| 报告题目 | Exciton dynamics and its effects in the organic single crystal semiconductor rubrene |
| 报告人 | Prof. Ivan Biaggio |
| 报告人单位 | Lehigh University |
| 报告时间 | 2014-03-19 |
| 报告地点 | 合肥微尺度物质科学国家实验室九楼会议室 |
| 主办单位 | 合肥微尺度物质科学国家实验室、中国科学技术大学物理学院 |
| 报告介绍 | 报告摘要：
This talk will present an overview of recent discoveries about singlet and triplet excitons and their interaction in rubrene, a molecular crystal currently under intense study as an organic semiconductor for electronic and optoelectronic applications. Photon absorption in this material directly results in the creation of singlet excitons, whose radiative recombination leads to a photoluminescence spectrum that is strongly affected by the anisotropic crystal properties. At the same time, the space and time dependence of the photoluminescence is influenced by a peculiar exciton dynamics that is characteristic of organic crystals: The very efficient spin-conserving transformation of singlet excitons into triplet excitons (fission) and the ability of two triplet-excitons to combine to re-create a singlet exciton (fusion). These effects allow for the photogeneration of large triplet exciton densities, leading on the one-hand to the appearance of a strong delayed photoconductivity signal and on the other hand to a similar long-lived photoluminescence signal. In addition, efficient fission and fusion also allow the study of triplet-exciton diffusion by the detection of the spatial dependence of the photoluminescence emitted through the fusion process. Using this investigative technique we demonstrated long-range triplet diffusion in rubrene, with a large diffusion length of 4 micrometers.
报告人简介：
Prof. Ivan Biaggio received his Ph.D. in physics in 1993 from the Swiss Federal Institute of Technology (ETH) in Zürich, with a thesis on photorefractive effects induced by short light pulses. He then held a post doctoral position in the group of Prof. R. W. Hellwarth at the University of Southern California, where he worked on nonlinear optical effects in atomic vapours, optical correlators, and polaron mobility in Bi12SiO20. After a post doctoral stay with the group of Prof. G. Roosen at the Institut d'Optique Théorique et Appliquée in Orsay, France, working on applications and modelling of the photorefractive effect in the semiconductor crystal Cadmium Telluride (CdTe), he returned to the Nonlinear Optics Laboratory at ETH in 1996 to become the leader of the Photonic Materials Technologies team, where he worked on the nonlinear optical properties and charge transport properties of BaTiO3, KNbO3, Bi12SiO20, and DAST (an organic salt), touching such topics as the charge carrier mobility anisotropy in KNbO3 and BaTiO3, large polaron theory in a multi-mode polar lattice, the hole-mobility in KNbO3, the 2nd order nonlinear optical contributions to degenerate four-wave-mixing in non-centrosymmetric materials, and organic thin film systems for electronics and photonic applications. He received the venia legendi from ETH in 2001, went to Lehigh as an Associate Professor in October 2002, and became a Full Professor in 2010. He is working on condensed matter physics and light-matter interaction, including topics such as organic materials for third-order nonlinear optics and optoelectronics, laser spectroscopy, and pump and probe investigations of photoexcitation processes in various systems. |
