Researchers out of the University of Kansas have uncovered key data on how certain organic semiconductors in solar panels are able to perform at record-breaking efficiencies.
Many of today's solar panels are made with silicon, a common semiconductor used in electronics, as SciTechDaily reported. But these are costly and rigid, making them difficult to install on curved surfaces.
However, researchers have also been experimenting with organic semiconductors, which are more "Earth-abundant," cheaper, and more environmentally friendly to use, per the report.
"They can potentially lower the production cost for solar panels because these materials can be coated on arbitrary surfaces using solution-based methods — just like how we paint a wall," Wai-Lun Chan, associate professor of physics and astronomy at the university, shared, per SciTechDaily.
"These organic materials can be tuned to absorb light at selected wavelengths, which can be used to create transparent solar panels or panels with different colors. These characteristics make organic solar panels particularly suitable for use in next-generation green and sustainable buildings," he continued.
Some of these applications are already underway, including stretchable versions that could one day be printed on clothing and transparent solar coatings for windows, which could potentially support 25% of a building's energy load through renewables.
So far, the ability to install the new types of solar-collecting panels or coatings in more places seems to be limited by the low light-to-energy conversion rates, which stand around 12% compared to 25% for silicon versions, as SciTechDaily noted.
However, more recent developments using organic non-fullerene acceptors (NFA) in panel constructions have led to much higher conversion efficiencies, with some reaching closer to 20%, per the news outlet.
Chan and his team of graduate students recently published a breakthrough study exploring the topic, SciTechDaily reported. According to the article, lead author Kushal Rijal used a technique they called "time-resolved two photon photoemission spectroscopy" to measure the phenomenon and found that a microscopic mechanism plays a large role in the NFA's outstanding performance.
"In these measurements, Kushal [Rijal] observed that some of the optically excited electrons in the NFA can gain energy from the environment instead of losing energy to the environment," according to Chan.
"This observation is counterintuitive because excited electrons typically lose their energy to the environment like a cup of hot coffee losing its heat to the surroundings."
According to SciTechDaily, Rijal elaborated, "For organic molecules arranged in a specific nanoscale structure, the typical direction of the heat flow is reversed for the total entropy to increase. This reversed heat flow allows neutral excitons to gain heat from the environment and dissociates into a pair of positive and negative charges. These free charges can in turn produce electrical current."
This insightful discovery could help people develop even more efficient and flexible solar cells to keep pace with the ever-growing gains in renewable energy generation.
The report also shared that these findings could be used for more efficient processes in converting carbon dioxide in organic fuels. This would provide yet another solution to reducing our reliance on dirty fuels, while also reducing planet-warming pollution from the atmosphere.
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