A team from Martin Luther University Halle-Wittenberg (MLU) has taken an important step in the search for solar cells. The combination of three crystal layers greatly increases the photovoltaic effect: by a factor of 1000. It can make photovoltaic systems more efficient.
If the energy transition is to succeed, rapid expansion is necessary Renewable energy Necessary. Systems that generate electricity from renewable energies more efficiently are a crucial help. No wonder there is so much research in this area. A team of researchers from Martin Luther University Halle-Wittenberg was also looking at the efficiency of solar modules for a significant increase. They have now made a breakthrough with a mixture of different crystals: they were able to use the so-called light effect Increase by a factor of 1000.
Who discovered the photoelectric effect?
The photoelectric effect converts sunlight into electricity. It was discovered more than 150 years ago. Physicist Edmund Alexander Becquerel succeeded in this transformation for the first time in 1839, which was then used primarily in photography to measure exposure.
Becquerel experimented with electrolytic cells in which he used the anode and cathode made of platinum. It can measure the current flowing between these electrodes. He found that the current was slightly larger in the light than in the dark. Basis PV Discover.
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More efficient solar cells thanks to the photovoltaic effect with ferroelectric
Silicon is currently the most widely used material in the construction of solar cells. Disadvantage: the efficiency of silicon is limited. This is why research has been looking for alternatives for a number of years. Researchers are currently focusing on materials such as barium titanate, a mixed mixture of barium oxide and titanium. These materials belong to the group of so-called ferroelectrics. “Viroelectric energy means that a material has positive and negative charges that are spatially separated,” says Akash Bhatnagar, a physicist at the SiLi-nano Innovation Efficiency Center at MLU.
The demand for solar energy is increasing more than ever
“The charge separation leads to an asymmetric structure that enables electricity to be generated under light,” the physicist explains.
Since hydroelectric crystals do not require the so-called pn junction for the photovoltaic effect, that is, there are no positive or negative doped layers, this can make the production of solar modules considerably easier. On the other hand, silicon needs this p-n junction.
Changing materials to make solar cells more efficient
However, pure barium titanate also has a certain drawback: it absorbs little sunlight, and therefore naturally produces a low luminous flux by comparison. That’s why the research group tried a bunch of different materials. The result: makes it possible to get more energy from the sun. “It is important that a ferroelectric material alternates with a semi-electric material. Although the latter does not have discrete charges, it can become ferroelectric under certain conditions, such as low temperatures or slight modifications in chemical composition,” Akash reports. Bhatnagar.
As part of their tests, it has now been shown that the photovoltaic effect can be particularly improved if the ferroelectric layer is combined not with just one, but with two different alternating quasi-photovoltaic layers. “We combined barium titanate between strontium and calcium titanate. To do this, the crystals are evaporated using a high-performance laser and deposited back onto the carriers. The materials produced in this way consist of 500 layers and are about 200 nanometers thick,” explains Yeseuk Yun, a student PhD at MLU and first author of the study.
The current flow in the solar cells increased by up to 1000 times
The researchers tested their physical composition with laser light. They were surprised by the result themselves. The current flow was up to 1,000 times stronger than measurements made with pure barium titanate. With the combination of the new materials, the scientists reduced the proportion of barium titanate as the main photovoltaic fraction by nearly a third. “It is clear that the interaction of the lattice layers leads to a significantly higher permittivity – that is, to the fact that electrons can flow away more easily due to the excitation of optical photons,” says Patanyar. And that’s not all: the researchers tested their new mixture of substances over a period of six months. The effect was very strong and remained almost constant throughout the entire period.
The research group was supported in their study by the Federal Ministry for Education and Research (BMBF), the German Research Foundation and with funding from the European Regional Development Fund (ERDF).
Where is solar energy used the most?
Solar energy is considered one of the environmentally friendly materials because it does not produce air pollutants. No greenhouse gases are released. Seasonal, day-dependent and weather-related fluctuations in the amount of energy are unfavorable. Photovoltaic cells without direct sunlight are less effective. So the researchers made a real breakthrough.
Solar energy is used to generate electricity and heat the building. Solar energy can be used for heating and feeding into the power grid. On average, individual solar cells generate a voltage of 0.5V – 0.6V In order to increase this voltage, the cells in the solar module are connected in series.
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