Next-gen Solar Cells
A Korean research team’s development of technology to fabricate highly efficient polymer solar cells (PSCs) is expected to contribute to accelerating their commercialization.
The Ministry of Science, ICT and Future Planning (MSIP) announced on October 20 that a research team led by Song Myoung-hoon, assistant professor of the School of Mechanical and Advanced Materials Engineering at Ulsan National Institute of Science and Technology (UNIST), improved problems related to existing PSCs. The research was supported by the Mid-career Researcher Program funded by the MSIP and the National Research Foundation of Korea (NRF).
PSCs convert light energy, obtained from polymers that absorb sunlight, to electrical energy. They are receiving a lot of attention as next-generation solar cells due to the low production costs and few constraints in shape or weight. But the commercialization of PSCs has not been made possible owing to lower photovoltaic effects in comparison with solar cells made from silicon.
The research team has successfully improved the efficiency of PSCs by applying polar solvents to the electron transport layer of the ripple-structure zinc oxide (ZnO-R). With the coating of a thin film, high-energy barriers between electron transport and photoactive layers were lowered, which led to enhanced electron mobility. Test results showed that PSCs applied with polar solvents improved in efficiency by more than 30% compared with those without.
In general, solar cells need to have over 10% efficiency in the conversion of sunlight into electricity for commercialization. Song’s team developed solar cells with 8.69% efficiency. The development is especially meaningful in that commonly used materials such as ethanol and methanol were utilized as polar solvents instead of synthetic materials.
Professor Song said, “In the past, self-assembled monolayers, ionic liquids, and polyelectrolytes were used to lower energy barriers between metal oxides and an active layer. But it was a real hassle to synthesize the necessary materials, and the efficiency of the method was not much improved.” He added, “The technology developed by our team solved the cumbersome procedure, and realized high efficiency by employing widely-used polar solvents.”
This study was published online in the October 2 issue of Advanced Materials, a weekly journal in the materials sciences.