POSTECH-UNIST Develop Organic Solar Cells with Over 20% Conversion Efficiency

POSTECH, in collaboration with a UNIST (Ulsan National Institute of Science and Technology) team, has established a new theory that accurately predicts the performance limits of organic solar cells. Through this, they have developed a material that breaks through the 20% threshold for 'power conversion efficiency,' the rate at which light is converted into electricity.

The 'Shockley-Queisser (SQ) limit theory,' proposed in 1961, was created based on inorganic semiconductors with regularly arranged atoms. Since organic semiconductors have unique characteristics, such as imperfect light absorption and energy loss, this theory could not be applied directly, limiting actual material design.

Based on a refined theory that reflects the energy loss of organic semiconductors, the research team controlled the structure and molecular arrangement of 'electron acceptor' materials to realize theoretically optimal conditions in actual materials. Experimental results showed that the organic solar cells fabricated by the team recorded a power conversion efficiency exceeding 20%. Furthermore, when applied as an electrode in a solar-based hydrogen production system, the material demonstrated stable operation even in underwater environments.

This achievement establishes a new standard for the design of next-generation organic solar cells. The related findings were published in the Journal of the American Chemical Society, an international academic journal in the field of chemistry.