[Apr. 15, 2023: JJ Shavit, The Brighter Side of News]
Most solar cells are currently silicon based; However, their efficiency is limited. (Credit: Creative Commons)
Researchers at Martin Luther University Halle-Wittenberg (MLU) have discovered a new method to increase the efficiency of solar cells by a factor of 1,000. The team of scientists achieved this breakthrough by creating crystalline layers of barium titanate, strontium titanate, and calcium titanate, which were alternately placed on top of each other in a lattice structure.
Their findings, which could revolutionize the solar power industry, were recently published in the journal Science Advances.
Solar cells currently in use are mostly silicon-based, but their efficiency is limited. This has prompted researchers to explore new materials, such as ferroelectrics such as barium titanate, which is a mixed oxide composed of barium and titanium. Ferroelectric materials have spatially separated positive and negative charges, which leads to an asymmetric structure that generates electricity from light. Unlike silicon, ferroelectric crystals do not require a PN junction to create a photovoltaic effect, making solar panels easier to manufacture.
However, pure barium titanate does not absorb much sunlight, resulting in a relatively low photocurrent. New research has shown that combining extremely thin layers of different materials significantly increases solar power yield.
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According to physicist Dr. Akash Bhatnagar of MLU’s Center for Innovation Competence Sily-Nano, “The important thing here is that a ferroelectric material is alternated with a paraelectric material. Although the latter do not have different charges , it can become ferroelectric under certain conditions, for example at low temperatures or when its chemical composition is slightly altered.”
Bhatnagar’s research group found that the photovoltaic effect is greatly enhanced if the ferroelectric layer alternates with not just one but two different paraelectric layers.
Yeesul Yun, PhD student at MLU and first author of the study, explained the process involved: “We embedded barium titanate between strontium titanate and calcium titanate. This was done by vaporizing the crystal with a high-power laser and was achieved by re-depositing them on carrier substrates. This produced a material made up of 500 layers that are about 200 nanometers thick.
For their new approach, the researchers combined three crystal materials. (Credit: Yuni Halle / Yeseul Yoon)
While performing photoelectric measurements, the new material was irradiated with laser light. The result surprised even the research group: compared to pure barium titanate of a similar thickness, the current flow was 1,000 times stronger, despite the fact that the proportion of barium titanate as the main photoelectric component was reduced by about two-thirds Was.
“The interactions between the lattice layers lead to a much higher permittivityin other words, electrons are able to flow more easily due to excitation by light photons,” explained Bhatnagar. The measurements also showed that this effect is very strong: it remained almost constant over a period of six months.
Structural characterization of superlattices. (A) Cross-sectional STEM obtained from specimen SBC222. (b) High-resolution STEM from a portion of the scanned area. The arrangement of unit cells is shown in the diagram. RSM obtained around (103) images in (C) BTO, (D) SBC555, (E) SBC252, and (F) SBC222. The star and yellow arrows indicate satellite peaks from the STO substrate and SL, respectively. (Credit: Yuni Halle / Yeseul Yoon)
Further research is now necessary to determine the exact reason for the outstanding photoelectric effect. Bhatnagar is confident that the potential demonstrated by the new concept can be harnessed for practical applications in solar panels. “The flake structure shows higher yields in all temperature ranges than pure ferroelectrics. The crystals are also significantly more durable and do not require special packaging.”
This new development has far-reaching implications for the solar industry. Solar panels made from this new material would be significantly more efficient, and their production cost would be lower than that of silicon-based solar cells. In addition, they will require less space to generate the same amount of power, making them ideal for use in urban areas where space is limited.
The MLU research team’s discovery has already attracted the attention of industry leaders. Dr. Jennifer Rupp, a professor at ETH Zurich who was not involved in the study, commented on the significance of the findings. “This is a very exciting discovery that could have a significant impact on the development of more efficient solar cells,” Roop said. “The fact that the new material is more durable and easier to produce than conventional silicon-based solar panels makes it even more promising.”
Enhancement of photovoltaic effect in tricolor superlattices. (a) Current-voltage (I-V) characteristics measured with 3.06 eV at room temperature. (B) Current time response acquired with the lights on and off. (Credit: Science Advances)
Solar power is one of the fastest growing sources of renewable energy, and the demand for solar panels is expected to increase dramatically in the coming years. According to the International Energy Agency, solar power is set to become the largest source of electricity by 2050, accounting for about one-third of global electricity generation. However, the efficiency of current solar panels needs to be improved if this is to become a reality.
The MLU research team’s discovery could play a key role in this change. By enhancing the photovoltaic effect of ferroelectric crystals, the new material could greatly increase the efficiency of solar panels. This will not only make solar power more cost-effective but also reduce our dependence on fossil fuels and help combat climate change.
The study’s lead author, Yeseul Yoon, is excited about the potential impact of the team’s findings. “Our discovery opens up a new avenue for the development of more efficient solar cells,” Yoon said. By combining different materials in a specific way, we can create a material that generates much more electricity than conventional silicon-based solar panels. This could revolutionize the solar industry and help us transition to a more sustainable future. I can help.”
The next step for the MLU research team is to further investigate the properties of the new material and optimize its performance. “We are still trying to understand how the different materials interact to produce such a strong photovoltaic effect,” Bhatnagar said. “We also want to see if we can further increase the efficiency of the material by changing its composition or structure.”
The team is already working on a new prototype solar cell based on their findings. If successful, this could lead to the development of commercial solar panels based on the new material within the next few years. “We are excited about the potential of our discovery to make a real difference in the world,” Yun said. “If we can make solar panels that are more efficient, durable and cost-effective, we can help accelerate the transition to a more sustainable future.”
The findings of the MLU research team have also generated interest among investors and entrepreneurs. Several start-ups are already exploring ways to commercialize the new technology, and venture capitalists are eager to fund further research in this area. “It’s a very promising area with a lot of potential,” said Markus Ederer, CEO of a renewable energy start-up based in Berlin. “If we can make solar panels more efficient and cost-effective, we could transform the energy sector and help tackle one of the biggest challenges facing humanity today.”
The MLU research team’s discovery is just one example of the groundbreaking research being done in the field of renewable energy. With the world facing urgent environmental challenges, it is more important than ever to invest in clean energy technologies that can help us transition to a more sustainable future. By harnessing the power of the sun, we can reduce our carbon footprint and create a more prosperous and equitable world for generations to come.
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