Resources | LpR Article | Tech-Talks Bregenz | Light Conversion | Mar 08, 2017

Tech-Talks BREGENZ - Dr. Rubén D. Costa, Group Leader, University of Erlangen-Nuremberg

Light quality and costs of LED systems remain an important topic even though big improvements have been made. New approaches are always welcome and stir up hope. It was exactly a year ago that LED professional published the article by Dr. Rubén D. Costa, Liebig Group Leader at the University of Erlangen-Nuremberg, about his amazing new „Bio-Hybrid“ white LED approach. At LpS 2016 his presentation on the latest research results and improvements also won him the LpS 2016 Scientific Award. Consequently, we just had to invite him to a Tech-Talk Bregenz! In the interview below he gives us some interesting background information about why he started the project, how it works and what he expects in the future. He also gives us his views on LEDs and lighting in general.

LED professional: Congratulations on winning the LpS 2016 Scientific Award. Did it come as a surprise to you?

Rubén D. Costa: First of all, thank you for inviting me for this interview. I would also like to thank the organization for encouraging me to proceed. But to answer your question, I was more interested in the paper and not the award. I think I clicked on the entry button just by chance!

But I was eager to show this technology to the people and compare it and be fair. So my intention wasn’t to win an award, but rather to share the information with the people.

The award was totally unexpected! I was sitting in the last row and had to walk all the way down to the stage. I really appreciate the fact that the paper was found worthy of winning by the advisory board.

LED professional: I read that you were also nominated as a finalist for “The best young chemist in the EU chemistry society”.

Rubén D. Costa: That was very unexpected as well.

LED professional: Was that nomination for the same topic as you entered for the Scientific Award?

Rubén D. Costa: Yes and no. There are different areas for all the young chemists in Europe. If you are under 35 you are considered to be young. But they don’t look at one specific scientific contribution; they look at your whole career. There were 25 finalists and each one only had 10 minutes to show them what they had achieved with their research during their career. I was lucky enough to win the silver medal here. I’m very grateful.

LED professional: If we come back to the LpS Scientific Award, could you tell us a little about how you did your work? Is it more experimental or theoretical? What does your workday look like in the lab?

Rubén D. Costa: It’s a long day. Usually from 7 a.m. to 7 p.m. But the story behind it is that we started working on the hybrid technology because I had material that didn’t work for solar cells and they didn’t work for thin film applications. So I had to ask myself “What can I do with this material?” We thought that if it didn’t work for other things, we should try something different and maybe it would work for hybrid LEDs. And then we made the decision to concentrate on hybrid LEDs. But then I noticed that everyone is doing the same thing. People have been working on this since 1997.

LED professional: So you had to change your plans?

Rubén D. Costa: I have a good friend in the group who is always asking about proteins - he was really keen on “bio”. And I thought to myself, “Bio sounds good and it’s complicated.” So I went to a lecture by a professor from Biochemistry and he was talking about bio staff-proteins. I went to see him and asked him for the material he had and that’s when everything started. I looked at the material, learned from it and then went to the lab and started testing.

LED professional: What have been the challenges working with proteins?

Rubén D. Costa: I began to think that I would have to process the material to be used for technology. But the material is in water and water is terrible for technology. And you can’t work at low temperatures. But you already burn your skin at 100°C - so this temperature is already high for proteins. That was when I realized why nobody was working on proteins. So we had to find a way to stabilize the proteins.

In biochemistry and biology, there are journals that you would never read if you are working in lighting technology. They started to show proteins that can survive x-ray radiation and you start to think, “Oh, this is amazing”. And then you read that there are bacteria in the satellites. And they are outside. And this is also amazing. They are able to go up in space and then down to the earth again, and they are still alive! So you must not think about proteins only but about the whole bacteria. You have to simulate all the bacteria processes that keep it alive. If you take a small piece of the bacteria, it won’t survive, but if you take the whole thing it will live.

LED professional: How did you manage to stabilize the proteins?

Rubén D. Costa: I thought that if a polymer could wrap around the protein, it would stabilize it. We did it, and it worked! But it was a very soft gel. Like a hydrogel. To make it more rigid we looked for a polymer that you can put inside with a very high molecular weight. Interacting with this branch polymer that protects the protein, it turns into rubber.

But I didn’t know whether proteins were still “alive”. So I went to the biochemists and asked them. And they told me that if they had color they were still alive. Because proteins without color are denaturized.

To make a long story short, my students started coating everything with this rubber. They coated spoons and forks and ultimately, Nakamura’s blue LED and we made green, red, orange and all kinds of colors. And then we could make it white. Surprisingly, I noticed that the rubber was always the same color. And after a month it was still alive.

But nobody believed me. Even the core professors of biochemistry thought I was crazy. But I brought them the rubber and I brought them the LEDs because the LEDs were running. It showed that the proteins were stable. In other words, we mimicked the bacteria environment, this cell environment, where the proteins are alive by these artificial polymers.

LED professional: Did you have to manipulate standard proteins for the bio-hybrid LED to become fluorescent or are there natural ones?

Rubén D. Costa: This is the beauty of it: I didn’t need to design anything. Nature did it all for us. There are colors already available for us from blue to red to infrared. Nature provided them a way to communicate with each other. Since they can’t speak, they use their colors. It started a long time ago when a scientist got stung by a jellyfish. Despite the pain, he noticed that the jellyfish was green and he wondered why and how it could be. And then they discovered a protein - called the Green Fluorescent Protein. There are other proteins with funny names like, Tomato, Zucchini, Papaya and Cherry!

LED professional: So in the future we won’t have to buy a 435 nm LED; instead we’ll buy a Zucchini LED!

Rubén D. Costa: Yes! Nature has provided us with everything.

LED professional: On a more serious note: If we talk about the conversion efficiency of proteins - is it comparable to the phosphors that are used in conventional white LEDs?

Rubén D. Costa: It depends on the protein. The green fluorescent are working, yes - conversion of blue LED light is quite high, actually. The red is a problem we still have to solve. What nature didn’t think about are high quantum yields. But if we have bacteria with a genetic code, (I’m not saying that we can do it right now), I can think about modifying things in order to make the chromophore more stable and lock it in my protein or make the protein more efficient in emitting light. Once you have this, production is easy. It’s just two bacteria and it’s going very nicely.

LED professional: So the major issue now is lasting stability, especially when it’s exposed to the higher temperatures of the LED.

Rubén D. Costa: Exactly. Today, one of the challenges that we have is high power LEDs. If you ask me if we can use high power LEDs with proteins today I would honestly have to say no. The reason is because the temperatures are very high. We can reach temperatures of over 200°. Phosphors can cope with this because they are inorganic but proteins can only cope with about 120°. If you pour boiling water on proteins, nothing will happen. You can heat these rubbers to 150° and depending on the protein design, it can survive. These temperatures are upper level because the well-known proteins are stable. For high power LEDs we still have to design appropriate proteins.

Dr. Costa presented the research results of his team from the University of Erlangen- Nuremberg (FAU) at the LpS 2016

LED professional: If I remember correctly, in one of our first conversations you mentioned that mass production of these conversion protein systems with the rubber could be cheaper than the production of phosphors today.

Rubén D. Costa: Absolutely. We have to remember that phosphors are always located in mines in very specific places in the walls. You have to mine them, transport them and then process them. It is very expensive and the consumer pays for it. You also have to realize that it is a mine, and sooner or later there won’t be anything left in it. But in the case of the proteins, you can produce them from the E-coli. It’s a well-known bacteria; one that everybody can use. When I say everybody, I mean you - in your home, people in China, America, Brazil and Africa - can produce the bacteria and the genetic codes. Once you have them, and they are free, anybody can produce them. The good thing about the bacteria is - you put half of the sugar in your coffee and the other half you give to the bacteria. And while you drink your coffee, the bacteria grow. OK - you do have to give them other things like amino acids, but really, what you have to give them costs next to nothing.

You grow them and they multiply. You kill half of them and take the proteins and in the meantime the other half is growing and multiplying. If you keep this going, production is extremely inexpensive. If you want a super highly purified protein to inject into a mouse or even a person, you will pay up to 200 Euros but the question is: Do we really need 99.9% purified protein for an LED? In my opinion the answer is no. So if you reduce the purity requirements the price will drop dramatically because purification is one of the most expensive parts of protein production.

Once we discover what level of purity is optimal for the LED, we will be able to calculate the cost.

The status of current "Bio-Hybrid" white LEDs was presented during LpS 2016: A cascaded RGB protein coating on blue LEDs results in white LEDs with approx. 50-90 lm/W and CRI 75-80. The graphs on the right side show the degradation of the three proteins and the efficiency decay over time

LED professional: You mentioned that improvement for the red color is necessary. How do you think you could do that? Would you look to nature to find other proteins that have the right characteristics or would you try to artificially manipulate the proteins to change their characteristics?

Rubén D. Costa: I would go in both directions. On the one hand, looking at nature and taking different red florescent proteins is easy. It’s cheap and only a matter of one, two or three months and then test them. On the other hand, that’s not a very scientific way to take everything we have and test it. But it’s good to learn. Therefore, when you collect the information that we already have, you know we have this protein and it’s running and it might be better than the one we usually use. Now we have to find out why it’s better and how is this protein interacting with my rubber to understand it because maybe it works better because it interacts better - not because nature made something better. And then I have to find out how I can modify my matrix so that the other ones interact better. And then, we understand this manifold of data; it’s the moment that we can start thinking about engineering the product. How can I make my protein interact better with my rubber? Or how can I make it have high quantum yields. Bacteria can produce a lot of artificial proteins but Mother Nature never used it because she doesn’t need to.

One of the latest trends in manufacturing LEDs is the emulation of sunlight at different CCT’s. This is also possible with Bio- Hybrid white LEDs due to the high number of colors already available from fluorescent proteins

LED professional: Technology is often not seen objectively. At the moment, biotechnology and genetic modifications and so on, are not liked very much. So I’m wondering if people will start to worry about you changing the genome of the bacteria and think what you’re doing is dangerous.

Rubén D. Costa: I have two things to say to that: E-coli is in our stomach. When you get sick you have lost them. We need them. We need the symbiosis with them. E-coli is also a very stupid bacterium. If it doesn’t have food, it dies. If you take it out of the lab environment, it dies. We have known about E-coli since the beginning of the last century and have used it to produce natural proteins. There is nothing new about it. When you think about artificial proteins, they are florescent proteins - we aren’t creating any viruses or producing super bacteria that will cause people to turn green. So I have to say that it isn’t harmful. And there is nothing harmful coming from these rubbers.

LED professional: If you look at the technology in the future and everything runs smoothly, how long would it take to make this type of technology mature?

Rubén D. Costa: If we start with a hundred hours of stability, which is 4 or 5 days then we stop it because we compare it to the state-of-the-art. We are scientists but we also have to think about publications. Today we have started to understand stability is in the range of months. We have to look at the application. Where is it going to be applied? I don’t think it will be used for outdoor luminaires. This will take years. If we are lucky and everything runs nicely, we can say which application needs which protein in 4 to 5 years. That’s my dream - my goal.

What we have today is more for indoor activities or interior car lighting. So I think that it is possible to use our technology for smart lighting. These are applications that don’t require a very long lifetime or high luminescence - so we can think about these things. Depending on the money and the manpower, I think we can fulfill all the examples I have given within a short time. But to cover the whole lighting technology on a broad basis will take us 5 to 10 years. I can’t predict exactly when but I can tell you that we have made a lot of progress with this technology and we can propose new things.

On the other hand, I like to sit down with the people from the industry and let them tell me what they want. I think about stability - 100,000 hours of stability and I sit down with someone who wonders why we would need that many hours of stability. We will die before the LED does! And it’s true. But - everybody wants to have that big number.

What I want is for the person to give me their problem and I will try to figure out how to solve it using the knowledge I have. If you give me the application I will look for the right protein and the right structure. Today it depends on the time, the money and the motivation.

LED professional: If we talk about money: Is your work already funded? Will the Scientific Award help towards getting funding?

Rubén D. Costa: By giving me this award you have shown me that you read the paper and thought that this is a possible new technology. It shows me that you trust me and I will try to live up to this trust. And I think that if people see that the advisory board has put their trust in me, it will help us to get funding. The award supports my work and I truly appreciate it. It encourages me to continue with my work.

LED professional: As a last question I was wondering what you thought of the LpS program? Was there something there for you, as a scientist?

Rubén D. Costa: It was fantastic being able to meet with so many different people and have good conversations. The exhibition was very interesting for me as well. I walked through it several times because I wanted to see everything. The industrial lectures were interesting in that they would look at a problem and try to solve it. I learned quite a lot. My philosophy is to go to an event with an empty box and when I leave the box has to be full: Full of business cards and full of ideas. So in this sense the program was very interesting. I really enjoyed it. The scientific lectures were great because I could see the science behind the questions. The mixture of the industrial and scientific lectures was good. My students will be very busy next week when I throw all these new ideas at them!

LED professional: Thank you very much for your time.

Rubén D. Costa: My pleasure.

Dr. Rubén D. Costa
He received his Ph.D. on the design of ionic transition-metal complexes for thin-film lighting sources at the Institute of Molecular Science in 2010 (Valencia). He was a Humboldt Postdoc at the University of Erlangen-Nuremberg (Germany) from 2011 to 2013, working on nanocarbon-based solar cells, and has had the position of Junior Group Leader there since 2013. His current research interest concerns the design of new hybrid materials (i.e. organic/ norganic as well as bio-hybrid components) and their utilization in thin-film optoelectronics, in which he is considered a well-established, young researcher. This is supported by the h-index of 28 and the number of citations (>2300), publications (>80), and 19 awards/scholarships.

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