A new method boosts efficiency of organic solar cells

A new method boosts efficiency of organic solar cells
by Simon Mansfield
Sydney, Australia (SPX) Dec 06, 2024

The integration of polymeric insulators in organic solar cells has driven major advancements in the field, addressing challenges related to molecular conformation, film crystallinity, and defect state reduction. Traditionally, these improvements were attributed to enhanced film morphology resulting from insulating materials. However, a novel discovery by Professor Hang Yin's team at Shandong University has unveiled a previously unknown mechanism driving performance gains in organic semiconductors.

The research introduces the concept of the "insulator-donor electron wavefunction coupling effect," which provides a new approach for enhancing electron mobility in donor systems. The team demonstrated that blending D-A-type donor polymers with insulating materials featuring electron-rich side chains can amplify electron mobility by as much as 100 times. This phenomenon is distinct from earlier mechanisms based on morphological optimization.

Theoretical calculations revealed that the electron-rich groups in the insulating material directly couple with the donor polymer's D unit, lowering the energy barrier for electron transport. This coupling significantly enhances intrachain electron movement, a conclusion supported by experimental data.

Leveraging this coupling effect, the researchers fabricated PM6/L8-BO pseudo-bilayer organic solar cells, achieving a record-setting power conversion efficiency (PCE) of 19.50% (certified at 19.18%). The findings offer a fresh perspective on quantum effects in polymeric insulators while proposing a straightforward and effective method for improving organic solar cell performance.

The findings were published in National Science Review under the title "Insulator-Donor Electron Wavefunction Coupling in Pseudo-Bilayer Organic Solar Cells Achieving A Certified Efficiency of 19.18%." The study's co-first authors include Jiangkai Sun (PhD, Shandong University), Xue Yang (Master's student, Shandong University), and Ruijie Ma (postdoctoral researcher, Hong Kong Polytechnic University). Professors Hang Yin, Xiaotao Hao, Kun Gao (Shandong University), and Gang Li (Hong Kong Polytechnic University) served as corresponding authors.

Research Report:Insulator-donor electron wavefunction coupling in pseudo-bilayer organic solar cells achieving a certificated efficiency of 19.18%