laboratoire pierre aigrain
électronique et photonique quantiques
laboratoire pierre aigrain

Seminar, June 11th 2018 (13h30 salle L 363-365)

Xiong Qihua - NTU singapore
Room-temperature strong light-matter coupling and polariton condensation in perovskite materials

Strong light-matter coupling have been reported in a wide range of organic and inorganic semiconductors, while demonstrations of the polariton condensation and the subsequent polariton lasing are limited within a handful of semiconductors at both low and room temperatures. In inorganic materials, polariton condensation significantly relies on sophisticated epitaxial growth, while organic active media usually suffer from large threshold density (closed to the damaging threshold of the organic active medium) and weak nonlinearity due to the Frenkel exciton nature. In this respect, strong efforts have been done in hybrid organic-inorganic perovskite materials, as they combine the advantages of both inorganic and organic materials. However, up to now, only the room-temperature strong coupling regime was observed in such materials [1, 2]. The all-inorganic perovskite and more precisely the cesium lead halide perovskites are part of a new class of materials that are currently drawing attention to the photonics community. The epitaxy-free synthesis combined with their excellent optical gain properties with large exciton binding energy and oscillator strength, tunable emission band from UV to NIR by substitution of the halogen atom, and better optical stability under high laser flux illumination compared with hybrid perovskites [3], promise further important technological developments.
In this talk, I will first present our results on synthesis of high quality hybrid perovskite materials and their optical properties, then I will present polariton condensation and polariton lasing at room temperature in CsPbCl3 nanoplatelets embedded in a planar microcavity [4]. These effects are unambiguously evidenced in the blue region of the visible spectrum by superlinear power dependence, macroscopic ground state occupation, blueshift of the ground state emission, narrowing of the linewidth and the build-up of long-range spatial coherence. Next, I will present our latest results on room-temperature strong light-matter coupling in CsPbBr3 nanowires embedded in a planar microcavity, where a polariton emission characterized by the typical polariton dispersion in laterally confined nanostructures is clearly evidenced in the green region of the visible spectrum. Such successful realization of room-temperature strong light-matter effects at different wavelengths and in different perovskite crystals geometries advocates the considerable promise of perovskite materials for polaritonics applications.
1. J. Wenus et al., Phys. Rev. B 74, 235212 (2006).
2. G. Lanty et al., Appl. Phys. Lett. 93, 081101 (2008).
3. Q. Zhang et al., Adv. Funct. Mater. 26, 6238-6245 (2016).
4. R. Su et al., Nano Lett. 17, 3982, (2017).
5. R. Su et al., manuscript submitted, (2018).

Biography : Qihua Xiong is currently Professor of Physics and Electrical Engineering at School of Physical and Mathematical Sciences, Nanyang Technological University. He received his B.S. degree in physics from Wuhan University in 1997, and obtained his M.Sc. degree from the Shanghai Institute of Applied Physics, Chinese Academy of Sciences. He went to the United States in 2000 and received Ph.D. degree under the supervision of Prof. Peter C. Eklund from The Pennsylvania State University in 2006. After three years postdoctoral experience in Prof. Charles M. Lieber’s group at Harvard University, he joined Nanyang Technological University as an assistant professor in 2009 and promoted to Nanyang Associate Professor in 2014. He was promoted to full Professor in 2016. He is the Associate Chair of the school taking careful Faculty portfolio. He is a Fellow of Singapore National Research Foundation awarded in 2009 and the inaugural NRF Investigatorship Award by Singapore National Research Foundation in 2014. He is the recipient of IPS Nanotechnology Physics Award (2015) and Nanyang Award for Research Excellence of NTU (2014). Prof. Xiong’s research focuses on light-matter interactions of emergent quantum matter by optical spectroscopy approaches, such as semiconductor nanomaterials, 2D transitional metal chalcogenides and halide perovskite materials. He has more than 180 papers published, which attracted 7600 citations with an H-index of 51. Starting from this year, he serves as the associate editor for Optics Express, the flagship open access journal of Optical Society of America.