If a photovoltaic material is made in the form of paint that can be applied to any surface, such as the exterior of a building or a car, it will be possible to achieve energy self-sufficiency and provide low-cost eco-friendly energy to those suffering from energy poverty. Not only that, it will be easy to utilize space for installation of photovoltaics even on urban buildings and, ideally, the photovoltaic panels will be maintained by re-applying the “paint.”
South Korean researchers took a step toward reaching this goal by successfully developing high efficiency organic solution processable solar cells in the form of paint for large surfaces. This achievement was made possible by controlling the speed at which the solar cell solution solidified.
Size does matter
So far, solution processable solar cells, which work by coating the surface with the solar cell solution, still remain on a laboratory scale.
In order to give it a practical use, meaning to be used in every-day-life, it must be applied at a large area. This way, it could produce sufficient electric power. But there are material and process-related limitations, and this has been an obstacle to commercialization.
The team led by Dr. Hae Jung Son from the Photo-electronic Hybrids Research Center of the Korea Institute of Science and Technology (KIST) announced that they have identified the difference in the mechanism of film formation between a small area and a large area of organic solar cells in a solution process and, by resolving the issue concerning the related process technology, developed a high-efficiency large-area organic photovoltaics.
Researchers at KIST implemented spin-coating to the large-surface organic photovoltaic cells.
Low-cost spin-coating applies a uniform coat on a solid surface using centrifuge force and a liquid-steam interface. It is used in organic PV research during the formation of sheets to accelerate the solvent’s evaporation.
According to the researchers, spin-coating enables for massive heterojunction sheets that work better and are more replicable than the sheets produced without the process. “Commercially available organic materials become easily crystallized, which makes them unsuitable for large-area solution processes,” the team explained.
Based on this information, KIST researchers developed high-performance large-area organic photovoltaics by controlling the solvent evaporation rate following the coating step in a large-area solution process. As a result, high-efficiency large-area organic photovoltaics with 30% higher power conversion efficiency than existing photovoltaics were attained.
This research opens a new route toward a promising low-cost future for clean energies. This easy-to-use technology could be implemented in cities and remote locations, in industrialized countries and the poorest nations. Photovoltaic power is nearing a moment when its application through paint will be possible.
“The core design principles of solar cell materials capable of high-quality large-area using the solution will accelerate the development of solution processable solar cells in the future,” said Dr. Hae Jung Son.
This study “has contributed to not only raising the efficiency of next-generation solution processable solar cells but also the development of core technology for manufacturing large-area solar cell materials required for commercialization,” he added.
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