Speaker：Hu Zhongjian, Los Alamos National Laboratory, USA
Invited by：Prof. Xiong Wei
Time：10:00-12:00, June 13, 2018
Venue: A101
Abstract：
In developing high-performing conjugated polymers (CPs) for plastic optoelectronics, a fundamental understanding about morphology-photophysics relations is of vital significance. Here, we employed single molecule spectroscopy (SMS), in conjunction with model polymers with controlled structural features, to unmask the morphology and photophysics, from single molecule up to bulk state. Effect of morphology on energy migration was probed via nanoscale aggregates with controlled morphology, which were assembled from single molecules during solvent-vapor-annealing with in-situ optical imaging. Fluorescence blinking and photon correlation analysis suggest that highly ordered interchain packing is in favor of long-range interchain energy migration, while disordered packing, long interchain distance, and competitive intrachain coupling significantly impede the interchain energy migration. In addition, by studying fluorescence quantum yield of aggregates formed in different solvents, we revealed the existence of charge-transfer state, which is a major factor for the low emission efficiency of CP films. Furthermore, composite CP/fullerene nanoparticles were fabricated and fluorescence-voltage SMS technique was developed to study charge trapping and excitations interactions in hole-injection devices. Pronounced charge carrier trapping was demonstrated in these nanoparticles, indicating their promising applications in nanoscale memory and imaging devices.
