As the area of perovskite films and devices increases, their performance tends to deteriorate - which researchers from the Chinese Academy of Science (CAS), University of Science and Technology of China and Dalian University of Technology explain can be linked to defects that accumulate at the bottom surface without proper passivation. In an attempt to address this issue, the team introduced a unique molecule (1-(4-Fluorophenyl)−2-pyrrolidone, or FPP) as an additive in large-area blade-coating perovskite films.
During the top-down crystallization process, the FPP molecule forms an intermediate phase with the perovskite components and subsequently self-deposits at the bottom surface. Consequently, the crystallization kinetics of the large-area thin films are regulated, and the bottom surface is effectively and uniformly passivated in one single-step processing.
The team fabricated large-area perovskite films using the blade-coating method and introduced FPP to improve perovskite film quality. The FPP self-deposited downward and finally gathered at the perovskite film bottom, passivating the defects in the bottom surface. Consequently, grains grow sufficiently in various positions across the large-area thin film, enabling a more controllable and homogeneous crystallization process, ultimately forming uniform large-area perovskite films. As a result, the phenomenon of efficiency decline caused by device area amplification is suppressed. This strategy achieved a PCE of 23.41% for single-junction devices and 20.75% for solar modules with excellent stability, which provides a simple and effective method for scalable perovskite solar cells.
This novel self-passivation technique is tailored for large-area perovskite solar cells to mitigate the efficiency decline. It is compatible with commercial manufacturing and can allow for scaling up solar cell area and holding high efficiency.
