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Photonics for Life: Self-organized Nonlinear Optics & Photonic Devices

Speaker:Prof. Jean-Michel Nunzi
Affiliation:Department of Physics, Engineering Physics and Astronomy, Department of Chemistry Queens University, Kingston, Ontario, Canada
Date:June 6, 2019 (Thursday)
Time:2:30 p.m.
Venue:Room 522, 5/F, Chong Yuet Ming Physics Building, HKU


Our team studies self-organization and the instrumentation related to organic photonic materials and devices. Major questions we try to answer are: what does light do for us and what do we get from the sun1?
For instance, there currently exists a significant demand for IR broadband photoresponsive devices for applications ranging from photovoltaics and renewable energy to photodetection for military and civilian purposes. When considering the effectiveness of those photosensitive devices, several factors must be considered including photoresponsivity, fabrication process, and cost. Moreover, the spatial resolution of IR photodetectors can be significantly improved by simultaneously sensing the intensity and polarization of the incident light.2
Photodetection through conventional procedures is based on light absorption by a material with a matching bandgap. However, this approach limits the range of wavelengths that can be detected, it is not sensitive to polarization, and cannot be used accurately in the infrared range because of thermal noise.3 Recent approaches have attempted to circumvent these limitations.4
Metal–semiconductor Schottky junctions have been reported as the most efficient structures to collect hot electrons5 and generate a signal in photodetectors. However, previously reported photodetectors based on this methodology can be very costly to fabricate, and not suitable for large-scale fabrication. Herein, we demonstrate that ITO-Au nanostructures can indeed be used to fabricate a NIR photodetector6 using the rectification effect induced by dipole orientation in a thin fim.7
Our designed device structure allows the fabrication of hot electron-based photodetectors that are highly sensitive in the NIR range, that are sensitive to polarization, and that are easy and cost-effective to fabricate. The approach developed herein represents a significant milestone towards the development of energy conversion devices based on hot electrons and plasmonics, which will be beneficial to integrated optoelectronics and photocatalysis.
1. Lewis, N.S., Basic research needs for solar energy utilization, 2005,
2. Zhang, E. et al., tunable ambipolar polarization-sensitive photodetectors based on high-anisotropy ReSe2 nanosheets. ACS Nano 2016, 10, 8067.
3. Mandal, P.; Sharma, S., Progress in plasmonic solar cell efficiency improvement: a status review. Renew. Sust. Energy Rev. 2016, 65, 537.
4. Wen, L. et al., Enhanced photoelectric and photothermal responses on silicon platform by plasmonic absorber and omni-schottky junction. Laser Phot. Rev. 2017, 11, 1700059.
5. Lee, Y.K. et al., Hot-electron-based solar energy conversion with metal-semiconductor nanodiodes. J. Phys. Cond. Matter 2016, 28, 254006.
6. Mirzaee, S.M.A.; Lebel, O.; Nunzi, J.M.,A simple unbiased hot-electron polarization-sensitive near-infrared photo-detector.ACS Appl.Mater.Inter. 2018, 10, 11862.
7. Sentein, C.; Fiorini, C.; Lorin, A.; Nunzi, J.M, Molecular rectification in oriented polymer structures.Adv. Mater. 1997, 9, 809.

Jean-Michel Nunzi graduated from l’Ecole de Physique et Chime, Paris in 1982, he joined l’Ecole Polytechnique for a PhD on the nonlinear optics of surface plasma waves (plasmons). He was then hired as full-time Researcher in Organic Photonics at the Atomic Energy Commission (Saclay) in 1984.
He joined the Department of Physics at the University of Angers as Professor in 2000, where he built the Plastic Solar Cells Technology Research Team.
He moved to Queen’s University as Tier 1 Canada Research Chair in Chiral Photonics in 2006, renamed Photonics for Life in 2013. He studies Organic and nano-Photonics, including the Chemistry, Instrumentation, Processing and Physics of nanomaterials and devices. His Google H-factor is 52.

Coffee and tea will be served 20 minutes prior to the seminar.

Anyone interested is welcome to attend.