New Giant Acceptors Propel Organic Solar Cells to 20.02% Efficiency

A research team led by Prof. Ge Ziyi from the Ningbo Institute of Materials Technology and Engineering (NIMTE) has achieved a significant milestone in solar energy technology. They developed innovative giant acceptors that enable organic solar cells (OSCs) to reach a power conversion efficiency (PCE) of up to 20.02%. This advancement marks a critical step towards enhancing the viability of OSCs in commercial photovoltaic applications.

Breakthrough in Organic Solar Cell Technology

Organic solar cells are known for their lightweight, mechanical flexibility, and cost-effective manufacturing processes, making them prime candidates for next-generation solar technology. Traditionally, high-performance OSCs have relied on halogenated solvents, which, despite their efficiency, present challenges in mass production due to their high volatility. In contrast, this new research explores high-boiling-point nonhalogenated solvents, such as toluene, which are more suitable for scaling up production but often lead to reduced efficiency.

To counter this issue, the research team introduced two giant guest acceptors—designated G-1O and G-3O—into blends of PM6:BTP-eC9. By designing these acceptors with distinct oxygenated side chains, they were able to extend the crystallization time of the blend. This approach effectively suppressed excessive aggregation and enhanced phase separation, which are crucial for optimizing the performance of OSCs.

Performance Enhancements and Scalability

The study, published in Advanced Materials, highlights how the incorporation of G-1O, featuring a shorter oxygenated side chain, achieved better molecular planarity compared to G-3O. This improvement facilitated a more uniform phase distribution, which is vital for efficient charge transfer and minimizing voltage loss. As a result, the ternary device utilizing G-1O achieved a PCE of 19.90%, surpassing the 17.90% efficiency of the G-3O-based device.

To further enhance the performance of the G-1O-based device, the team applied a 100 nm anti-reflection coating (ARC) layer, which elevated its PCE to the impressive 20.02%. In addition to these achievements, the researchers fabricated a large-area module measuring 15.6 cm² using the PM6:BTP-eC9:G-1O system. This module demonstrated a high PCE of 16.97% and notably contained no dead zones, confirming the technology’s scalability and environmental advantages.

This work not only establishes a viable pathway for the development of high-performance OSCs using nonhalogenated solvents but also underscores their potential role in the future of sustainable energy solutions. The findings are a promising step forward in making organic solar cells a competitive option in the global market for photovoltaic technologies.