Development of large-area, high-performance organic solar cells using water to control the morphology of the active layer thin film

Gwangju, Korea, September 16, 2022 /PRNewswire/ — Organic solar cells (OSCs), which use organic polymers to convert sunlight into electricity, have received a great deal of attention in recent years due to their desirable properties for next-generation energy sources. These include light weight, flexibility, scalability, and high power conversion efficiency (>19%). Several strategies currently exist to enhance the performance and stability of OSC. However, the problem remains that it is difficult to control the morphology of the active layer of OSCs when scaling up to large areas. This makes it difficult to obtain high-quality active layer thin films and fine-tune device efficiency.

In a recent study, a team of researchers from the Gwangju Institute of Science and Technology in South Korea began to tackle this issue. in their work, Advanced functional materials, they proposed a seemingly counterintuitive solution: using water treatment to control the morphology of the active layer. “Water is known to interfere with the performance of organic electronic devices as it remains in the ‘trapped state’ of organic materials, impeding charge flow and degrading device performance. However, by using water as the medium of the treatment method, rather than organic solvent-based active solutions, we thought we could achieve the necessary physical changes without chemical reactions.‘ explains Professor Kim Dong-yu, who led the study.

The researchers chose the polymers PTB7-Th and PM6 as the donor material and PC.₆₁BM and EH-IDTBR and Y6 As an acceptor material in the active layer. They realized that inducing a vortex to mix the donor and acceptor materials in the active solution could lead to a well-mixed active solution, but it was not sufficient. was hydrophobic, the researchers decided to use deionized (DI) water and vortex to stir the solution. The donor and acceptor materials were left in chlorobenzene (host active solution) overnight, DI water was added to the solution and it was stirred and vortexed. Due to the hydrophobicity of the solution, water pushes on the donor and acceptor molecules, causing them to dissolve more finely into the solution. The solution was then allowed to rest and the water separated from the solution. This water was then removed and the water-treated active solution was used to prepare thin films of PTB7-Th:PC.₆₁BM (F, fullerene), PTB7-Th: EH-IDTBR (NF, fullerene), PM6: Y6 (H-NF, highly efficient non-fullerene).

The researchers then investigated the photovoltaic performance of these thin films in a slot-die coated reverse OSC configuration and compared it with that of OSCs without water treatment.

“It was observed that the water-treated active solution resulted in a more uniform active layer thin film that exhibited higher power conversion efficiency compared to the non-water-treated one.In addition, we fabricated a large-area OSC module with an active area of ​​10 cm²showed a high conversion efficiency of 11.92% in the water-treated H-NF filmemphasizes Professor Kim.

Overall, this study provides guidelines for developing large-scale and efficient OSCs using a very simple, economical and environmentally friendly method, opening the door to OSC realization and commercialization. can do.

reference

DOIs: https://doi.org/10.1002/adfm.202204871

Original article title: Introduction of Water Treatment to Slot Die Coated Organic Solar Cells to Improve Device Performance and Stability

journal: Advanced functional materials

*Corresponding author email: [email protected]

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SOURCE Gwangju Institute of Science and Technology