With energy-related CO2 emissions peaking in 2021, the need for clean energy is more pressing than ever. One such alternative to fossil fuels is solar energy. Solar cells have been developed with a variety of materials, but selenium (Se) is a desirable option because it is cheap, stable and non-toxic, said Zhao Chen of the Wuhan National Laboratory of Optoelectronics (WNLO) and the school. electronics. Information from Huazhong University of Science and Technology, China.
However, its effectiveness is limited by its low melting point and wide bandgap, which is the range in which an electronic state cannot exist. Now Chen and other researchers have overcome these limitations by mixing selenium with tellurium (Ti), making selenium solar cells a more attractive option.
The researchers published their findings in the journal Frontiers of Optoelectronics .
According to the researchers, the optimal band gap for solar cells is 1 to 1.5 eV, but the band gap for Se is about 1.8 eV, which is wider than ideal for use in solar cells. . The researchers were able to tune the solar cells to the Shockley-Quisser limit, the theoretical maximum efficiency of a single-junction solar cell, by combining selenium and tellurium.
"Alloying [selenium] with tellurium, which has the same crystal structure and narrow band gap, can adjust the band gap and raise the melting point, thus expanding the absorption band and improving the quality of [cell] films. selenium sunscreens]," Chen said. . The corresponding author is an associate professor at the Faculty of Optical Electronic Information, Huazhong University of Science and Technology. "Therefore, the Se1 - x Te x mixture is expected to improve the performance of solar cells."
The researchers also used zinc oxide (ZnO) as an electron transport layer in solar cell fabrication due to the favorable bandgap and light interaction at the zinc-selenium/tellurium oxide interface.
"Zinc oxide was chosen as an electron transport layer that can interact slightly with Se to improve their interface adhesion and reduce dangling bonds, thus reducing surface defects," Chen said.
One of the new parts of this research was this use of zinc oxide, Chen said, along with the researchers' analysis of some aspects of solar tellurium-selenium.
"The recombination mechanism and defect type of the charged solar cell Se 1 - x Te x were investigated using current- and voltage-dependent light intensity and temperature-dependent acceptance characteristics, making Se 1 - x Te x be more to help improve the alloy system." Chen said.
After producing new selenium-tellurium solar cells with zinc oxide electron transport layers, the researchers discovered that the new material retains previously known positive properties while improving efficiency by having a high absorption coefficient and a high light conductivity.
"The efficiency of ZnO/Se 0.7 Te 0.3 solar cells doubled after nine months in the air," Chen said. "ZnO/Se 0.7 Te 0.3 has been shown to have superior coupling with energy band matching and strong adhesion, with efficiencies of 1.85% previously achieved."
Researchers are trying to improve solar cell manufacturing and then expand the technology.
“The next step will be to produce high-quality Se 1 - x Te x alloy films by using holes, gap defects, etc. remove and improve device structure by adding hole transfer layer, etc., to further improve performance. 1 - Cell Te x Alloy Sunshade and reach mass production."
Provided by Higher Education Publishing
Cita : Researchers work to improve efficiency of low-cost solar cells (Sep 27, 2022) Retrieved Oct 9, 2022 at https://techxplore.com/news/2022-09-efficiency-low-cost -solar-cells.html.
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