UNIST Improves Organic Solar Cells by Lowering Toxicity and Increasing Efficiency

Uniform Film Formation Achieved Even on 200cm² Area... High Efficiency Surpasses 11.44%

Eco-friendly Non-halogen Solvent and Slot-die Coating Technology Signal Commercialization Prospects

A large-area organic solar cell of 200 ㎠, fabricated using a low-toxicity non-halogenated solvent, achieved a power conversion efficiency (PCE) of 11.44%.

This is expected to serve as a significant turning point, bringing the commercialization of organic solar cells one step closer.

A joint research team led by Professor Kim Bongsoo of the Department of Chemistry at UNIST (President Park Jongrae), Principal Researcher Kang Hongkyu of the Next-Generation Energy Research Institute at GIST (President Lim Gicheol), and Professor Lee Kwanghee of the School of Materials Science and Engineering, dramatically improved the uniformity of the photoactive layer film by asymmetrically extending the alkyl chains of the non-fullerene acceptor. As a result, they succeeded in realizing a high-efficiency, large-area organic solar cell.

Research team. (From bottom left: Bomi Kim, Bongsoo Kim, Duhyun Eom)

Conventional large-area organic solar cells have faced major obstacles to commercialization due to the use of highly toxic halogenated solvents such as chlorobenzene. However, when using relatively less toxic non-halogenated solvents, the aggregation phenomenon of non-fullerene acceptors within the photoactive layer led to reduced film uniformity and, consequently, decreased efficiency of large-area organic solar cells.

To address this issue, the joint research team adopted a method of asymmetrically extending the alkyl chains of the non-fullerene acceptor. As the solubility of the non-fullerene acceptor improved in non-halogenated solvents, aggregation was effectively suppressed, enabling the formation of a uniform photoactive layer film even over a large area of 200 ㎠.

In particular, the photoactive layer of the 200 ㎠ organic solar cell based on PM6:L8-BO(HU-DT):PC70BM exhibited the least aggregation and the highest miscibility between materials, achieving a record-high efficiency of 11.44%.

Furthermore, the slot-die coating method used in the process is suitable for mass production through roll-to-roll processing, further enhancing the commercialization potential of next-generation organic solar cells.

Photo of a large-area organic solar cell with an active layer area of 200 cm².

Professor Kim Bongsoo stated, "We succeeded in suppressing aggregation within the photoactive layer by asymmetrically extending the alkyl chains of the non-fullerene acceptor," adding, "This will make a significant contribution to the development of materials for the commercialization of organic solar cells."

This research was supported by the National Research Foundation of Korea, with Kim Bomi and Eom Dohyun of UNIST and Lee Yangsu of GIST participating as co-first authors. The results were published online in the world-renowned journal 'Advanced Functional Materials' on July 18.

This content was produced with the assistance of AI translation services.