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PGI-1 Talk: Dr. Christoph Wolf

The Interesting Opto-Electronic Properties of Lead-halide Perovskites: Application to Light-Emitting Diodes

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09 May 2018 11:30
venue
PGI Lecture Hall

Ewha Woman University, Seoul

Abstract:

The field of lead-halide based perovskites (LHP) with the generic formula APbX3, A being an inorganic or organic cation and X a halide, has recently attracted great attention as potential highperformance absorber in solar cells and emitter material in light-emitting diodes. Between the years 2014 and 2016 our group has pioneered performance increase in LHP LEDs, with record current efficiencies of about 40 cd/A and external quantum efficiency (EQE) ~10% in the green region around 540 nm (in comparison, 10~20% EQE is a respectable value for III-V semiconductor LEDs). During this fast engineering advance understanding of fundamental physics was often lacking.
In this talk, I will focus on discoveries of the fundamental photo-physics of LHP materials and will bridge the gap between science and engineering efforts. I will show how discoveries from ultrafast THz spectroscopy, low-temperature time-resolved spectroscopy and calculations from firstprinciples have lead from a change of paradigm and changed the concept of an excitonic system to one of large polarons which reconciles optical and electronic properties such as moderate charge carrier mobility and long-lived excited states. Christoph Wolf obtained his BSc. and MSc. in engineering physics from University of Technology Graz, Austria with works on non-volatile resistive memory switches. He obtained his PhD. In materials science and engineering from Postech University, Republic of Korea in 2017 with a focus of optoelectronic characterization of novel hybrid lead-halide based semiconductors by time-resolved spectroscopy and first-principles calculation. After a post-doctoral stay in Seoul National University he joined the efforts of establishing a new IBS research center for quantum nanoscience (QNS) in EWHA Womans University in Seoul. His research focuses on ab-initio calculations for magnetic phenomena on surfaces with the long-term goal of quantum-computing.

Contact

Prof. Dr. Samir Lounis
Phone: +49 2461 61-4068
Fax: +49 2461 61-2850
email: s.lounis@fz-juelich.de

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