Molecular locking strategy enables efficient and scalable organic solar cells

Organic solar cells (OSCs) are devices that convert sunlight into electricity using carbon-based organic materials rather than the silicon used in conventional solar panels.

OSCs offer solution processability, mechanical flexibility, low-cost fabrication, and compatibility with large-area manufacturing. They also deliver impressive laboratory efficiencies, making them leading candidates for next-generation photovoltaics. However, forming dense, stable self-assembled monolayer (SAM) contacts on indium tin oxide (ITO) surfaces remains challenging. These contacts tend to desorb under continuous light and heat, thus limiting the commercial application of OSCs on a large scale.

Now, Prof. GE Ziyi's group from the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS) has developed a molecular locking strategy using a vacuum-deposited InCl_x interlayer to stabilize the interface between the electrode and the hole-transport layer in OSCs. The interlayer triggers ligand exchange, forming a robust, multidentate In-O-P coordination network that densely and uniformly anchors SAMs.

This approach, published in Joule on October 21, enables highly efficient, stable photovoltaic devices and offers a pathway toward scaling up organic solar technology.

Using this molecular locking interface, the small-area OSCs developed by the researchers achieved a power conversion efficiency (PCE) of 20.4%.

"We scaled the technique to large-area modules with an aperture area of 15.6 cm², reaching a record active-area PCE of 18.8%," said Prof. LIU Quan, corresponding author of the study.

The devices also demonstrated promising operational stability. After 2,000 hours of maximum power point tracking under continuous operation at 25 °C, they retained more than 85% of their initial efficiency.

This strategy provides a universal interface platform for efficient, stable, and scalable organic photovoltaic modules, showing promise for overcoming the long-standing trade-off between efficiency, stability, and scalability.

This work was supported by the National Natural Science Foundation of China and the Key Program of the Ningbo Public Welfare Research Plan.