Professor Georges ZISSIS, Toulouse 3 University, France

Lighting Scientist and Authority, Professor Georges ZISSIS, Toulouse 3 University, France

Prof. Georges ZISSIS, PhD, SMIEE, Vice-Rector Toulouse 3 University

Professor ZISSIS won the first Award of the International Electrotechnical Committee (IEC) Centenary Challenge for his work on normalization for urban lighting systems, the Energy Globe Award for France, and the Fresnel Medal from the French Illuminating Engineering Society. He has been awarded the title of Professor Honoris Causa of Saint Petersburg State University.

Georges ZISSIS [6,7] is Distinguish-class Professor in Toulouse 3 University and Director of “Light & Matter” research group of LAPLACE. He has published more than 156 papers in peer-reviewed referenced scientific journals (Hisch index 22), more than 300 papers in international conferences. He has given more than 90 invited lectures at international and national events. He was President of the Power Electronics, Electronics, Optoelectronics and System section of the French National Council of Universities and President of IEEE Industrial Application Society. He is Chairman of the 4E-Solid State Lighting Annex of the International Energy Agency and IEEE Smart Cities Initiative.

LED professional: Thank you for the opportunity to do this interview with you. Can we perhaps start by asking you about your professional background and how you came to the subject of light?

Professor Georges ZISSIS: I graduated in 1986 from the Physics department at the University of Crete (Greece) in general physics. Then I got my MSc and PhD in Plasma Science in 1987 and 1990 from Toulouse 3 University (France).

My relationship with lighting technology started during my third year in the Physics department at the University of Crete (Greece), in 1984, when one of my professors, Dimitris Karabourniotis proposed that I work in his laboratory on the modelling of the chemistry inside metal halide high pressure lamps. It was my fist contact with light sources and its complex physics. At the end of my studies, I obtained a French Government fellowship to continue my studies with a master and PhD in plasma physics in the University of Toulouse [1]. I integrated the team “High Intensity Light Sources” of the Centre of Atomic Physics of Toulouse (CPAT). I worked there in the framework of my PhD, under the direction of Prof. Jean-Jacques Damelincourt, on the modelling of fluorescent lamp plasma. After that I got a permanent position at Toulouse University in the electrical engineering department in the domain of Science and Technology of Lighting Systems, which had almost 40 years of history behind it.

Toulouse 3 University Campus.

LED professional: Could you explain your two functions/organizations: “Head of Light & Matter Research Group” and “Vice-rector for European and International Projects”?

Professor Georges ZISSIS: I am the director of the “Light & Matter” (L&M) research group [2] at the LAPLACE laboratory [3] that employs, on average, 20 researchers: 5 permanent academic staff, 3 research engineers (two with PhDs), 2 post-doc and 10 PhD (I haven’t counted the Master students here). LAPLACE stands for “Laboratory of Plasma and Conversion of Energy” It is a common research unit (UMR 5213) between the CNRS, the University of Toulouse 3, and the National Polytechnic Institute. It employs approximately 300 researchers, PhD students and staff members and it is subdivided into 12 research groups like L&M.

The Light & Matter research group, under my direction, is working on the production and use of light. We favor a holistic approach to the system. I coined the group’s strategy: consisting in understanding the functioning of a complex system, studying its components and their interactions, with the ultimate objective of optimizing the system according to its application and use. To perfect this optimization, we call upon our competences in modelling and diagnostics, without neglecting the prototyping and the demonstration on a large scale.

In parallel with my function as L&M head, I have a 4-year mandate as Vice-Rector of Toulouse University (4,500 staff members and 35,000 students) in charge of European and International Projects. In that frame, I am developing, with the staff members of my service at the central International Relations Office, a new strategy for our university in order to increase our international visibility through the coordination, or participation, of large-size European and International networking Projects (INTERREG, Euromed, etc.). Since my arrival 3-years ago, we obtained several new projects, and my service is managing a budget of 2-3 million Euros coming mainly from European programs. I have some other functions on an international level. For instance, in 2021, I created and I am chairing the IEEE Smart Lighting Project in the USA [4] and I have been chair person of the 4ESolid State Lighting Annex of the International Energy Agency [5] since 2019.

LED professional: What’s the goal of the IEEE Smart Lighting Project?

Professor Georges ZISSIS: This is a project that I initiated in 2021 within the IEEE Future Directions Committee (FDC).

It consists of the seeding of a ‘Smart Lighting Initiative (SLI)’ that will be carried out during the next 3 to 5 years. The project is financed by IEEE Smart Village. It is also strongly associated with IEEE Smart Cities Technical Community. In fact, Lighting fits perfectly with the IEEE mission for “Advancing Technology for Humanity” because artificial light generation is an inherent need for human beings and society. It consumes huge amounts of energy and resources, it impacts our performance, security, well-being and health, but also our environment and ecosystem. Lighting is a factor of sustainable development.

The Lighting Industry and ICT Industry are now rapidly evolving and converging. IEEE is willing to accompany this evolution. The project aims at clustering IEEE member’s expertise from various horizons (more than 400,000 members worldwide) and disciplines to advance in the science and technology of Smart Lighting Systems. Inside the project we are now working on, among other things, the creation of a flagship conference and expo, a white paper on smart lighting and an IEEE-level contest (XPrize-like) for smart lighting in poor and developing world regions. In parallel, we regularly organize webinars and workshops. These actions, as well as the participation in the IEEE Smart Lighting project, is open to all, whether they are IEEE members or not [4].

LED professional: What’s the intention of the 4E-Solid State Lighting Annex of the International Energy Agency?

Professor Georges ZISSIS: The SSL Annex was established in 2010 under the framework of the International Energy Agency’s Energy Efficient End-use Equipment (4E) Implementing Agreement to provide advice to the governments of its member countries seeking to promote energy efficient lighting and to implement quality assurance programs for SSL lighting. This international collaboration currently consists of the governments of Australia, Canada, Denmark, France, the Republic of Korea, Sweden and the United Kingdom. The Annex constitute a perfect ground for developing various activities. I can relate to some of the examples: The Annex have successfully organized and carried out two inter-laboratory comparisons, IC2013 and IC2017, where collectively 146 labs from around the world were compared for measurements of LED lighting products using integrating spheres and gonio-photometers. The IEA 4E SSL Annex is now considering whether to launch a 2022 Interlaboratory Comparison (IC 2022) for temporal light modulation (TLM) measurements. A report published recently, provides a look across the body of literature on lifetime definitions for LEDs and LED products. The report looks at failure mechanisms, accelerated life tests and test methods for estimating lifetime, and provides some recommendations.

There is currently no agreement as to which test method can best estimate the lifetime of LED lighting products and the report thus addresses a key issue for regulators and industry interested in deployment of LED technologies. Annex’s experts produce and regularly update voluntary quality and performance requirements which address product attributes such as color, lifetime, power, and efficacy for common SSL lamps and luminaires. The product performance requirements offer a limited number of performance levels, agreed upon by IEA SSL Annex members, that could be utilized by government, non-profit and donor agencies when designing programs and policies. The objective is to provide a limited number of levels that can be utilized by program designers to reduce costs of writing specifications and to facilitate economic advantages for industry/trade. Last but not least, Annex is working on Life Cycle Assessment for lighting products and also on impacts of artificial lighting on humans and our biotope. I could continue relating actions for a long time but it would be better to visit our web page to learn more. You can download very useful resources [5].

Mentors of Prof. ZISSIS: J.J. Damelincourt (1939-2008, left) from University of Toulouse 3, France, and D. Karabourniotis (1949-, right) from University of Crete, Greece.

LED professional: How did you experience the transformation toward solid-state lighting, and how did you align your institute with the new tasks?

Professor Georges ZISSIS: When I arrived in Toulouse, the research team High Intensity Light Sources, created in 1972 by Prof. Damelincourt, my mentor, was focusing on the study of electrical discharge lamps and that in CPAT, a 50year-old laboratory working on plasma science. Under those conditions one can imagine that the arrival of solid-state lighting could affect our work negatively. However, this didn’t happen! This can be explained by several facts:

1. Prof Damelincourt introduced the very first idea to extend our domain of activities from the discharge lamp to the lighting system. From my side, I had foreseen rather early the evolution towards SSLs.

2. The CPAT merged with 2 other laboratories to form LAPLACE: the laboratory of plasma and CONVERSION OF ENERGY. Producing light from a system is “Conversion of Energy”, there was no longer a need to stick with plasmas… The way to introduce SSL was open for me.

3. In the framework of the creation of LAPLACE (I was one of the 3 people that co-created and directed LAPLACE during its very first 4-years), I decided to merge my old team with another group coming from the LGET (another of the 3 clustered labs to form LAPLACE). This team, called ‘organic semiconductors’, was working on Organic Light Emitting Diodes and Organic Photovoltaics. The L&M group had been created!

Following the creation of L&M, our research themes were centered around the science and technology of light sources and lighting systems, as well as the study of the usages of light and its interactions with the environment and society. The themes of the group are inseparable from the applications. Although our activities are strongly linked to applications, they do not neglect fundamental aspects in the field of energy conversion, materials and systems, for lighting.

LED professional: What are the possibilities of collaborating with Laplace University in Toulouse, both from a research point of view and for possible industrial collaboration partners?

Professor Georges ZISSIS: The L&M team is well known and recognized in the domain of lighting systems. Our visibility is coming from both academic and valorization actions. For instance, my group publishes around 15 papers in peer-reviewed journals, every year and we are regularly invited to give talks in important conferences, and we collaborate with many academic institutions worldwide working in the domain of lighting and lighting usages. Add to that more than 90 PhDs delivered since 1972. Concerning the valorization aspects, beyond 12 patents and the successful creation of 2 spin-offs, since the creation of the group in the 1970’s, we had the opportunity to collaborate on a contractual basis with all the major lighting manufacturers, worldwide. Today this activity is amplified, for instance, in the direction of High-Tech SMEs on both national and international levels. Our various industrial collaborations consumed more that 10 million Euros in resources either from national, European, international projects, or directly from industry. This clearly illustrates the sincere will of L&M to work hand-in-hand with industry and any other actor in the domain of lighting systems. L&M, beyond various resources (set-ups, staff, databases), has a wide area of expertise in the domain of lighting that is always valuable to our partners. This is, in my eyes, a “winwin” situation.

LED professional: Let’s discuss the International Symposium on the Science and Technology of Lighting. Can you please give us some background on the history and development of this event?

Professor Georges ZISSIS: The International Symposium on the Science and Technology of Lighting (LS-series) always aims to provide an excellent forum for scientists and engineers worldwide, in both academia and industry, to share and exchange the latest progress on the Science and Technology of Lighting Systems. The LS-series has a more than 45-year history and since the 1st LS (LS:1) in 1975 in Loughborough, United Kingdom, it has been held regularly in 2 or 3-year intervals on various continents. The event was supported substantially by the legacy lighting industry and the quality of papers presented in the various LS meetings was (and still, is) very high. Note that one of the first public blue LED demonstrations by Shuji Nakamura took place during an LS meeting in Greifswald, Germany. There were 460 people in attendance at that meeting. Especially for this time, the 17th LS in Toulouse has been collocated with the 11thInternational Conference on Energy Efficiency in Domestic Appliances and Lighting (EEDAL). Globally, we had 263 attendees (148 in-person and 115 in remote mode) for a global number of 149 papers accepted. This is a very nice score especially under pandemic conditions. The delegates came from 36 countries distributed throughout 5 continents. Roughly two thirds of the delegates were from academia and various organizations and one third was from industry.

Ombroscopy set-up. Ombroscopy is an optical technique that visualizes air’s refraction index variations due to convective heat evacuation from hot spots. It allows researchers to “see the invisible”.

White light investigations are performed in LAPLACE by exposing yellow phosphor to violet laser diodes (1.8W in this set-up).

During the traditional steering committee meeting we decided to transfer LS to IEEE Smart Lighting and transform it in a flagship annual event, keep the LS acronym and change the name of “IEEE Sustainable Smart Lighting World Conference and Expo” (this is not definitive), the pilot event will take place in Bombay in June 2023.

LED professional: The LS 2022 recently took place in Toulouse. What was the restart like after the Coronarelated break, and how did it go overall for the organizer?

Professor Georges ZISSIS: Corona, had a certain impact on the LS organization. The conference was postponed from November 2021 to June 2022 in order to draw in-person participants because this the “signature” and the “essence” of the LS-series.

Then it was decided to have the LS in a hybrid format: both in-person and remote participation. This implied additional constraints because all sessions (up to 5 parallel sessions) had to be broadcast in real-time for remote participants and recorded for accessing them remotely and kept available for two months after the conference. Fortunately, IEEE gave us access to a specialized platform to support that hybrid event. Although the hybrid LS outcome was a success, both scientifically and financially, (thanks to my research team members who worked very hard), I can say that the organization for a hybrid event is a “mesh” and I’ll never do it again. Or if I have the obligation to do so, I’ll ask for a registration fee much more expensive for remote than for inperson participants).

LED professional: What topics were discussed? And which ones were in the foreground? Can you determine trends for lighting research and the lighting industry based on this event?

Professor Georges ZISSIS: Based on the various papers presented at the LS, it is indeed possible to outline some trends for the future:

a. Research on legacy technologies is still there but without any concrete industrial future. However, for academics many interesting fundamental questions need further exploration.

b. LED technology is fully mature, associated metrology and standardization aspects are actively addressed with success. New technologies, like OLEDs, solid state lasers are around the corner but, difficult to say what the evolution will be.

c. Smart Lighting Systems and associated services are the future directions to go. Social issues, environmental impacts, including light pollution, need to be addressed. Lighting economics and life cost assessment are rising aspects.

d. Training of lighting professionals in the modern lighting technologies and associated constraints is a hard point. Today, many existing training programs for lighting professionals are outdated and need to be refurbished.

LED professional: What directions will the new light sources like LED, OLED, Micro-LED, take? Will laser light be an issue, or how do you see the bioluminescence light sources?

Professor Georges ZISSIS: The direction that will be taken in the next years is clearly smart lighting, whatever the light source itself will be. Micro-LED is definitely a technology that will allow some new performances like flexible light sources that LEDs can’t achieve. White light created from RGB micro-LEDs is expected to achieve higher luminous efficacies than phosphor converted LEDs, but the green gap is still there… OLEDs are flexible, foldable and they don’t suffer from green gap. However, many problems need to be addressed before the technology becomes mature for general lighting. Micro-LEDs can jam this progression. Laser light, can constitute a valid solution in the case of high currents and high luminous fluxes. It is increasingly being adapted for being coupled with information transfer via VLC, which is one of the flagship characteristics of smart lighting systems. More experience in the domain is needed to decide the path to follow.

LED professional: What contribution can the lighting world make concerning the global rise in energy prices?

Professor Georges ZISSIS: Energy prices will increase inexorably and rapidly, if not exponentially, during the next few years. Unfortunately, there are no actions that can change that tendency. Electrical lighting absorbs 13-14% of the annual electricity generated in our planet today. A large part of that energy is still spilled. Smart lighting can help to save spilled energy. Of course, any energy saved reduces the bill of the end-users even if the energy’s price is increasing. However, we must be very careful. Using more energy efficient products without any limit, may have a deleterious effect. With more energy efficient products, prices decrease with technology maturity (SSL systems in our case), and the consumers are tempted to ask for more outcome (light). This anarchic growth leads to the annihilation of all energy savings linked to the only efficiency, and that in less than a decade. This is the famous “rebound” effect as described by Jevons in 1865, called also “Jevons paradox”. Smart Lighting systems can help to avoid the effects of this paradox.

Four green OLEDs made in L&M LAPLACE –40% of the matter used in the OLED stack is bio-sourced (β-Carotene).

3D reconstruction of an LED component in an LED lamp using X-ray tomography. A way to investigate defects without having to intervene.

LED professional: Let’s discuss the future of light in general terms. What directions for the world of light can you identify and, by extension, what will you be working on intensively in Toulouse over the next few years?

Professor Georges ZISSIS: To me, the right direction for lighting is to put the stress on Sustainable Development and Affordability issues exploring Smart Lighting’s capacities.

As far as I’m concerned, this can be achieved though the SSL2 concept that I coined recently: “Sustainable Smart Lighting (1st SSL) system uses and optimizes, in an intelligent way, the best existing technology. Solid State Lighting (2nd SSL), to best fulfil present needs for artificial light, and reduce undesirable side-effects, without compromising the ability of future generations to innovate.” This may lead to a smart system that lights-up smart, in a sustainable & affordable way, where it is needed, when it is necessary and as good as possible!

Developing a new metrics that can quantify the “efficiency”, “sustainability” and “affordability” of a such system is a cross-discipline subject. A part of my team is working on this axis. In parallel, we continue our efforts to produce Organic Light Emitting Diodes based exclusively on bio-sourced materials. Just imagine an OLED using molecules from carrots and algae, exempt from ITO. This is not science-fiction, but for the moment, I can’t say more for obvious IP reasons.

LED professional: Which team or research groups are available to you for this? Would you also be interested in industry partners in specific areas?

Professor Georges ZISSIS: As I mentioned before, my team has privileged collaborations with various academic institutions and industry worldwide. Further, IEEE Smart Lighting offers an excellent basis for structuring such collaborations. However, we are fully open to new collaborations within the industry in the domains of organic light emitting components and lighting system quality and efficacy enhancement.

LED professional: Thank you very much for taking us on this exciting lighting journey and giving us a glimpse into your extensive work.

Professor Georges ZISSIS: We wish to thank LED Professional for the opportunity to give this interview. ■

References

[1] Toulouse III University https://www.univ-tlse3.fr [2] Light & Matter Research Group http://www.laplace. univ-tlse.fr/Lumiere-et-Matiere [3] LAPLACE Laboratory http://www.laplace.univ-tlse.fr [4] IEEE Smart Lighting Project https://cmte.ieee.org/fu turedirections/projects/smart-lighting/ [5] 4E Solid State Lighting SSL Annex https://www.ie a-4e.org/ssl/ [6] Prof. ZISSIS on LinkedIn https://www.linkedin.com/i n/georges-zissis-9b88887/ [7] Prof. ZISSIS on CV Archives https://cv.archives-ouv ertes.fr/georges-zissis