时间：2023年12月15日（周五）10:00-11:30 

Time：10:00-11:30 AM, Friday, Dec. 15, 2023

地点：西湖大学云谷校区E10-222阶梯教室

Venue: E10-222, Yungu Campus

主持人：西湖大学理学院讲席教授/人工光合作用与太阳能燃料中心主任 孙立成

        西湖访问教授 高峰

Host: Prof. Licheng Sun, Chair Professor of School of Science & Director of Center of Artificial    Photosynthesis for Solar Fuels

      Prof. Feng Gao, Westlake Fellow

主讲人/Speaker：

Tönu Pullerits

Full Professor of Chemical Physics

Lund University

Member of the Royal Swedish Academy of Sciences

报告题目/Title:

Photonic Processes in Metal Halide Perovskite Nanostructures, from 0D to 2D

讲座摘要/Abstract:

Examples of our recent studies on perovskite nanostructures will be presented. We investigate two-photon-excited photoluminescence of CsPbBr3 perovskite quantum dots on a silicon photonic crystal slab. By systematic excitation of optical resonances using a pulsed near-infrared laser beam, we observe an enhancement of two-photon-pumped photoluminescence by more than 1 order of magnitude when compared to using a bulk silicon film. Experimental and numerical analyses allow relating these findings to near-field enhancement effects on the nanostructured silicon surface. In another study, we investigate hot carrier (HC) cooling in two-dimensional (2D) perovskite single crystals by applying two complementary ultrafast spectroscopy techniques – transient absorption (TA) and time-resolved two-photon photoemission (TR-2PPE) spectroscopies. TR-2PPE directly maps the hot electron distribution and its dynamics in the conduction band to the detected photoelectron distribution. While TR-2PPE selectively probes the upper layer of the material, TA provides information on the whole bulk. Two cooling regimes are resolved in both techniques. The fast timescale of 100–200 fs is related to the electron scattering by longitudinal optical (LO) phonons and the slow timescale of 3–4 ps corresponds to the LO phonon relaxation. The HC cooling dynamic of TA measurement has faster initial stage and higher starting temperature for the slower stage than in TR-2PPE measurements. Conclusions about spatial sensitivity of the cooling dynamics across the 2D perovskite single crystals constitute valuable information that can guide the future development of HC solar cells and thermoelectric applications based on 2D perovskites.

讲座联系人/Contact:

科技合作部Sci-tech02@westlake.edu.cn