Oral-History:Antonio Luque Lopez

About Antonio Luque López

Antonio Luque was born in 1941 in Malaga, Spain. Inspired by the novels of Jules Verne he decided to become an engineer; a stint as a ham radio operator moved him towards telecommunications engineering. He studied at the University of Madrid, with a one-year fellowship in Toulouse, France. His doctoral research was on lasers, and he became interested in the newly-born field of semiconductor research. He became a full professor of Electronics at the University of Madrid by 1970, at a young age, and was soon head of the Semiconductor Laboratory. During a visit to America ca. 1974 Luque became aware of the even-newer field of photovoltaics (solar energy) and decided to shift focus there, where he and Spain could do leading-edge research. In 1979 the Semiconductor Laboratory became the Institute for Solar Energy; since then it has grown slowly but steadily in quality and numbers. A second attempt at manufacture, this time of solar cells, produced the successful company of Isofoton, based at first on Luque’s invention of the bifacial solar cell. With some outside assistance and takeovers (Abengoa and Alcatel early, Verges later), Isofoton has now become profitable, one of the top ten photovoltaic firms in the world. Luque himself departed from the company in 1989, and he has not profited from its recent success, but they have remained on amicable terms. Since then, Luque has worked on solar concentrators with BP Solar and British Petroleum (the EUCLIDES program), to the point where it is near to commercial viability. He has also started work on an intermediate band solar cell, and thinks it has real possibilities. He has received various awards during the course of his career, and is proudest of the National Prize for Technological Research and the Jaime I medal.

About the Interview

ANTONIO LUQUE LÓPEZ: An Interview Conducted by Frederik Nebeker, IEEE History Center, 3 July 2002

Interview # 420 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.

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Antonio Luque López, an oral history conducted in 2002 by Frederik Nebeker, IEEE History Center, New Brunswick, NJ, USA.

Interview

Interview: Antonio Luque López [referred to as Luque for short]

Interviewer: Frederik Nebeker

Date: 3 July 2002

Place: Madrid, Spain

Family and educational background

Nebeker:

If I could ask first, what was your birth date?

Luque:

I was born on the 15th of August, 1941.

Nebeker:

And where were you born?

Luque:

I was born in Malaga, in the south of Spain. You may have visited there.

Nebeker:

Yes.

Luque:

I am married to Carmen Heredia and I have one son, named Ignacio, and one daughter, Sofia. Both of them are grown. And I have two grandchildren from my son.

Nebeker:

What did your father do for a living?

Luque:

My father was an industrialist. I think inherited some of his interests. In my childhood I read a lot of Jules Verne novels. I was very interested in the feats of the engineers that were able to survive on desert islands and things like that.

Nebeker:

Journey to the Center of the Earth?

Luque:

Journey to the Center of the Earth and Going to the Moon.And then I was convinced I wanted to be what in Spain was called an ingeniero, an engineer. In Spain that was a high-prestige profession. I worked with that intention, but as I told you, my father was an industrialist and I think I inherited from him his interest in creating companies. He was never a very successful industrialist. His success was reasonable.

Nebeker:

What business was he in specifically?

Luque:

He did a lot of things, but when I was very young he started with a factory, which made cardboard packing cartons. Then he made neon signs for advertising. After that he fabricated electrolytic capacitors. He also went into the pharmacy business, which essentially meant mixing the specific drugs to be sold. He made pills that were like a drug for plants that were put into potted plants and very easy to dose.

Nebeker:

A sort of pill-sized fertilizer for plants.

Luque:

Exactly. He became quite successful in that business. That was his history in business in a nutshell.

Nebeker:

Did you grow up in Malaga?

Luque:

Yes, and I went to high school there. When I graduated, thanks to my father's business doing well, I was able to come to Madrid. That was expensive at that time, because my family had to support me. I stayed in a boardinghouse. I think my son, who is also an engineer in telecommunications, has inherited this wish, which was passed to me from my father. He has established his own small company and makes solar trackers and other things related to solar and communications.

Nebeker:

That's very nice. I learned from Professor Vicente Ortega that it was not very common in those days for students from other parts of Spain to come to Madrid to study.

Luque:

Yes. It was expensive for families.

Nebeker:

There was also the limitation in that only a small percentage of students from outside Madrid could study there.

Luque:

Not by regulations as it was the case in the recent past, but yes in the sense that the schools were selective. One had to pass a difficult Concourse for entering.

Nebeker:

Competition?

Luque:

Competition. In the engineering schools it was actually very difficult. In the faculties of science and other areas even those who could give only an average performance on entrance examinations were accepted.

Nebeker:

How did you come to choose engineering?

Luque:

I chose engineering because of my interest in technology in general. Why telecommunications? That was strange at the time. Earlier, because I liked ships and wanted to sail I had planned to become a naval engineer. However in my last year of high school I became an amateur radio operator. I took a correspondence course in radio, and when the moment came to make a selection I decided to go to the School of Telecommunications.

Nebeker:

I see – because of that hobby.

Luque:

Yes, exactly.

Nebeker:

That's very nice. What was it like for you at the school here in Madrid?

Luque:

I belong to a generation that tried to and succeeded in making many changes in Spain. I was very critical. All of the students were very critical with everything. In some cases we had good reasons and in others our reasons were not so good. To become an engineer one had to go to a private academy, a private school, to study mathematics and physics. We had to take a Concourse, a big examination, every year.

Nebeker:

Every year?

Luque:

Every year in June. It was pass or fail, and it was very common not to pass. It was in fact unusual to pass. Then for telecommunications I was lucky in the sense that there were five groups: mathematical analysis, geometry, physics and chemistry, drawing and English. The first three groups were the most difficult, particularly the two in mathematics. I passed the mathematical analysis group in the first year. That was very unusual and really by luck. Therefore I became engaged with this school in the sense that at one given moment after having studied so many months I decided that my real vocation was mathematics rather of engineering. However, once one has chosen a particular path in a prestigious school it is difficult to change one's studies.

Nebeker:

Yes.

Luque:

Therefore I decided I would continue with engineering. I found the school of engineering to be rather uninspiring, however, except for a few personalities. One was Professor Rogelio Segovia – and Vicente Ortega probably talks about this – who was my real mentor. In general the school was ambient and pleasant, but not exciting. Thanks to two or three personalities that were very exciting I became more and more interested. I did a lot of work by the way autodidact. It's probably wrong to say this in the sense that I was in an ambience. The school was not good, but the science was interesting, so we tried to improve the school.

Nebeker:

You and other students?

Luque:

Yes, and a very few of the older professors. Many of the students in my generation were engaged in that. Before that I had already started to do a little. I became interested in a professor's seminar.

Nebeker:

Is this Segovia?

Luque:

Yes. Segovia had a seminar in which we all did experimental work and wrote papers. The first thing he did was to assign us a number of books, all of them in English. It was terrible. I had passed the English exam but knew very little English. In high school I had studied French. I was fluent in French but not in English.

Nebeker:

Did he expect you to read and understand all these English books?

Luque:

Exactly. He forced us to read not just one but two or three. He gave us five or more titles and said, "You have to purchase and read two of these at minimum." It was expensive and terrible, but this is what we did. After the three years I spent for entering this school was five years in duration.

Nebeker:

You spend several years in order to enter the five-year program?

Luque:

Exactly. Of those that started at the same time as me, only one person to my knowledge was ahead of me. The rest of the school was supposed to be five years, but I did it in four years. My father died in the fourth year and I decided I had to accelerate my studies in order to finish more quickly. At that time I was in a university residence. That was an important part of my formation. At that time in Spain some privileged students were living on campus. I was able to get a position on campus. Those of us living on campus were very privileged. We had many professors coming and giving lectures on general cultural aspects. We had a very active intellectual life.

Nebeker:

It was because you were living on campus that it was easy to go to these lectures?

Luque:

They actually came to our residence itself, which was a sort of a center. We had poetry contests for ourselves, for instance, and painting. When my father died they kept me on campus without payment. This was with the understanding that after I finished my studies and became established I would repay them. It was a very non-commercial arrangement.

Lasers and solid-state physics research; doctoral thesis

Nebeker:

Yes. Was this in the early sixties?

Luque:

Yes, this was in something like '64. And then I got my degree in telecommunications engineering. At that time I started to study lasers and later my doctoral thesis was in lasers.

Nebeker:

Why were you interested in lasers, being in telecommunications?

Luque:

That is difficult to say. I am very unusual. I am not a typical telecommunication engineer. In fact, I must confess that I know very little about telecommunications. At that time a professor of electronics was the first to bring the semiconductor technology here that was starting at that time. I think the first visible laser was developed around '61 or something like that.

Nebeker:

I think '61 is correct. Yes.

Luque:

I started to read and study these things in the beginning, probably in '62 or even earlier.

Nebeker:

Was that because you were just interested in it?

Luque:

It was because of my professor. The professor asked us to select a topic among those in current development. I first started with tunnel diodes, but when I saw lasers I thought they were more exciting.

Nebeker:

Did Segovia think that lasers would be important in telecommunications or did he just think it was an exciting new area?

Luque:

He probably thought it was an exciting new area. Lasers were of course considered for telecommunications from the very beginning, so I think he also had viewed this as something that was going to be important in telecommunications, although the laser I fabricated was a ruby laser. It worked in 1966, and I think it was the first laser to be fabricated in Spain.

Nebeker:

I see.

Luque:

This was my doctoral thesis. Before that, I went to France on a Fellowship. After I finished school in Madrid, I spent one year in France making what was called a DEA (Diplôme d’Études Approfondies) on Solid State Physics. I wanted to work in solid-state physics to complete my education in solid state. However I had become very fond of and knew a lot of quantum mechanics,. When I went to France, in general I knew more quantum mechanics than most of my companion students and the professors were surprised at my knowledge of quantum mechanics. Since then I have mostly forgotten it.

Nebeker:

Did you earn a degree in Toulouse?

Luque:

Yes, a degree in solid-state physics. But again, my generation was very critical and when I went to Toulouse I didn't find it very exciting there either. It was more exciting than Spain, but not excellent. The opinions most Spaniards give about Spain are very exaggerated in their negative criticism in general. At least, this is my opinion.

Nebeker:

You expected the University of Toulouse to be more stimulating?

Luque:

Yes. Of course the truth is that at that time the most real hub or center in France was in Paris. The University of Toulouse was second level to that. Of course my criticism was unjust again. I think it was a lack of appreciation on my part and difficulty in adjusting. There were many good people in Toulouse.

Nebeker:

Who did you work with on your doctorate?

Luque:

Officially it was Professor Segovia, but it was really by myself. He was not an expert on this, so I did it. It is very difficult for me to evaluate that work today, because the main characteristic of my education at that time was that didn't have any real frame of reference. When I wrote something I never knew whether it was highly original or something absolutely already known because I did it by myself.

Nebeker:

You were learning on your own then.

Luque:

Yes. I cannot evaluate the real value of my work at that time except that it was pioneering in the sense that I was the first to do what I did in Spain. In France I learned that in the center where I was studying they had tried to make a laser and had failed. And I learned how they had failed. Then I decided I knew how to succeed where they had failed. It was very easy. My optical cavity was probably very bad. The cavity was not going to be very good, but nevertheless if one puts sufficient energy in the flash then the threshold will be reached.

Nebeker:

Yes.

Career as professor

Luque:

I became the Chair Professor of Electronics very early in my career with the support of Professor Segovia. While I was in France, Professor Segovia asked me to come to Madrid to fill a position that was open and reasonable, so I came. It was position as a sort of laboratory teacher. That was among one of the first full-time paid positions in Spain for university teaching. Unless one was very high up it was impossible to get a well-paid position in the university up until that time. Most teaching was done by people working in the industry that came in to teach for part-time hours. And I was among those who started to fight against this view of the university. I became a full professor at a very young age. My thesis was presented in 1967. With my seven years Ingeniero’s degree I was not obliged to have a thesis and was permitted to become a professor. It was much like being considered a doctor. However I wanted to get a Ph.D. by making a thesis and so on, so that was my choice. As I said my research was on the laser.

Nebeker:

From 1967 to '70 you were the laboratory instructor?

Luque:

Well, more than that, I should translate it as assistant professor, and then I became chair professor in 1970. It was a very strong and important position, though I was only twenty-nine years old at that time. To be in a leading position from such a young age has had both positive and negative aspects, but it has been my fate.

Nebeker:

You were teaching this laboratory instruction earlier, of course.

Luque:

Exactly.

Nebeker:

I am sure you had teaching obligations when you became professor.

Luque:

Exactly.

Nebeker:

And you were continued to do research. Is that right?

Luque:

Yes, that's right. At that time a new law was established in which professors were supposed to do both research and teaching. The teaching obligations were actually very little. I have always been free to devote most of my time to research.

Microwave research group and the Laboratory of Semiconductors

Luque:

Two groups appeared in this school. Vicente Ortega belonged to one of these groups.

Nebeker:

Was that the microwave group?

Luque:

Yes, and microwave antennas and electromagnetism in general. That group was led by three people. The eldest was Ricardo Valle. The others were Vicente Ortega and Jesús Sanchez Miñana. This was one of the groups, and the other group formed was my group, which was under the supervision of Segovia, but in practice I was leading it. Since Segovia became director of the school, I was even more in charge of that group. Some years later when Segovia died I became the official leader of that group.

Nebeker:

What was that group called?

Luque:

My group was called Laboratorio de Semiconductores, Laboratory of Semiconductors. This group was created in 1969, the year before I became professor. When Segovia died I was the only one of the young generation in the full professorship that wanted to make a school of research groups – Humboldt School in a way, you see? I applied for director of the school and lost by one vote. I was not happy about that at the time, but that turned out to be good luck for me. This is because if I had succeeded I probably would have become a school administrator. Instead, I have had the career closer to the one I dreamed about when I was a youth.

Nebeker:

That meant that you were able to continue your research.

Luque:

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That's right. I'll tell you how I led my research. Segovia was very ingenuous in the best sense of the word. For instance he said, "If you want something, ask for it." He was so simple. I learned from observing him. He wanted to have a good laboratory, so he asked for it. American money came and he bought an electronics-teaching laboratory that was the best in Spain. It was even famous, because it was one of the first big orders for Hewlett-Packard, with a lot of the original signal generators and oscillators that gave name to the company. There was a signal generator and a oscillator in each of thirty benches. It was something like everything by thirty. From seeing this I learned the value of asking. Therefore I began to ask. With his support I asked for and installed a laboratory of semiconductors in the early seventies. We were laboratory in Spain to be capable of making integrated circuits. There was a company that had technology from National Semiconductors –Piher – that already had some capacity. We got with it our first integrated circuit in something like 1974. I also got enough money to hire ten people or so to form a real team. Many of them are professors here or other schools today, and two of them are still with me.

Nebeker:

Did you establish the Laboratory of Semiconductors in 1974?

Luque:

No, I established the laboratory in '69 and in '74 we were able to make integrated circuits.

Nebeker:

I see. You were able to get the equipment and so on to actually build the integrated circuits in '74.

Luque:

Yes. We asked for the money and when the money came we installed equipment and learned how to make the integrated circuits. When I was in Europe many people were not as advanced as we were. We met with the founder of IMEC (Interuniversiatair Microelectronika Centrum), the big Microelectronic Laboratory in Belgium. You have probably heard of it. He and we worked together. We compared ourselves and we were not so different. He was much more successful than me in establishing a very big laboratory, but I do not envy his commitment because I did not want to create something that big.

Nebeker:

Was your intention just to teach how to design and build integrated circuits?

Luque:

At that time, yes. Then we entered into negotiations with a bank to create a company making semiconductors, making transistors. One person who is still with me, a very fine engineer, Professor Sala made a famous statement in which he basically said, "Well, we are fed up with doing science. We have to make diodes that rectify and transistors that amplify”. Then for one year we'll devote ourselves to making things that work in the market. When we finally tried to make a company to do that it didn't work. At the end we could not convince the venture capitals on how were we going to sell all this. In reality I think it was good. In reality we were ten years late, internationally speaking. However we had at least come to the idea of manufacturing something that would work in the market, and to develop working prototypes.

Nebeker:

Was that unusual for engineering education in Spain to move from the theoretical to actually building?

Luque:

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It was very unusual, and even more so in this technology. It was very expensive. For this reason it was really miraculous that I was able to get money in Franco's time for such a big laboratory. Certainly this was partly due to Segovia's help, but it was also because of what the authorities were looking at that time. They wanted fresh people with new ideas. I think I fit very much with this. People that did not know this secret thought I had some very strong influence with the Franco’s regime. That was not the case. I was against Franco. However I have to tell you that the authorities knew that I was not a supporter of Franco, but Franco felt so secure in his position and was so convinced that he was invulnerable that he tolerated people with views that opposed him. And in fact, he died in his bed. He tolerated people thinking against him. He took the best people he could find, and this was one of the successes of the Spanish transition. For instance, people that became ministers of the Socialist Party had high positions under Franco and were against Franco even while in these high positions. I know this from personal experience. When I was professor I was asked to make a survey of the electronic industry in Spain. We did this by contacting people connected with electronics on telephone lists. We called and asked them what they were doing. We also visited a number of companies. The report we did on that was one of the first reports on the electronic industry in Spain if not the first.

Nebeker:

Was that in the seventies?

Luque:

Yes, it was in '72 or something like that. One day ETA (the today hated terrorist organization) killed the prime minister Carrero Blanco. For leftists this was not an unpopular action at that time. This very day I had to report on the electric industry survey in a government office and what surprised me was that when I went to give my report. I saw the director of this office toasting with champagne. He was toasting and he said, "because today the history of Spain has changed." Can you imagine that? Inside an official building. When people talk about the time of Franco, they often do not realize this aspect. Of course it was a dictatorship. It was not political freedom, but…

Nebeker:

People could still speak their minds.

Luque:

They could speak quite freely. There were a certain number of things one could not do. There was a code. If certain things were done, one would go to jail, but in reality very few things were forbidden. If one knew this code, one could do many things.

Nebeker:

You established that laboratory.

Frontier Science Committee; creation of Institute of Solar Energy

Luque:

After I established that laboratory I was selected to go to the United States to participate in a Frontier Science Committee that was for Spanish-American cooperation. At that time I spoke English very poorly, but I went there in '74 or '75. This was during the time of the first oil crisis and there was much excitement about photovoltaics. I saw that in the United States many of the people doing photovoltaics didn't have the background in microelectronics that I had. Therefore I decided that this was an occasion to get involved with something at its very beginning.

Nebeker:

After this experience of being a little behind with the semiconductors.

Luque:

Yes, because I was ten years late with the semiconductors. And I wanted to try this new thing, so I did. Little by little we changed our orientation, making less and less microelectronics and doing more and more solar energy, and in 1979 the Laboratory of Semiconductors officially became the Institute of Solar Energy.

Nebeker:

Did you influence other professors here to move in that direction?

Luque:

Yes. In my group there were people who did not want to do that. I told those people, "Okay, I will help you to do what you want if you stay here, or you can leave us and start your own business." There was a secession of people from the group, and then we essentially continued with photovoltaics.

Nebeker:

How large was your group at that time, at the beginning, in photovoltaics?

Luque:

At least ten or fifteen people. I am not sure.

Nebeker:

And that consisted a few professors and graduate students?

Luque:

Yes, graduate students working on doctorates. Today we are about fifty people, of which about forty are scientists and the other ten are technicians, administrators and so on. We are about twelve academics two or three post-docs and about twenty-five paid graduate students.

It's not a very big group, although in the beginning it was considered to be very large. Today there are bigger groups in Spain. A bigger group has to be led in a different way, and I don't want to change the form of government we have been using.

Here is a list you can see.

Nebeker:

Was the Solar Energy Institute established in '79?

Luque:

Yes. I think it is explained here.

Nebeker:

The Laboratory of Semiconductors becomes the Institute of Solar Energy in 1979.

Luque:

Exactly. Today I had been tutor of about twenty-six doctorate students. The Institute has formed about sixty doctors in total.

Nebeker:

Did you find it difficult to move into and get started in this new field?

Luque:

My first contact was with a university in the United States that was not very good. As you can imagine, most of the better university groups in the U.S. didn't want to be bothered with a foreign group looking for support. My first partner in the U.S. was Boston College. That is a nice but small college. We started to make evaporated silicon on the stainless steel to see if we could do cheap solar cells this way. They worked very poorly. Then after this experiment, which lasted one year, I decided to go to classic things. Next I went to semiconductor diodes, silicon solar cells.

Invention of the bifacial cell

Luque:

Then my first important invention was the bifacial cell.

Nebeker:

Bifacial cell?

Luque:

Yes. It was a solar cell that was active on both faces. We started an ambitious program that consisted of developing three technologies for doing that. The most obvious technology we worked to develop was one that consisted of making pn junctions on both faces making contact with the junctions themselves and by photolithography to the base, the inner part of the semiconductor. Another technology we worked on developing consisted of making a stack of pn junctions stuck together by heat and cut with saw vertically. This was a technology that we had been working to develop with a factory very high voltage diodes, used for television, and we decided to use that technology for making solar cells. The third technology was the one that, in our opinion, worked best. The previous two did not work because we considered them either too expensive or ineffective. We decided that the best way for a bifacial cells was to make a pn junction in a lowly doped base so that the lifetime would be sufficient to allow the photo-generated carriers near the the rear to reach the front where the pn junction was. And this worked very well. Then we decided to create a company based on this and patented this technology.

Nebeker:

Who do you mean when you say "we"?

Luque:

Me and my group. I invented the concept and the first patent is under my name, but the development was a collective endeavor.

Formation of Isofotón company to market bifacial cells

Nebeker:

Was this is because you saw that you could manufacture and sell this?

Luque:

Exactly. We were wrong, as you will see, but only partly wrong.

Nebeker:

Why did you decide to do that yourselves rather than license it to some manufacturer?

Luque:

First, because I wanted to do it in Spain. There was a certain nationalistic drive to make technology in Spain. Secondly – and this is very definitive – is because I would probably not be considered credible by an American company. My brother and I raised the capital necessary, and we installed this factory in Malaga. We fabricated these cells. The factory contracted and paid the university to pass on the technology. We designed the factory ourselves, with the effort of people in my group.

Nebeker:

What date was this company founded?

Luque:

I think that Isofotón, that is the company’s name, was created in October 1981. I have seen newspaper presentations of the modules already fabricated in 1982. We also supplied 40 this year kilowatts for a plant of 100 kilowatts that was installed near Madrid. This was the brochure of the company. If you like, I can send you a copy of it.

Nebeker:

That would be very nice.

Albedo-collecting module

Luque:

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You see? Isofotón, and this is the module we invented made out of such bifacial cells. It is called albedo-collecting module. This brochure shows both English and Spanish. The first idea was that these bifacial cells were meant for making static concentrators. This is because any concentration of light consists in transforming the narrow cone of light coming from the sun into a wider cone in a smaller area. The product of the area times the solid angle – not exactly the solid angle, but something related with the solid angle – has to be constant. Then with a very narrow cone of rays over a wide surface can be converted it into a wider cone over a smaller surface. The widest cone is not only hemispheric but fully spherical. Therefore, with a photovoltaic converted active in both its sides (the bifacial cell), the concentration would be increased. And we wanted to collect from all of the sky so that no matter where the sun was it could be put into the cell. That was the intention when I invented the solar cell. However we found that the easiest way to do this was just to collect the albedo – the sunlight reflected on the ground. This light is particularly high in snowed surfaces or if the ground in painted on white. Thanks to the bifacial cells, able to covert into electricity the light on the light incident on both the front and the back face, the electric output of such cells was the highest in the market.

Nebeker:

Right.

Luque:

Here is the cell, which is reflected. These are two mirrors, and what you are seeing is the back face and again the front face, so it's bifacial.. We fabricated machines for making panels, modules. How the cells are encapsulated was not our idea but was state of the art. This was a way of measuring this system of cells that were two-sided, and so in order to test them we needed to put the lamps on both faces. This was the first brochure. This symbol was created for us by a company that made the logo for the Iberia Airline. They decided that they wanted to do the logo for us for free because they liked the idea. Therefore we got the logo for free from this very prestigious company.

Nebeker:

Very nice. The sun and the solar panels.

Luque:

Yes.

Funding problems and resignation from Isofotón

Nebeker:

How did the manufacturing and marketing operation work out for Isofotón?

Luque:

It was very difficult. We thought we had the financing necessary to be able to market our product, but in reality this was not true.

Nebeker:

The problem was more in marketing than manufacturing?

Luque:

We had both problems. We discovered that having high manufacturing yields was very difficult. We started to get several important companies, to invest and participate in our company. One company called Abengoa helped us to learn manufacturing. These people helped us to organize the production. Another company that was very important for Isofotón was Alcatel. Alcatel became part owner of the company, had shares, and helped us to sell because Alcatel is a big telecommunication company and they decided to put our panels in their many installations all over the world. We became a preferred vendor for their communications needs. This helped us to make contacts all over the world. But still the company lost money every year because the competitors were big companies: BP Solar today and Siemens, but at that time Arco Solar and others. But finally the company has been able to find its way and today is in the top ten photovoltaic companies in the word. These top ten are listed here. Sharp is the first one; BP Solar is the second one. I can give you a copy of this document. Siemens Solar, Astro Power, RWE – which is a German utility, Isofotón, Sanyo, Mitsubishi and Photowatt. Isofotón is above Sanyo on this list.

Nebeker:

You are the seventh largest?

Luque:

Today, yes. But at that time, in 1989, the company had losses and then, against the wish of the shareholders, I decided to resign as Chairman of the Board.

Nebeker:

Did you have part ownership of the company?

Luque:

No. Unfortunately I sold all my shares at a very low price. It was really a symbolic price at which I sold them. In 1996 the company was bought by a private owner group called Vergés. And then – and this name Vergés can be written – these have been the lucky people that got the company at the moment that the market started to rise quickly. Of course they have been excellent managers and have injected money generously but the company had a very good marketing capacity and excellent fabrication technology. Its cells are among the best cells in the world in regard to efficiency. They are not bifacial today. The bifacial cell manufacturing ceased because people found it difficult to sell this product because of its early publicity. In the beginning we had said, "We sell a product with a higher price per unit but less per watt peak." This turned out not to be a good philosophy and it was decided to go to conventional cells. These conventional cells were based very much in the technology used for the bifacial cells. Today, with the bigger markets imposing the need of making thinner cells they are reconsidering to go to bifacial again.

Nebeker:

You remained president of the company after you resigned?

Concentrator development

Luque:

No. I resigned in 1990, but I still have a very good relationship with Isofotón.

After leaving Isofotón I tried to develop concentrators. We developed a very big concentrator jointly with BP Solar, British Petroleum. The good thing was that I became able to work with several companies. My idea was that concentrators have a very interesting position in the sense that if solar cells are expensive then if one uses optics and concentrates the solar light one might get a better result. This is easy to say, but difficult to do. There are many difficulties encountered in trying to do that. This product is technologically more difficult than a flat panel because one must deal with high light flux and high heat flux and in consequence with high current densities. In addition, the tracking must be fairly accurate. The product was difficult to develop, but we did a full product for BP Solar.

Nebeker:

Was this on a contract basis?

Luque:

Yes. We licensed the technology to BP Solar.

Nebeker:

I see.

Luque:

Before that we won for a partial funding grant from the European Commission and some additional supports. The result was that we were able to install 450 kilowatts of a concentrator in the Island of Tenerife. This may be the biggest or the second biggest in the world for concentrated PV. This proved that we were able to provide a final product.

Nebeker:

I assume that other people were also working on concentrators.

Luque:

Yes.

Nebeker:

But this was particularly successful.

Luque:

We cannot say that. Market and reliability issues still prevent PV concentrators to win a market. But they keep the promise of being cheaper than flat modules.

Nebeker:

But it worked well in that demonstration?

Luque:

It had some reliability problems in the fabrication of the modules. I think these problems can be solved and in fact have been solved. In reality we decided on a plan to make it operate at 800 volts, for a number of reasons. This is very ambitious for most systems. For this system was too much, so we passed to 400 volts. At 400 volts it works well. At 800 volts modules occasionally fail.

Nebeker:

Yes.

Luque:

When that happens it is very difficult to identify the failing module. It took lot of time until we identified the problem. We have done many laboratory tests and actually the reason of the failures is not fully identified. Maybe is combination of heat and electric stress. In theory the materials used should have withstand the 800 volts. For this reason I should not say it is a big achievement. However we learned a lot in the sense that we have been able to do 400 kilowatts. Whether or not to insist in this direction, I don't know because everything has its time. I am sure that reliability problems can be solved but maybe by then a better product can have appeared.

Nebeker:

One of the things one learns in studying the history of technology is that every time there is a new area of technology there are hundreds of attempts and one or two really become known.

Luque:

One or two become successful.

Nebeker:

And one never hears about all these many other avenues that had to be explored.

Luque:

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In reality we are in a situation like that today with concentrators. Several attempts had been made before that in the United States. I think we are the only people working with visibility beyond the United States. Sometimes even some people in the United States think that we are the first, but I don't think they are right about that at all. It's true that we are probably the university group dealing with it most, but in the United States there are several companies working on it. Most of these companies are unsuccessful, but I think that some of them are on the verge of being successful.For a brief period our prototype was considered the leading edge in the United States. This is because BP Solar was behind us, etcetera. However I think the impetus of this approach has been lost today, because BP Solar has not insisted on that. I think the leading companies are Amonix and Entech in the United States.

Multi-junction gallum-arsenide cells

Luque:

However I too am still working on that. I am working now with Isofotón on another concept, and I think this concept might have real possibilities for a serious breakthrough. It has all the components. And that is the following. We are no longer working on silicon cells. We are working on gallium-arsenide cells, III-V cells in general. Why? The reason is that photovoltaics has a fundamental limitation in that it converts properly into electric power only the photons which are very close to the band gap of the material being used. This limitation can be overcome by going to multijunction cells – cells of several materials interconnected. For instance, the largest band gap is on the top of the stack, then the second largest, and so on. Some photons are then collected by the first cell and converted into electricity. Those photons that are not absorbed go to the second cell and are converted effectively there, and so on.

Nebeker:

Yes.

Luque:

In this way in the United States, Spectrolab working jointly with NREL has reached efficiencies 32 to 33 percent with three junctions thus far. There is a tremendous technological effort going in this direction. This is a very beautiful area. However, thus far this has been mostly devoted only to space applications in the United States. I think this can be devoted to terrestrial applications provided one goes to very high concentrations so that only a very small portion of the semiconductor is used. Very little cells. We have proven that we can go to 1000 suns (1000 times the standard solar power on earth, or 1 MW/m2). Formerly this was considered impossible. Today 1000 suns is what everyone is attempting. The reason for this is economic. One of the ways of going to 1000 suns is to make very small cells, so we go to very small cells of 1 mm2. Then we use the encapsulation techniques of photoelectronics, the same as those used for LEDs and lasers. Our concentrators will be manufactured very much like LEDs. We have also developed here some techniques for optical design that are really unique in the world. Our optics group is a very good one and partly funded by joint venturists in the United States and Japan – for other applications of course – and working for optical communications, etcetera. I don't know if you want to hear this. You were talking about history and this is not history. This is modern.

Nebeker:

We're getting right up to your current work, but that's very interesting.

Optic design

Luque:

This optic design is very interesting because our product will be very, very shallow. It will be like a flat panel. It will need tracking, but it will be handled like a flat panel. And one of the things that we will try to avoid is to have too much work to be done on the installation site. One of the things we have learned with Euclides is that everything done out in the field is very difficult to control. The construction workers don't have a sensibility for many things as the manufacturing workers have and it is very easy for mistakes to be made in the field. We want to do things more sensibly now. We want to make things very small and in the factory.

Nebeker:

Yes.

Luque:

In order to control it well. This is what the people in Amonix have discovered also. They are starting to do this in the factory. They are making what they call macro modules, which are assembled entirely in the factory. Then they go with very big parts and put it on the system with a crane. Almost everything has been done in the factory. However we go to a really integrated design.

Nebeker:

Yes.

Luque:

The other thing is, this optic is very special because it allows a very wide acceptance angle in spite of having very high concentration.

Nebeker:

I see. Then the tracking doesn't have to be accurate.

Luque:

The tracking does not have to be accurate. However this optic is very difficult because it also has to be very cheap. We are wrestling with all these commitments and requirements. We need accuracy in making pieces of plastic by injection for instance. We still do not have the product. We think we have to work on that because everything is high tech and the technology of the future. We do make very good cells, but we don't have to manufacture them because if we have the product we can get an agreement with others making the best cells.

Nebeker:

If you prove this concept then you can contract for the best components.

Luque:

Exactly. And everybody will be happy to do a joint venture with us for that. I follow very closely the negotiations of Isofotón. Last year Isofotón's sales were forty-five million Euros. This year they expect to sell eighty million Euros. Now Isofotón is in the position that when they talk to someone in the U.S. or anywhere else, they say, "I want this component." Everyone is very interested in talking with them. The amounts we are talking about are huge.

Collaboration with Isofotón

Nebeker:

What exactly is your relation with Isofotón now?

Luque:

It's only a sentimental relation, but I think they follow what I am doing very closely, and my views.

Nebeker:

Do they fund your research?

Luque:

They fund my research and we work together in applying for funding.

Nebeker:

They are a partner on applications for funding.

Luque:

Exactly. Yes. This is the most common way.

Career achievements

Luque:

Do you want to hear more about my career?

Nebeker:

Yes. Could we look again at your CV? I want to be sure we haven't left out anything important.

Luque:

This is the bifacial solar cell, the EUCLIDES concentrator. Our best efficiency is this little thing. We wanted to prove that we were able to go high in efficiency (we went over 29%). This copy of my CV is a little old. Today I would not include that. I should have put more. This is the intermediate bandgap cell, which is a proposal of a new concept for PV for very high efficiency, based on totally new materials that have to be engineered (maybe with nanotechnology). This was published in Physical Review Letters and is receiving a lot of international attention. Many people are working on it but engineering new materials in only marginally at the reach of today’s technology, although in will be common in ten or twenty years, so today is very difficult.

Nebeker:

I see. To be clear on your professional history, how long have you been director of the Institute of Solar Energy?

Luque:

I have always been director of this Institute. My only career has been this Institute and Isofotón.

Nebeker:

And that hasn't changed. Just to have a little bit of the history of the Institute, you got your own building—

Luque:

Yes, I got this building after many years in a worse place.

Nebeker:

What that in '94? I have forgotten already.

Luque:

The Institute was officially created in '79. Then this building was made in 1994.

Nebeker:

Has the Institute had a gradual growth?

Luque:

Yes, it has been a very gradual growth. Not very fast. In my opinion the groups are very competent now. They are leading in their specialties. However the number of people has not grown tremendously.

Nebeker:

I see. Are you still on the board of directors of the Institute?

Luque:

Yes, I am the chief executive, or in Spanish nomenclature the Director.

Nebeker:

Okay. Vice president of the European Renewable Energy Centres, EUREC Agency.

Luque:

Yes. This is nothing. At the beginning I thought it was very important, but I found it to be essentially just for lobbying . I have received important prizes and awards.

Nebeker:

The National Prize for Technological Research.

Luque:

Yes, this was an important prize from many points of view, including the economic point of view. Another important prize was the Jaime I medal which was awarded to me by a jury in which there were several Nobel Laureates in a jury, among other people. It was this one. Steven Chu laureate in Physics, Elia Prigogine in Chemistry and Werner Arber in Medicine.

Nebeker:

Was a prize for environmental research or technology?

Luque:

Yes, it was for environmental research but I probably got it for technology. Another Nobel Laureate in chemistry, Mario Moreno, in the jury.

Nebeker:

You also won the Becquerel Prize.

Luque:

Yes, this was from the European Commission.

Nebeker:

Okay. You founded the Laboratory of Semiconductors and Institute of Solar Energy (IES). Did you tell me about this plant in Toledo

Luque:

The Institute has six groups. The things I have put on this specific list were not in general my own personal work. The Institute has a group of systems with three types of activities. One type is developing countries. In this respect we have for instance these 1500 stand alone dwellings in Bolivia, then we have photovoltaic grid connected buildings like this one. The third activity is plants. And then among the plants we have installed two. One was the concentration plant in Tenerife but I talked about it before. The plant of Toledo was a 1 MW plant that was not our initiative. The modules there were Spanish BP modules and German Nuken (today RWE) modules, but we participated a lot. For instance we designed dc layout, we performed the quality control for the modules by measuring one out of every ten. The companies got their money according to our measurements, so even though it was a bit difficult for them they accepted it. These sorts of things.

Nebeker:

Isofotón is very much an international company.

Luque:

Absolutely. It sells in forty or fifty countries.

Nebeker:

That's a nice figure. Okay. How is EUCLIDES pronounced?

Luque:

"Oh-clee'dis." It's almost British because we have done it together. This is a Spanish spelling. The British pronounce it as "yu-clee'dis."

Nebeker:

Okay. That was the BP Solar work.

Luque:

Yes.

Economic development and internationalization in Spain

Nebeker:

You have been directing a group here in Spain for many, many years and Spain has undergone very large economic development. It has also undergone many political changes.

Luque:

Yes.

Nebeker:

How has this affected your career? Has it been very disruptive to you?

Luque:

No. Solar energy was a topic that was disturbed very little by these changes, because it has been considered a progressive topic of research. In spite that I was not favorable to Franco I could have been considered a leader of the old situation because I was already chair professor in his times, and thus someone not to be kept. However in Spain we have not had this happen to anyone. I have never suffered that since what I was doing was something that everyone respected. I have not had even a bad year because of revolts. There were moments in Spain with a lot of unrest in the relationships with workers, when everyone was asking for higher pay and so on. I was able to handle all these things very smoothly. I tried to deal with such situations in a way that no one was unhappy. At the same time, because I was not a person that was perceived as someone from the old regime, people did not shout at me or vent hostility in my direction.

Nebeker:

I see. There has also been the change that Spain entered the common market.

Luque:

This has been a very positive change, though there is a negative side to that transition as well. I think that the economy of the country has become very internationalized. Many people think it has become too much so. In some R&D sectors before this international ascension we had a more protected system and industries worked with Spanish centers more effectively and this has been swept out We were actually building a sort of joint industry-research structure that was protected. Some protection at the beginning is good, but cannot be kept forever. This has disappeared. I think probably it has been in the proper time. I have never had a problem with this because I have never been protected. I have always been very internationalized except for my first attempts in making that transistors factory that was ten years too late, and by luck it did not realty start. For the rest I have suffered the same fate as everyone else. All photovoltaic companies have lost money, as I have, so I don't think I have particularly suffered.

Nebeker:

You welcome the increasing internationalization?

Luque:

Absolutely. And of course all my research possibility is based on the European Commission. The Spanish system is a system in which I think the Spanish authorities have not, to my understanding, been able to select areas to promote. Therefore I live essentially from the European Commission.

Nebeker:

I see. You have to get most of your funding from them.

Luque:

Yes, at least half of it. Half of it and the half that shapes the center. There is money coming from Spain, but the one shaping the center is from the European Commission. Today that is half of it, but in the past it has been as much as 70 percent. For me the European Commission has been very important.

Collaboration in the solar energy research field

Nebeker:

What about the field of solar energy in general? Has it always been very international with a good exchange of information?

Luque:

I think so. It's not very large. I am not sure how large it is compared with other fields. We know each other quite well. I think it's a very friendly area where people in general freely exchange information.

Nebeker:

Is research generally published?

Luque:

It's generally published, although of course in some cases you publish more the results than the procedures.

Nebeker:

Are the researchers working for the big companies involved in solar energy publishing their work too?

Luque:

I think so. They don't publish small details that they consider important, but in the present situation there is not one single detail that is terribly important because there are so many considerations. Sometimes when one is just beginning, it is good not to disclose too much too soon. I think it is better to have some achievements with your strategy before disclosing it.

Nebeker:

Yes. I understand. Is there anything I haven't asked about on which you would like to comment?

Commercial predictions for photovoltaics

Luque:

I believe that photovoltaics are going to be a tremendous business. I firmly believe that by the middle of the 21st century an important proportion of the electricity in the world will be photovoltaics. We are trying to prepare for that. This is one general statement I have to make. The second thing I would like to say is that I think more blue-sky research needs to be done. I am involved in some blue-sky work. There is a growing interest in this worldwide.

Nebeker:

Like intermediate band solar cell?

Luque:

Yes. But there is a general interest on new concepts.

Nebeker:

We should have this on the tape that you invented a type of cell. Can you explain that for the layman?

Luque:

Again, the basic idea is that the energy of photons should be better utilized. For that we can revisit something that was suggested by work in the United States in the late fifties. That is having intermediate steps in the middle of the gap so that two photons are used to pump an electron from the valence band, where they lay to the more energetic conduction band using the intermediate band as a relay. This is more effective that relaying on a single photon absorption as present cells do. We are developing this concept today. First we have analyzed the thermodynamic limits of that, which are much better, much higher than conventional cells, and we are trying to engineer new materials with an intermediate band by using nanotechnology in cooperative projects. We only have preliminary results at this time, but we believe that it will be possible to do something with this. We cannot yet evaluate whether or not this will be an important breakthrough, but it's something to explore and it might really be important. We have published many papers on that in good journals.

Nebeker:

Have other people started to look at this?

Luque:

Yes. There are many people looking at this. I am invited to talk on this topic three to four times a year – even without having yet experimental results.

Nebeker:

Other people must think it's exciting as well.

Luque:

Yes, I think many people are looking at these concepts. And that's all I have to say about that. For the moment there are at least some interesting publications. No factories yet. But Isofotón, for instance, is looking at that.

Nebeker:

I see. They're looking at that also. That's a wonderful achievement to have gotten Isofotón going.

Luque:

Yes, indeed.

Nebeker:

Well thank you very much.