prize of the National Natural Science Award and winner of the "science and Technology Progress Award" of Ho Leung Ho Lee Foundation Academician Huang Wei is one of the world's first well-known scholars engaged in the research of polymer LED display and has been active in the fields of organic optoelectronics and flexible electronics for a long time Since the beginning of 1990s, it has been committed to the research of organic optoelectronics and flexible electronics, which are interdisciplinary and integrated and developed across many disciplines, such as physics, chemistry, materials, electronics, information and life In order to build the theoretical framework of organic optoelectronics, realize the high performance and multi-function of organic semiconductors, and promote the transformation and industrialization of scientific and technological achievements He has done a lot of pioneering, innovative and systematic research work and is the founder and pioneer of Organic Optoelectronics in China A large number of systematic and innovative research results have been obtained in organic optoelectronics, flexible electronics and other fields As the first or corresponding author, he has worked in NAT Mater., NAT Photon., NAT Nanotech., NAT Commun., adv mater, J More than 600 research papers have been published in SCI academic journals such as am Chem SOC., and more than 30000 citations have been made by peers More than 200 invention patents have been authorized or published in the United States, Singapore and China, and academic monographs such as organic electronics and biophotonics have been published Won the second prize of the National Natural Science Award, the science and technology progress award of He Liang He Li foundation, the achievement shortlisted for the "top ten scientific and technological progress of Chinese universities", the first prize of the natural science award of the excellent scientific research achievement award of the Ministry of education, the national excellent scientific and technological workers, the national special experts with outstanding contributions in the "thousand talents plan", the China production, learning and Research Cooperation Promotion Award, the fourth China University Excellent publication award, May 1st Labor Medal of Jiangsu Province, first prize of science and technology award of Jiangsu Province, first prize of educational science research achievement award of Jiangsu Province, first prize of excellent thesis of academic conference of philosophy and social sciences of Jiangsu Province, first prize of excellent achievement award of philosophy and social sciences of Jiangsu Province, and "top ten stars of science and technology" of Nanjing city Professor an Zhongfu, Professor, doctoral supervisor He graduated from Nanjing University of Posts and telecommunications in 2014 with a doctor's degree in engineering and studied with Academician Huang Wei Later, he went to the Department of chemistry of National University of Singapore to engage in postdoctoral research, and his co tutor was Professor Liu Xiaogang In September 2015, he joined Advanced Materials Research Institute of Nanjing University of technology for independent work Up to now, more than 40 SCI papers have been published in famous academic journals such as NAT Mater., J am Chem SOC., adv mater., angel Chem Int ed., adv funct Mater The paper has been cited more than 1200 times, and a single article has been cited up to 200 times He has been invited to attend academic conferences at home and abroad for many times 6 invention patents are disclosed or authorized Presided over general programs of National Natural Science Foundation, youth programs, outstanding youth funds and youth programs of Jiangsu Natural Science Foundation, and was selected into "six talent peaks" high-level talent plan of Jiangsu Province, and "entrepreneurship and innovation team" of Jiangsu Province He has won one first prize of Natural Science Award of Jiangsu Province excellent doctoral dissertation and excellent scientific research achievement award of the Ministry of education Introduction to the research group of Professor an Zhongfu since the establishment of the group in autumn 2015, there are 16 researchers, including 1 postdoctoral student, 2 doctoral students, 10 master students, and 3 graduate students from Inner Mongolia University, Taiyuan University of technology and other joint training The research group is engaged in the development of organic photoelectric functional materials, focusing on the research of organic long afterglow materials The research group is now recruiting several Ph.D students and postdoctors in chemistry, materials and optics Please send your resume to iamzfan@njtech.edu.cn Cutting edge research achievements: development of organic long afterglow materials with long life and high efficiency At present, there are two main ways to realize organic phosphorescence, one is to increase spin orbit coupling by introducing aromatic carbonyl, heteroatom or heavy atom, the other is to suppress non radiative transition of triplet exciton by means of crystal engineering, host guest doping, building metal organic framework and so on Based on these two ideas, researchers have made some progress and breakthroughs in extending the luminescence life of phosphorescent materials or improving their luminous efficiency However, due to their weak spin orbit coupling and fast non radiation attenuation, it is still a challenge to develop long-lived and high efficient organic afterglow materials Recently, Huang Wei, academician of Iam team of Nanjing University of technology and Professor an Zhongfu's research group formed supramolecular framework structure by self-assembly of melamine and aromatic carboxylic acid compounds in aqueous solution, and obtained organic long afterglow materials with long life and high efficiency at room temperature Its luminous life is up to 1.91 s, and the quantum yield of phosphorescence is up to 24.3% The multiple intermolecular interactions formed in the self-assembly process provide a strong rigid environment for the molecules The molecules are tightly locked in the three-dimensional network structure, which effectively limits the non radiation attenuation of the three-wire exciton and promotes the inter system crossing In addition, the material has been successfully applied to two-dimensional code recognition in dark conditions Relevant work was published on the top academic journal J am Chem SOC (DOI: 10.1021 / JACS 8b03867) in the field of international chemistry with the title of "simply enhancing efficiency and life time of ultralong organic Photoshop strength materials by molecular self assembly" This is a research group led by academician Huang Wei and Professor an Zhongfu, who successively published in the international top journals in the field of chemistry and materials (NAT Mater., 2015, 14, 685-690; adv mater., 2017, 29, 1701244; angelw Chem Int ed., 2018, 57, 678-682; angelw Chem Int ed., 2018, 57, 4005-4009; angelw Chem Int ed., 2018, 57, 8425-8431) After that, another important research achievement was made The first authors of this work are Bian Lifang, a graduate student, and Shi Huifang, an associate professor This work was supported by the "973 Plan" of the Ministry of science and technology, the National Natural Science Foundation and the natural science foundation of Jiangsu Province Fig 1 Structural design diagram of supramolecular framework (source: J am Chem SOC.) first, the author selected melamine (MA) and isophthalic acid (IPA) to self assemble after heating and dissolving in aqueous solution After gradient cooling, the supramolecular framework crystal ma-ipa with three-dimensional network structure was obtained, as shown in Fig 1 Its chemical structure was characterized by single crystal X-ray diffraction and elemental analysis The purity of the crystal was confirmed by powder X-ray diffraction Fig 2 Characterization of the photophysical properties of ma-ipa with supramolecular framework (source: J am Chem SOC.) after obtaining the single crystal, the author carried out a series of characterization of the photophysical properties of ma-ipa As shown in Fig 2, under the irradiation of the UV lamp, the needle like crystal is in a blue light-emitting state; when the UV lamp is turned off, the crystal presents a bright blue-green long afterglow According to the test data, the best excitation wavelength is 304 nm, the best emission wavelength is 466 and 488 nm, and the phosphorescence lifetime can reach 1.91 s Fig 3 Single crystal structure of ma-ipa (source: J am Chem SOC.) in order to further explore the mechanism of high efficiency and long afterglow luminescence, the author analyzed the single crystal structure of the supramolecular framework As shown in Figure 3, Ma, IPA and water molecules are connected by several short and strong hydrogen bonds and van der Waals force, and self-assembly forms a lattice like structure The noncovalent bond between molecules makes the molecules gather in a highly ordered supramolecular network Moreover, water molecules are connected with the upper and lower molecules through various hydrogen bonds, which hinders the molecular movement and reduces the non radiative transition of the triplet exciton, thus promoting the room temperature long afterglow In addition, it is found that self-assembly promotes the spin orbit coupling of molecules, which further proves the high efficiency phosphorescence of ma-ipa supramolecular framework Fig 4 Photophysical properties and single crystal structure of ma-tpa (source: J am Chem SOC.) in addition, the author carried out extended experiments to self assemble melamine (MA) and terephthalic acid (TPA) molecules in aqueous solution to form a ma-tpa supramolecular framework The photophysical properties and single crystal structure are shown in Fig 4 According to the test data, the luminescence lifetime of ma-tpa supramolecular framework is up to 1.09 s, and the quantum yield of phosphorescence is up to 19.4% The single crystal analysis and theoretical calculation show that the mechanism of ultra long organic phosphorescence is similar to that of ma-ipa Figure 5 Application of Ultra Long Phosphorescent Materials (source: J am Chem SOC.) finally, based on the unique properties of such ultra long organic phosphorescent materials, the author successfully applied them to two-dimensional code recognition in dark environment (Figure 5) Nowadays, people and scientific research have been paid more and more attention in the economic life China has ushered in the "node of science and technology explosion" Behind the progress of science and technology is the work of countless scientists In the field of chemistry, in the context of the pursuit of innovation driven, international cooperation has been strengthened, the influence of Returned Scholars in the field of R & D has become increasingly prominent, and many excellent research groups have emerged in China For this reason, CBG information adopts the 1 + X reporting mechanism CBG information, chembeangoapp, chembeango official microblog, CBG wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the domestic representative research group, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit.