Time: May 9th, 15:00
Tencent Meeting: https://meeting.tencent.com/dm/OQ256KWvzy7x
Meeting ID: 112 755 006
Host: Prof. Zhiyong Tang
Title: Ultrafast Charge Carrier Dynamics in Low-dimensional Perovskites Studied via Time-Resolved Spectroscopies
Speaker: Kaibo Zheng, Department of Chemistry, Technical University of Denmark and Department of Chemical Physics, Lund University, Sweden.
Abstract:
Lead halide perovskites (LHP) have been highly spotted as promising optoelectronic materials for one decade. Derived from their bulk counterparts, low-dimensional LHP nanostructures introduced new photophysical advances that may break the bottlenecks set by the conventional LHPs. For instance, two-dimensional Roddlesden-Popper LHPs are believed to provide high stability towards moisture that used to be the main issues for the solar cell application of LHPs. LHP nanoparticles, on the other hand, can achieve almost unity photoluminescence quantum yield with tunable emission wavelength. However, the low-dimensionality would also drastically change the electronic structures of the LHPs, and consequently modify the photophysics. There always remains a trade-off between the two sides. Therefore, obtaining a systematic picture on the excited state dynamics as well as its dependence on the structures of the low-dimensional LHPs become vital for their device application. We utilized a variety of time-resolved spectroscopic technics with wide range of time windows and probe wavelengths to investigate some crucial photophysical processes of low-dimensional LHPs including their charge carrier transport and recombination, defect trapping and de-trapping, hot electron cooling, polaron formation, inter-phase charge transfer or energy transfer, etc. These helps to rationalize the underlying mechanism when they are applied in specific devices. We also put special focus on the systematic comparison between low-dimensional LHPs and bulk LHPs. We expect this would provide new guidance for further material engineering and device optimization.
Bio：
Kaibo Zheng graduated from the Department of Materials Science, Fudan University, China, in 2010 with a PhD in Physical Electronics. From 2010 to 2018, he worked as a postdoctoral fellow in the Department of Chemical Physics, Lund University, Sweden.
He is currently employed as senior researcher at the Department of Chemistry, Technical University of Denmark and Department of Chemical Physics, Lund University, Sweden. His research interests include ultrafast dynamics and photophysical processes in nanostructured optoelectronic materials, device mechanism and carrier dynamics of photoactive low-dimensional structures, ultrafast structural dynamics of optoelectronic materials.
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