A team led by Prof. Do Hyun RYU (Dept. of Chemistry) successfully synthesized new indoline dyes which are pure organic materials, and by applying those to the thin film dye-sensitized solar cells with the thickness of the photoactive layer is 2 micrometers (μm), they achieved the world’s highest solar energy conversion efficiency of 9.1% .

Dye-sensitized solar cells with transparency, flexibility, various colors, and indoors application capability have received many researchers’ attention, because it can be used for many applications including Building integrated photovoltaic systems (BIPV).

The development of thin film dye-sensitized solar cells with high efficiency is recognized as very important. However, organic dyes which had been previously developed only showed high energy conversion efficiency at thick films of over 10 micrometers (μm), while having low efficiency with thin films.

Through this research, the team designed and synthesized new indoline-based dyes which possess a plenary structure. They were also able to identify the correlation between the alkyl chain length and the factors involved in the efficiency of organic dyes, and found that the power conversion efficiency is dependent on the thickness of the layer.

"The significance of this study is a development of new organic dye-sensitized solar cells with high efficiency at thin films. The research also presents a direction to the design of a new organic dye structure by identifying how the length of the alkyl chain attached to an organic dye which has a plane structure,  affects light energy conversion efficiency", said Prof. RYU.

This study was conducted in collaboration with Prof. Tae Hyeok KWON and his team from Ulsan National Institute of Science and Technology, and published as a cover page in the Advanced Functional Materials on Oct. 10^th with the dissertation title of “Photoactive Thin Films: Indoline-Based Molecular Engineering for Optimizing the Performance of Photoactive Thin Films.”