Korean research institute claims 12.2% efficiency world record for flexible CTZS solar cell


Scientists at South Korea’s Daegu Gyeongbuk Institute of Science and Technology (DGIST) have achieved a power conversion efficiency of 12.2% for a copper zinc tin sulfide (CZTS) solar cell built on a flexible substrate and with a size of over 1cm².

The result, which the researchers said is a world record for the CZTS PV technology, improves the cell's previous record efficiency of 11.4%, which they achieved in November 2019. In 2013, Japanese manufacturer Solar Frontier had obtained a 12.6% efficiency but this was obtained on a cell measuring just 0.4cm².

The Korean group said the cell was improved by utilizing a heteroatom doping optimization technology, without providing further details. In its previous announcements, it has said the cell is based on a novel, seven-layer thin film structure which they found offered superior performance to a more standard three-layer film in terms of efficiency and large area uniformity.

“Our research achievement has presented ways to secure the uniformity of large-area process, which can cause issues in commercialization,” said the paper’s lead author, Kee-Jeong Yang, at the time. “We will be able to advance the commercialization of [a] next-generation solar cell which is applicable in various fields, such as building outer walls.”

In its latest announcement, in which the efficiency world record was disclosed, the DGIST said it had signed a memorandum of understanding with Korean manufacturer SolarFlex Ltd to start commercial production of the solar cells. “The cooperation not only includes the collaboration for the commercialization of the thin-film solar cell technology, but also the joint research related to the development of original technologies, such as tandem technology, for achieving further high efficiency of the solar cells,” the research institute added.

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SolarFlex currently operates a 10 MW factory in South Korea.

Solar cells based on copper zinc tin sulfide (CZTS) have attracted plenty of attention in recent years thanks to their reliance on cheap, abundant, non-toxic materials and their resulting potential for low-cost production.

Thus far the efficiencies achieved with various combinations of such materials have lagged well behind the achievements of silicon and other technologies, with leading research groups struggling to surpass the 10% mark, even on smaller laboratory devices.

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