USTC team enhances air-processed perovskite solar cells with new stabilizer

Researchers at the University of Science and Technology of China (USTC), led by Prof. XU Jixian, have developed a novel stabilizer, dimethylammonium formate (DMAFo), for air-processed p-i-n perovskite solar cells. This innovation significantly inhibits the oxidation of iodide ions and the deprotonation of organic cations, as detailed in their recent publication in Nature Energy.

The power conversion efficiency (PCE) of metal halide perovskite solar cells has seen rapid advances, surpassing 26.1% in controlled environments. However, manufacturing these cells in ambient air has been challenging due to significant efficiency and stability losses, which impede mass production and broader application.

The new stabilizer addresses the "whole-process" degradation observed when perovskite films are exposed to moisture, oxygen, and heat during air processing. DMAFo's ability to reduce halide oxidation and support hydrogen bonding with the perovskite precursor allows for the long-term stability of perovskite solutions under ambient conditions.

Further enhancements are noted during the crystallization stage in air, where DMAFo improves the crystallinity of perovskite films, thus minimizing the energetic disorder and non-radiative recombination caused by atomic defects. This development is critical as it overcomes the limitations of conventional surface passivation, which alone has proven inadequate for maintaining the integrity of air-processed cells.

As a result of these improvements, the team has achieved a maximum PCE of 25.4% and a certified stabilized efficiency of 24.7% with their 1.53-eV p-i-n perovskite solar cells processed in ambient air-performances nearly matching those of the highest-grade cells produced in nitrogen atmospheres. The successful application of DMAFo in wide bandgap perovskites also demonstrates potential for the production of stacked devices in non-inert conditions.