A research team led by Prof. PAN Xu from the Hefei Institutes of Physical Science of the Chinese Academy of Sciences has proposed a novel strategy to improve the performance of perovskite solar cells. Their strategy involves creating a robust connection between different layers of the solar cell using a molecular bridge made of ammonium cations.

The results were published in Energy & Environmental Sciences.

Perovskite solar cells have attracted considerable attention for their remarkable power conversion efficiencies, which have exceeded 25%. However, there is still much room for improvement, particularly in terms of increasing the fill factor (FF) of these devices. FF represents a solar cell's ability to deliver maximum current under optimal conditions, and any advances in this area are highly sought after.

To overcome the limitations associated with FF, the researchers optimized the bottom interface of the solar cell. They ingeniously developed a strategy to redistribute localized electrostatic potential by using ammonium cations as molecular bridges with different degrees of substitution.

The key to this strategy is to create a strong connection between different layers of the solar cell using a molecular bridge made of ammonium cations. The researchers used ammonium cations with different degrees of substitution as a molecular bridge to create a robust interconnection between layers.

Theoretical analysis showed that the molecular bridge molecules helped to flatten the localized potential and establish efficient contacts between layers. Experimental results showed that the robust bottom interface improved the extraction and transport of photo-generated carriers, thereby enhancing the overall device performance.

The interfacial molecular bridging strategy presented in this work could potentially provide a new optimization direction for high performance perovskite solar cells and advance them toward commercialization.

By addressing the limitations associated with the FF, this study contributes to the ongoing development of high performance perovskite solar cells and their potential widespread use in clean energy generation.

Overview of the reported state-of-the-art PSCs and robust interface construction. (Image by YE Jiajiu)

Charge carrier dynamics and energetic properties. (Image by YE Jiajiu)