- The team you lead has recently filed two patent applications. They concern an idea that could revolutionise our approach to photovoltaics.
- Our latest two patent applications relate to a method of making graphene quantum dots. We want to use them to build transparent and flexible photovoltaic cells, we will be able to stick them on the glass of high-rise buildings, for example. Their significant advantage is that they are silicon-free.
- How did the idea come about?
- This is the result of a confluence of different circumstances. A year ago, we looked at how to reduce the cost of photovoltaic cells. In an international team, because we had students from Ecuador, Norway and Belgium with us at the time, together with Piotr Zawadzki, Ph.D., and our doctoral candidate Piotr Kosobudzki, we started to think about whether we could use graphene. And if graphene, in what form? It turned out that these would be graphene quantum dots. Above all, we wanted them to be cheap and efficient to produce, as we did not have the equipment for this process at the time. After analysis, we opted for the microwave method. We wondered where to get the carbon substrate that our dots are made of. We chose organic materials, i.e. fruit and vegetables, such as bananas, beetroot, oranges, etc.
- This is a very tasty idea...
- What's more, it has emerged that we can produce quantum dots using devices that most of us have in the...kitchen. We are currently running this process at high capacity. It was supposed to be cheap! Recently, we used grass collected in the garden for synthesis. As you can see, we can still make money from this process by collecting bio waste, which we will then use.
- Can we, without, of course, going into detail, find out how the process of quantum dot synthesis takes place?
- First of all, we have to make an extract out of the organic products, i.e. pre-process them to a pulp-like consistency. This pulp is then put into... the microwave, and after half an hour, we obtain suspensions of quantum dots. They can be seen under a microscope but should also shine under UV light. Now we take another device, a UV lamp used e.g. in a beauty salon, and check that the extract has a coloured glow, this can range from green to a delicate yellow to blue. Of course, later on we do sublime studies, using a TEM (transmission electron microscope) to see what kind of systems we have, because we can already see them. The most important thing now is to extract these quantum dots from solution, and they are up to 10 nanometres in size. We have already developed a method. We transfer the resulting graphene quantum dots onto foil using an atomisation effect, i.e. ... like that of a perfume bottle, and make them into electrodes. We have it all calculated, we know how many dots will be released at a given force, distance etc. We get the percolation effect (the process of leaching/precipitation of substances from the substrate) and can convert solar energy into electricity. This is the process in a nutshell. What is most important is that a method for the microwave synthesis of graphene quantum dots and a prototype photovoltaic cell has been developed at Lodz University of Technology.
- Please highlight the main elements of the innovation of the idea.
- Graphene quantum dots were produced from bio-waste, but mainly by a hydrothermal method, whereas we used a microwave method, which we modified. This ensures that the quantum dots we synthesise are virtually the same size. We also have a much higher process efficiency due to the fact that we have modified the device itself, which is the subject of a patent. As such, we are not discovering a new thing, but modifying what was there and trying to scale it up for industrial applications.
- How are you going to use the patented ideas?
- We want to set up a spin-off company and produce films with graphene quantum dots applied to them. For this, we need to find a balance between the thickness and strength of the film, so that it is not subject to microcracks - because at this stage of the research this is irrelevant.
At the moment we have a prototype that works. The next stage is to scale it up to a larger film and make professional electronics to see how it works overtime, whether the energy conversion parameters change.
It is still too early for a business plan. We think that with mass production the costs will be low and that was our assumption. We are looking for investors, but I am positive here. Why? Firstly because, in the case of silicon cells, we do not know the price we will have to pay for them in a year's time. Secondly, there is the problem of integrating them into the roof, there has to be adequate sunlight, and this problem does not exist when the cells are on films that we can stick or incorporate into the windows or the facades of the building. What is further worth emphasising is that graphene quantum dots are made of carbon and are therefore safe for human health.
- Finally, please introduce the authors of patents related to the synthesis of graphene quantum dots.
- The co-authors of the patents are international students: Diana Ramos from Yachay Tech University in Ecuador, Anders Garuud and Maria Barfod from the Norwegian University of Science and Technology and Esther Simoen from Ghent University in Belgium. Another is Piotr Zawadzki, Ph.D., who is working on the topic of graphene quantum dot synthesis in his habilitation thesis in preparation. Also co-authoring patents is Piotr Kosobudzki, who is working on a transparent photovoltaic cell using graphene quantum dots in his PhD.