Speaker:Prof. Bin Liu

Time: 10:00 AM, March  29, 2024

Venue: Room  N308, Building of State Key Laboratory of Luminescent Materials and Devices, Wushan Campus

Abstract:

Commercial carbazole (Cz) has been widely used to synthesize organic functional materials, which are entwined with recent breakthroughs in ultralong organic phosphorescence, thermally activated delayed fluorescence, organic luminescent radicals, and organic semiconductor lasers. Recently, we discovered that different from commercial Cz, the fluorescence of lab-synthesized-Cz (Lab-Cz) is blue-shifted by 54 nm and the well-known room-temperature ultralong phosphorescence almost disappears. Detailed studies reveal the presence of a Cz isomer as the impurity, which is widespread in commercial Cz sources with <0.5 mol%. Ten representative Cz derivatives were resynthesized from the Lab-Cz and all failed to show the reported ultralong phosphorescence in the same crystal states. However, even 0.1 mol% isomer doping can recover the reported ultralong phosphorescence. The presence of the isomer in commercial carbazole tiggers us to re-examine the structure-property of many optically active materials. Interesting results have also been obtained for molecules with thermally activated delayed fluorescence and organic photosensitizers. 

Brief introduction of reporter：

Professor Bin Liu is Tan Chin Tuan Centennial Professor at the National University of Singapore (NUS). Bin graduated with bachelor’s degree from Nanjing University and a Ph.D. in Chemistry from NUS. She had postdoctoral training at the University of California, Santa Barbara before joining NUS in late 2005. Bin has been well-recognized for her contributions to polymer chemistry and organic nanomaterials for energy and biomedical applications. She is an international member of the US National Academy of Engineering. Since 2019, she has served as the Deputy Editor to launch and develop ACS Materials Letters, a flagship materials journal of the American Chemical Society.