New efficiency record set for eco-friendly nanocrystal solar cells

New efficiency record set for eco-friendly nanocrystal solar cells

by Erica Marchand

Paris, France (SPX) Oct 25, 2024

As climate change accelerates the shift towards renewable energy sources, solar cells are becoming increasingly vital. Solar power generation in Spain, for instance, grew by 28% in 2023 compared to the previous year, contributing to 20.3% of the country’s total energy mix. However, despite their widespread adoption, solar cells still rely on materials that are not always environmentally sustainable. Expanding solar technology to a broader range of applications, such as powering buildings, infrastructure, and vehicles, requires the development of flexible, lightweight, and cost-effective solar cells.

Colloidal silver bismuth sulfide (AgBiS2) nanocrystals have recently emerged as a promising eco-friendly material for ultra-thin solar cells. These nanocrystals possess an exceptionally high absorption coefficient, but current manufacturing techniques for such solar cells rely on multi-step processes that are costly and inefficient. A new single-step approach using nanocrystal inks could streamline production, but defects on the nanocrystal surfaces have limited efficiency.

To address this issue, researchers at the Institute of Photonic Sciences (ICFO), led by ICREA Prof. Gerasimos Konstantatos, have developed an innovative post-deposition in situ passivation (P-DIP) technique. This method enhances surface passivation, leading to nanocrystal ink films with superior optoelectronic properties. Their work, published in “Energy and Environmental Science”, achieved a power conversion efficiency of around 10%, surpassing the performance of previous AgBiS2-based solar cells.

Dr. Jae Taek Oh, the study’s first author, explained the importance of surface passivation: “Imagine a bumpy road that slows down cars. Surface passivation is like repaving the road, making it smoother so cars can move without getting stuck. In our case, the removal of surface defects is very important to facilitate the transportation of charge carriers created from light absorption in nanocrystal films.”

The research team’s P-DIP strategy improved the quality of the nanocrystal films by addressing surface defects, leading to a significant boost in efficiency. By using a multifunctional molecular agent containing chlorine, they were able to stabilize the nanocrystals and ensure even dispersion in the solution, which resulted in smooth film coatings and enhanced carrier transport.

This combination of techniques has set a new performance record for sustainable, eco-friendly solar cells.

Research Report:Post-deposition in situ passivation of AgBiS2 nanocrystal inks for high-efficiency ultra-thin solar cells