报告题目：NIR-emitting PbS quantum dots: energy structure, self-assembly and energy transfer

报告人：Aleksandr Litvin

主持人（邀请人）： 张晓宇

报告时间：2019年9月27日上午9：30

报告地点：南区唐敖庆楼D区429报告厅

主办单位：材料科学与工程学院，汽车材料教育部重点实验室

摘要：PbS quantum dots (QDs) possess unconventional energy structure which governs their optical properties and energy transfer processes in their ensembles. First, we revealed a QD size-dependence of the energy of unconventional long-lived "in-gap" electronic state and showed that the existence of the in-gap state drastically affects optical properties of PbS QDs of different sizes. Second, we found that optical properties of ensembles of close-packed QDs are also controlled by the Forster resonant energy transfer (FRET). An analysis of FRET between QDs of different sizes shows that the in-gap state of donor-QD can act as initial state of photoexcitation. That leads to significant increase of PL decay time of acceptor-QD. This phenomenon may be regarded as FRET-activated delayed fluorescence. We also showed that participation of the in-gap state in FRET inside close-packed ensemble of QD of different sizes causes a merge of PL decays recorded at different spectral regions.

报告人简介：Aleksandr P. Litvin is a researcher at ITMO University, Saint-Petersburg, Russia, where he received his Masters degree in Photonics in 2012 and his PhD in Physics in 2015. In 2011 he spent three months at Trinity College Dublin (Ireland) in the group of Prof. Tatiana Perova. His current scientific interests are in the area of the NIR nanophotonics, and his research activity is focused on optical properties, plasmonic phenomena and energy transfer processes in semiconductor nanoparticles, as well as their application in optoelectronics.