Research Team Achieves 20.02% Efficiency in Organic Solar Cells

A research team has successfully developed organic solar cells (OSCs) that achieve a power conversion efficiency (PCE) of up to 20.02%. This milestone was made possible through the introduction of novel giant acceptors featuring an oxygenated linker. The study, published in Advanced Materials, highlights the potential of these nonhalogenated-processed OSCs for next-generation photovoltaic technology.

OSCs stand out for their lightweight design, mechanical flexibility, and low-cost fabrication. These characteristics make them appealing candidates for renewable energy solutions. Traditional OSCs, however, depend on low-boiling-point halogenated solvents to attain high efficiencies. This reliance presents a significant barrier to mass production due to the solvents’ high volatility. While alternatives like toluene and o-xylene offer a more suitable option for scaling production, they often compromise efficiency by resulting in poor morphology.

Innovative Solutions in Organic Solar Cell Production

To overcome these challenges, the team, led by Prof. Ge Ziyi from the Ningbo Institute of Materials Technology and Engineering of the Chinese Academy of Sciences, employed toluene to streamline the fabrication process. This approach is tailored for scalable production of organic photovoltaics. The researchers introduced two giant guest acceptors, known as G-1O and G-3O, into blends of PM6:BTP-eC9.

The introduction of these acceptors extended the crystallization time of the blend, which effectively suppressed excessive aggregation while enhancing phase separation. Both G-1O and G-3O maintain the advantages of Y-derivative acceptors, including precise molecular architectures and excellent photoelectric properties. This leads to an optimized active layer morphology conducive to better performance.

Performance comparisons revealed that G-1O, characterized by its shorter oxygenated side chain, improved molecular planarity. This structural enhancement enabled a more homogeneous phase distribution, promoting efficient charge transfer and reducing voltage loss. The ternary device utilizing G-1O achieved a PCE of 19.90%, significantly outperforming the G-3O-based device, which reached a PCE of 17.90%.

To further augment the performance of the G-1O-based device, the researchers applied a 100 nm anti-reflection coating (ARC) layer, resulting in the notable efficiency of 20.02%.

Scalability and Environmental Benefits

In addition to high efficiency, the researchers successfully fabricated a 15.6 cm² large-area module using the PM6:BTP-eC9:G-1O system. This module achieved a PCE of 16.97% and notably contained no dead zones, underscoring the technology’s scalability and eco-friendly processing advantages.

This groundbreaking work establishes a viable pathway for the development of high-performance OSCs utilizing nonhalogenated solvents. The findings emphasize the significant potential for commercial applications in the photovoltaic sector, paving the way for more sustainable energy solutions.