Prof. SONG Yanlin and Prof. WANG Yang’s group at the Institute of Chemistry, Chinese Academy of Sciences, and Prof. ZHOU Huanping from Peking university, has developed a method to improve the performance and stability of perovskite solar cells (PSCs)---novel surface diffusion engineering technique. This method could fabricate phase-pure 2D perovskite passivation layers with precisely controlled structure at the interface between the light-absorbing layer and the charge transport layer.

Perovskite solar cells (PSCs) have attracted global attention for their high-power conversion efficiency and low fabrication cost. A promising approach to enhance PSCs’ performance including combining 3D perovskites with 2D perovskite layers, which can help stabilize the interface. However, conventional liquid-based methods often produce disordered 2D layers with mixed compositions, leading to inefficient charge extraction and limited device stability.

To tackle this issue, the team introduced a solvent-free, solid-state reaction strategy called the Noninvasive Surface Reaction (NSR) strategy, which differs from conventional solution-based methods. Addressing the challenge of mixed-dimensional (n = 1, 2, 3, etc.) formation. Resulting a pure-phase 2D perovskite contact layer with a well-defined dimensionality on top of the 3D perovskite.

This approach proved highly reproducible and scalable—researchers successfully fabricated high-quality perovskite films as large as 10 cm × 10 cm. They also tested seven types of organic cations(including HABr, BABr, PEAI, OAI, HAI, BAI, and 4-MeO-PEAI) to construct phase-pure 2D perovskite contact interfaces, demonstrating the broad applicability of the method.

Furthermore, the solar cells fabricated using this technique achieved a remarkable power conversion efficiency of 26.13% (certified 25.66%), and retained full performance after 1,200 hours of continuous operation. A larger mini-module also reached 23.03% efficiency (certified 22.32%) and showed excellent operational durability.

“Our noninvasive surface reaction (NSR) strategy provides a robust, universal pathway for constructing well-defined 2D perovskite contact layers through solid-state diffusion, paving the way for more efficient and stable perovskite optoelectronics,” said Prof. SONG Yanlin.

This study was published in Nature Synthesis.

Phase-Pure 2D perovskite passivation via solid-state reaction (Image by ZHANG Kun)

Contact:

Prof. SONG Yanlin; Prof. WANG Yang

Institute of Chemistry, Chinese Academy of Sciences

Prof. ZHOU Huanping

Peking University

Email: ylsong@iccas.ac.cn; wangyang@iccas.ac.cn; hpzhou@pku.edu.cn