報告題目： High-efficiency Perovskite LEDs And Their Applications
報告人： 徐魏棟 （瑞典林雪平大學）
A major efficiency limit for solution-processed perovskite optoelectronic devices (e.g. light-emitting diodes, LEDs) is trap-mediated non-radiative losses. Defect passivation using organic molecules has been identified as an attractive approach to tackle this issue. However, implementation of this approach has been hindered by a lack of deep understanding of how the molecular structures affect the passivation effectiveness. Firmly based on our new understanding of the passivation mechanisms, we significantly enhance the interaction with defects sites and minimize non-radiative recombination losses. Consequently, we achieve exceptionally high-performance near infrared perovskite LEDs (PeLEDs) with a high external quantum efficiency (EQE) of 21.6%. We find that our devices can also work efficiently in an emitting/detector switchable mode, with tens-megahertz speed for both functions. Benefiting from the small Stokes shift of perovskites, the diode shows high specific detectivity (>2×1012 Jones) at its peak emission (~ 800 nm), allowing optical signal exchange between two identical diodes. We further demonstrate the potential of the dual-functional diode for biomedicine diagnosis applications (as a monolithic heart pulse sensor) and for inter- and intra-chip bidirectional optical communications. [Refs.: Nat. Photon. 13, 418 (2019); Nat. Commun. 10, 2818 (2019)]
XU Weidong has been a postdoc researcher at Linkoping University (LiU) in Sweden since 2017. His research interests are organic/perovskite semiconductor devices and device physics, aiming for display and energy applications. He did his Ph.D study in Nanjing University of Posts and Telecommunications from 2010 to 2016 in Prof. Wei Huang’s group, when he investigated organic semiconductor and their application in light-emitting diodes and photovoltaics.