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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 cardiologists and surgeons give children a beating heart
2015-04-23

Photo: René-Jean van der Berg

A team from the University of the Free State School for Medicine work daily unremittingly to save the lives of young children who have been born with heart defects by carrying out highly specialised interventions and operations on them. These operations, which are nowadays performed more and more frequently by cardiologists from the UFS School of Medicine, place the UFS on a similar footing to world-class cardiology and cardio-thoracic units.

One of the children is seven-month-old Montsheng Ketso who recently underwent a major heart operation to keep the left ventricle of her heart going artificially.

Montsheng was born with a rare, serious defect of the coronary artery, preventing the left ventricle from receiving enough blood to pump to the rest of the body.

This means that the heart muscle can suffer damage because these children essentially experience a heart attack at a very young age.

In a healthy heart, the left ventricle receives oxygenated blood from the left atrium. Then the left ventricle pumps this oxygen-rich blood to the aorta whence it flows to the rest of the body. The heart muscle normally receives blood supply from the oxygenated aorta blood, which in this case cannot happen.

Photo: René-Jean van der Berg

“She was very ill. I thought my baby was going to die,” says Mrs Bonizele Ketso, Montsheng’s mother.

She says that Montsheng became sick early in February, and she thought initially it was a tight chest or a cold. After a doctor examined and treated her baby, Montsheng still remained constantly ill, so the doctor referred her to Prof Stephen Brown, paediatric cardiologist at the UFS and attached to Universitas Hospital.

Here, Prof Brown immediately got his skilled team together as quickly as possible to diagnose the condition in order to operate on Montsheng.

During the operation, the blood flow was restored, but since Montsheng’s heart muscle was seriously damaged, the heart was unable to contract at the end of the operation. Then she was coupled to a heart-lung machine to allow the heart to rest and give the heart muscle chance to recover. The entire team of technologists and the dedicated anaesthetist, Dr Edwin Turton, kept a vigil day and night for several days.

Prof Francis Smit, chief specialist at the UFS Department of Cardiothoracic Surgery, explains that without this operation Montsheng would not have been able to celebrate her first birthday.

“After the surgery, these children can reach adulthood without further operations. Within two to three months after the operation, she will have a normal active life, although for about six months she will still use medication. Thereafter, she will be tiptop and shortly learn to crawl and walk.”

Mrs Ketso is looking forward enormously to seeing her daughter stand up and take her first steps. A dream which she thought would never come true.    

“Write there that I really love these doctors.”

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