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01 March 2024 | Story Leonie Bolleurs | Photo SUPPLIED
Dr Lucas Erasmus
Dr Lucas Erasmus, Junior Researcher in the Department of Physics, has just returned from Belgium where he had his public defence of a joint PhD with Ghent University, titled: Luminescent solar concentrators – where Sm2+ doped phosphors shine.

“I like taking what I have learned from literature and going to the laboratory to test it. Sometimes the results surprise me, leading to additional experiments or refining. This process could continue for several months and even years, with me slowly building the puzzle. And finally, one day, all the pieces come together, and everything becomes very clear to me as a physicist. And if I am lucky, I will have the privilege of knowing a secret about nature that nobody else has known up to this point. However, as an innovator, I am tasked with using this new knowledge to develop ways to manipulate nature to deliver a helpful device.”

These are the thoughts of Dr Lucas Erasmus, Junior Researcher in the Department of Physics at the University of the Free State (UFS), who has just returned from Ghent, Belgium, where he had his public defence of a joint PhD with Ghent University, titled: Luminescent solar concentrators – where Sm2+ doped phosphors shine.

The research project is part of a bilateral collaboration between the Department of Physics at the UFS and the Department of Solid State Sciences at Ghent University. In this study, the strengths, experience, and resources of both research groups – experienced in developing luminescent materials for various applications – are used to ensure a stronger final product. To meet the requirements stipulated in the cooperation agreement between the two institutions for the joint supervision and certification of Dr Erasmus’ doctoral studies, research was conducted both at the UFS and at Ghent University.

Dr Erasmus’ research is significant in the light of rising energy prices, energy scarcity, and the pursuit of a carbon-free society, where there are strong incentives to develop new and renewable energy sources.

Combining windows and solar cells increase their relevancy in many applications

He says that although solar panels play an essential role in renewable energy – since they provide a route to directly convert solar radiation into electricity – there are limitations to installing conventional panels, which are bulky, rigid, and opaque. He believes that combining windows and solar cells could increase their relevance in the built environment, agricultural sector, and modern consumer electronics.

Explaining about the luminescent solar concentrator (LSC) in his study, he states that it is a device used as a large-area solar radiation collector that converts and emits radiation. The emitted radiation is directed to photovoltaic cells located in the small side area of the device. According to him, a basic LSC consists of a transparent waveguide with an embedded luminescent material and a strategically placed photovoltaic cell on the edge.

Dr Erasmus continues, “The large area of the waveguide collects a portion of the solar radiation, while the luminescent material absorbs the energy and downshifts it to longer wavelengths. Internal reflection directs the emitted photons towards smaller areas on the sides where the photovoltaic cells are used to convert the concentrated light into electricity.”

In his view, creating a large and efficient LSC is a challenging endeavour that requires an in-depth study of multiple domains. “This includes developing and optimising the luminescent material, studying its behaviour and the characteristics of the waveguide, and finally adding these two components and developing, characterising, and simulating the hybrid device,” he remarks.

“While the current prototype we have developed delivers good results, it is still far from perfect and not commercially viable,” he says, stating that this study could, however, serve as a guide for future researchers interested in developing LCSs. Dr Erasmus believes the underlying science behind the results contributes to a general understanding of the materials, making this study valuable to other fields and contributing to the larger body of science. At the end of the study, he also makes some recommendations for future research in this field. 

Study a reflection of theoretical knowledge and a practical system

The public defence consisted of both an internal and an external defence. The internal defence took place in January at the UFS between Dr Erasmus and the examination committee. The external defence occurred at Ghent University and was also open to the broader public. Also present at this event in Belgium were colleagues from the UFS – Prof David Motaung, an examiner; Prof Koos Terblans, co-supervisor; and Prof Hendrik Swart, supervisor for the PhD thesis.

Dr Erasmus’ experience of the oral examination was that the examiners were primarily positive in their critique but also thorough in their questioning. According to him, some of their remarks pointed out that they were impressed with the meticulous planning, execution, and interpretation of the experimental results and that the researchers involved ensured that any parameter that might have influenced the device was maximised. “Moreover, they liked the fact that I went all the way from theoretical knowledge to a practical system. The examiners also noted that the study compares well with the current state-of-the-art research in the field,” adds Dr Erasmus.

He says that having the public defence in Belgium was a once-in-a-lifetime experience, allowing him to interact and deliberate directly with the examiners and communicate their findings and conclusions to the broader public. Dr Erasmus hopes that this will lead to stronger collaboration and better public sentiment toward spending funding for scientific projects.

For future steps, he states, the research group involved in the project plans to continue this research by further increasing the device's efficiency. “To this end, we have already developed another luminescent material that can address some of the challenges we encountered while developing the first prototype device. This forms part of the work that Johané Odendaal is doing in her master’s degree, of which I am a co-supervisor. We also plan to enlarge the scope of our research to consider the challenges that are currently hampering the next generation of photovoltaic cells and to find ways in which we could address these issues,” comments Dr Erasmus.

News Archive

UFS alumnus receives PhD in Statistics from the University of Oxford
2016-06-03

Description: DW Bester  Tags: DW Bester

In May of this year, DW Bester obtained
a DPhil in Statistics at the University of
Oxford.
Photo: Supplied

On 14 May this year, Dr DW Bester received a DPhil in Statistics from the University of Oxford. The entire ceremony, which was held in the Sheldonian Theatre in Oxford, was conducted in Latin, as has been the case for the past 800 years.

Dr Bester completed his undergraduate studies and his honours degree at the University of the Free State (UFS). “At first, I was only planning to study for a master’s degree, but was privileged to get an opportunity to do a PhD as well. I didn’t think twice!” he says.

Studies at the University of Oxford


Universities in England do not require a master’s degree for PhD studies. With the help of Prof Max Finkelstein from the UFS Department of Mathematical Statistics and Actuarial Science, Dr Bester registered for the DPhil programme in Statistics directly after his honours studies.

“The title of my thesis was: Joint survival models: A Bayesian investigation of longitudinal volatility. It dealt with a problem in the medical field to determine the cause of stroke risk: is it the absolute level of blood pressure, or the volatility thereof? The analysis of this question led to interesting models which needed advanced application techniques. I had to study these techniques and write programmes for their application.

Although Dr Bester is working currently as the technical head of a company that calculates insurance for power stations, satellites, rockets, and cyber risks, he would like to continue working with his Oxford supervisor in future to make the techniques they have developed more accessible for researchers outside of the field of statistics.
 
“Studying at Oxford requires hard work, perseverance, and a lot of luck. Luck plays a big role, since there are no guarantees that hard work will ensure you a spot in one of the top universities.

Regarding his studies at Oxford, Dr Bester thinks back on his exposure to the GNU/Linux operating system, and free software. “I have seen how valuable this is for analyses in practice. I also had the privilege of meeting the father of free software, Richard Stallman,” Dr Bester says.

2011 Rhodes Scholar

He was elected as Rhodes Scholar in 2011. According to Dr Bester, who has been interested in Mathematics since high school, the Rhodes scholarship was something of a fluke. He applied for the Rhodes scholarship on the recommendation of Prof Robert Schall of the Department of Mathematical Statistics and Actuarial Science.

Role of the UFS in his successes


In addition to the continued support from the team of passionate professors and lecturers at the UFS, the actuarial degree at the UFS is fraught with statistics. Emphasis is also placed on Bayesian statistics. This was crucial to his studies at Oxford. According to Dr Bester, this topic is emphasised strongly in the international statistics community.

Dr Bester regards the work done by two of his lecturers, Michael von Maltitz and Sean van der Merwe, among his highlights at the UFS. Since our first year, they have created an atmosphere of camaraderie among the students. “I think this contributed to the success of everybody. They also make an effort to present topics outside of the syllabus regularly,” says Bester.

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