为营造浓厚的学术氛围，由我院承办的“材智荟·大讲堂”讲坛，将邀请沙特阿卜杜拉国王科技大学（KAUST）Omar F. Mohammed (奥马尔·默罕默德)教授前来讲学并做专题报告，欢迎广大师生积极参加！
报告题目：Mapping Charge Carrier Dynamics: From World-Record Perovskite
Solar Cells to Exceptional Performance of X-Ray Imaging Scintillators
报告人：Omar F. Mohammed (奥马尔·默罕默德)教授
报告时间：2024年7月10日（周三）9:30
报告地点：郑州大学材料科学与工程学院教学楼207报告厅
报告人简介：Omar F. Mohammed 教授，沙特阿卜杜拉国王科技大学（KAUST），物理科学与工程学部全职教授。 ACS Applied Materials & Interfaces期刊副主编，在《科学》、《自然》、《自然-材料》、《自然-能源》和《自然-光子学》等期刊上发表了 340 多篇文章，论文被引用近 38,000 次，h 指数为 91。2019到2023年连续5年被Web of Science评为全球高被引学者。穆罕默德博士主要研究领域包括开发高性能 X 射线成像屏幕，有机无机发光材料，和新的超快光谱与显微技术。穆罕默德博士还获得了如阿拉伯经济和社会发展基金颁发的杰出学者奖、德国长期研究金、日本科学促进会（JSPS）研究金、埃及国家基础科学奖、约旦舒曼光化学奖以及科威特国家物理学奖。
报告内容：The separation and collection of photo-generated charge carriers in light-harvesting devices are limited by the losses and ambiguous dynamical events at the surfaces and interfaces of the absorber layers. These events occur in ultrafast time scales and can only be visualized selectively in space and time by scanning ultrafast electron microscopy (the sole technique capable of surface-selective visualization of light-triggered carrier dynamics at nanometer and femtosecond scales). In this method, the surface of the photoactive materials is excited by a clocking optical pulse and the photo-induced changes will be directly imaged using a pulsed electron beam that generate secondary electrons with a couple of electron volts energy, which are emitted from the very top surface of the material in a manner that is extremely sensitive to the localization of the electron and hole on the photoactive material surfaces. This powerful technique along with ultrafast laser spectroscopy allow us to directly and precisely investigate and decipher the trajectory of charge carriers on materials surfaces and interfaces in real space and real time. Through this work, we have optimized the properties of photoactive materials for applications in light-harvesting devices that led to the world-record solar cell devices based on perovskite crystals. Moreover, we have clearly demonstrated in space and time how the surface orientations, surface oxidation and passivation can significantly impact the overall dynamical processes of photo-generated charge carriers in optoelectronic materials. Finally, I will talk about our recent ground-breaking work in X-ray imaging technology that includes multicolor scintillators, cutting-edge materials discovery, heavy-atom engineering, state-of-the-art characterization and efficient (nearly 100%) interfacial energy transfer between sensitizers and scintillators that has led to the development of novel X-ray imaging screens with outstanding sensitivity, ultralow detection limit, unprecedented spatial image resolution and low-cost fabrication, with potential applications in medical imaging, industrial monitoring and security screenings.
