Aiming to explore the potential of sulfur-based additives for increasing both device power conversion efficiency and moisture stability of perovskite solar cells, researchers from BCMaterials (Spain), Huazhong University of Science and Technology (China), Max Planck Institute for Polymer Research (Germany) and CNRS (France) have reported a mechanism for the local nanoscopic humidity ingression into a multifunctional additiviated formamidinium-loaded halide perovskites.
a) The molecular structure of additives used. Image from: Advanced Energy Materials
By tuning the iodide and bromide tails of the additives, the influence of sulfur heteroatom containing ammonium-amidinium salts on the photo-physical and device properties of a formamidinium-rich perovskite absorber was uncovered.
In addition, the process of strong water adsorption was excluded through the proton-migration mechanism, thereby significantly improving the moisture resistance of perovskite films.
The high crystallinity and long lifetime decay allowed a higher PCE of 25.14% to be achieved compared to the control at 22.49%, along with improved long-term stability by retaining 99.6% of the initial PCE after 1000 h.
