Improving the operational stability of perovskite solar cells

Perovskite solar cells have revolutionized the field of sustainable energy research. Hybrid perovskites have attracted a lot of interest in the field of solar energy because of their light-harvesting capacity combined with a low cost of manufacturing, making perovskite solar cells (PSCs) prime candidates for replacing current silicon-based devices. Perovskites also show great potential in a range of applications that include LED lights, lasers, and photodetectors.

However, one of the obstacles on the way to commercializing perovskite solar cells is their operational stability, which puts them at a disadvantage compared to photovoltaic technologies already on the market.

Now, scientists at École Polytechnique Fédérale de Lausanne (EPFL) have found a way to improve both power conversion efficiency and operational stability of perovskite solar cells, a crucial step towards their commercialization.

The method treats perovskite solar cells with two alkylammonium halide modulators that work synergistically to improve solar cell performance. These modulators were used as passivators, compounds used to mitigate defects in perovskites, which are otherwise promoting the aforementioned degradation pathways.

In their study, researchers were able to use the two modulators to stop halide segregation and thereby substantially reduce the drops in power-conversion efficiency seen in the long-term use of perovskite solar cells.

The new approach resulted in power-conversion efficiencies of 24.9% for one perovskite composition (α-FAPbI₃) and 21.2% for the other (FA₆₅MA₃₅Pb(I₆₅Br₃₅)₃). About 90% and 80% of the initial efficiencies were retained after 1200 and 250 hours of continuous operation, respectively.

“By addressing the critical issue of stability, our results represent an important step towards large-scale practical applications of PSCs,” the authors write.

Journal reference:

1. Essa A. Alharbi, Anurag Krishna, Nikolaos Lempesis, Mathias Dankl, Irea Mosquera Lois, Michael A. Hope, Thomas P. Baumeler, George Kakavelakis, Aditya Mishra, Felix Eickemeyer, Olivier Ouellette, Thanyarat Chawanpunyawat, Anders Hagfeldt, Shaik M. Zakeeruddin, Lyndon Emsley, Lukas Pfeifer, Ursula Rothlisberger, and Michael Grätzel. Cooperative passivation of perovskite solar cells by alkyldimethylammonium halide amphiphiles. Joule, 2022; DOI: 10.1016/j.joule.2022.11.013