题目：Broadband ultrafast photoluminescence spectroscopy and its application in material characterization

报告人：Kai Chen，Senior scientist (新西兰惠灵顿维多利亚大学)

时 间：2023年3月27号（周一）上午10：00-11：00

地 点：线下-理学楼B座203

摘要：

The spectral evolution of photoluminescence (PL) in ultrafast timescales provides a straightforward route to investigate photoexcitation processes. Various applications have been demonstrated many areas in chemistry, physics, biology, and material science. Accessing the crucial sub-picosecond timescale requires using nonlinear optical effects trigger by femtosecond laser pulses. However, the conventional nonlinear optical gating method, fluorescence up-conversion, suffers from narrow spectral bandwidth due to phase matching condition, while the broadband method, optical Kerr gating suffers from low sensitivity due to high background noise. From technical point of view, it still demands a high-performance ultrafast PL method to simultaneously satisfy the requirements of effectiveness, ultrafast time-resolution, high sensitivity, and broad spectral bandwidth. Here, we perform a novel ultrafast time-resolved PL spectroscopy system based on the transient grating PL spectroscopy technique and advanced femtosecond light sources. This combination enables us to achieve a high-performance ultrafast optical gate driven by high pulse energy, high repetition rate, and ultrashort laser pulses. This system can rapidly capture sub-picosecond emission dynamics from UV to near-infrared region. We will use case studies in optoelectronic materials as examples to highlight the capability and new applications of this advanced optical characterization technique for material sciences.

简历：

Dr Kai Chen received his Ph.D. in Physics at Victoria University of Wellington (VUW), New Zealand, in 2015, following which he worked as a postdoctoral fellow in the Ultrafast Spectroscopy Research group at VUW. Currently, he is a senior scientist at Robinson Research Institute at VUW and an associate investigator at both MacDiarmid Institute for Advanced Materials and Nanotechnology and the Dodd-Walls Centre for Photonic and Quantum Technologies. With research interests in optical characterisation techniques and optoelectronic materials, Dr Chen has developed multiple ultrafast spectroscopy techniques and utilised them in the study of several advanced materials such as organic semiconductors, molecular materials, semiconducting quantum dots, and perovskites.

联系方式：stephen.chen @bit.edu.cn

邀请人： 陈宇辉

网 址：/

承办单位：物理学院、先进光电量子结构设计与测量教育部重点实验室

*Title：Broadband ultrafast photoluminescence spectroscopy and its application in material characterization

*Reporter：Kai Chen, Senior Scientist, Robinson Research Institute Institute, Victoria University of Wellington, New Zealand.

*Time：March 27th 2023, 10:00-11:00

*Place：Physics Building B 203

*Contact Person: Yu-Hui Chen

*Abstract: The spectral evolution of photoluminescence (PL) in ultrafast timescales provides a straightforward route to investigate photoexcitation processes. Various applications have been demonstrated many areas in chemistry, physics, biology, and material science. Accessing the crucial sub-picosecond timescale requires using nonlinear optical effects trigger by femtosecond laser pulses. However, the conventional nonlinear optical gating method, fluorescence up-conversion, suffers from narrow spectral bandwidth due to phase matching condition, while the broadband method, optical Kerr gating suffers from low sensitivity due to high background noise. From technical point of view, it still demands a high-performance ultrafast PL method to simultaneously satisfy the requirements of effectiveness, ultrafast time-resolution, high sensitivity, and broad spectral bandwidth. Here, we perform a novel ultrafast time-resolved PL spectroscopy system based on the transient grating PL spectroscopy technique and advanced femtosecond light sources. This combination enables us to achieve a high-performance ultrafast optical gate driven by high pulse energy, high repetition rate, and ultrashort laser pulses. This system can rapidly capture sub-picosecond emission dynamics from UV to near-infrared region. We will use case studies in optoelectronic materials as examples to highlight the capability and new applications of this advanced optical characterization technique for material sciences.

*Profile：Dr Kai Chen received his Ph.D. in Physics at Victoria University of Wellington (VUW), New Zealand, in 2015, following which he worked as a postdoctoral fellow in the Ultrafast Spectroscopy Research group at VUW. Currently, he is a senior scientist at Robinson Research Institute at VUW and an associate investigator at both MacDiarmid Institute for Advanced Materials and Nanotechnology and the Dodd-Walls Centre for Photonic and Quantum Technologies. With research interests in optical characterisation techniques and optoelectronic materials, Dr Chen has developed multiple ultrafast spectroscopy techniques and utilised them in the study of several advanced materials such as organic semiconductors, molecular materials, semiconducting quantum dots, and perovskites.