GIST Professor Kwanghee Lee has led a research team
to develop a simpler method to print tandem organic solar cells
Figure: Photograph of the tandem solar cells fabricated by nanocomposite printing process.
From left: Professor Kwanghee Lee, Research Professor Hongkyu Kang, and Ph.D. Candidate Seok Kim
Solution process organic solar cells have emerged as a promising alternative to fossil fuels for producing clean, renewable energy. Unfortunately, the wide spread use of organic solar cells have been limited by low power conversion efficiencies (PCEs). To improve the PCE of organic solar cells, a tandem approach has been developed by using two solar sub-cells that are positioned one atop the other to more efficiently utilize a broader spectrum of solar energy. However, widespread adoption of this approach has been limited by the inherent complexity of constructing the multilayer tandem design, which usually requires six or more component layers.
To improve these limitations affecting organic solar cells, a research team at the Gwangju Institute of Science and Technology (GIST) led by Professor Kwanghee Lee of the School of Materials Science and Engineering has developed a novel strategy to simplify the tandem architecture to four component layers while producing a PCE of 9.1%, which is quite remarkable in itself considering that recent advances have only just recently allowed organic solar cells to achieve PCEs of more than 10%.
The GIST researchers achieved these results by pioneering a new concept of vertical self-assembly during the printing process that takes advantage of thermodynamic forces created by the difference in surface energies of the various nanocomposite materials used in the solution processing to create the tandem organic solar cell.
As Professor Kwanghee Lee noted, "We believe that our approach will help to realize printed tandem organic photovoltaics for commercial applications and provide a universal solution to reduce the fabrication steps of various organic electronic devices."