Scientists improve stability and scalability of low-cost solar modules, according to a report published on January 22, 2018.
This study was conducted by the scientists at the Okinawa Institute of Science and Technology Graduate University (OIST). Their innovation has resolved a fundamental weakness observed in perovskite solar cells or PSCs, which is expected to result in commercialization of PSCs.
Although PSCs are of low cost and high efficiency, and exhibit promising performance in lab tests, low stability of these cells are a disadvantage. As per the study published online in Advanced Functional Materials on December 13, 2018, titanium dioxide used in PSCs results in degradation of the device and limits their lifetime. In this study, the material was replaced with tin dioxide, a stronger conductor without these degrading properties. They optimized their method of applying tin dioxide to produce stable, efficient, and scalable PSCs.
From the experiments, it was found that tin dioxide-based devices showed lifetimes over three times longer than PSC devices using titanium dioxide. PSCs consist of layered materials, each with a specific function. The active layer, which is made from perovskite materials absorbs incoming sunlight in the form of particles called photons. When a photon strikes a solar cell, it generates negatively-charged electrons and positively-charged holes in the active layer. Scientists control the flow of these electrons and holes by sandwiching the active layer between two transport materials, thus creating a built-in electrical field.
PSCs also have an electron transport layer that helps to guide electrons in the right direction. Most PSCs employ titanium dioxide as their electron transport layer, but when exposed to sunlight, the material reacts with perovskite and ultimately degrades the device. Tin dioxide stands as a viable replacement for titanium dioxide. Researchers used a technique known as sputtering deposition to create an effective electron transport layer from tin dioxide. The new solar cells were 20 percent more efficient. Dr. Longbin Qiu, first author of the paper said, â€œWe want to scale these devices up to a large size, and though their efficiency is already reasonable, we want to push it further. We are optimistic that in the next few years, this technology will be viable for commercialization.â€
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