An Universal Multi-Additive Strategy to Enhance Efficiency and Stability in Inverted Perovskite Solar Cells

Abstract

Perovskite solar technology has become a trend topic in the last decade, reaching promising efficiencies up to 25.7%. Researchers mainly focused on obtaining high performances rather than caring for stability under accelerated stress condition, such as thermal and light soaking tests. For this reason, we studied a standard triple cation perovskite (~1.58eV) and wider bandgap perovskite (~1.63eV) with the scope of finding a common strategy to build a robust device stable over time independently of the perovskite used. We use a combination of additives inside the perovskite ink: ionic liquids 1-Butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF4), alkylamine ligands oleylamine (OAm) and benzylhydrazine hydrochloride (BHC). Our work reveals that the combination of these additives helps to improve efficiency and stability of the entire device, reaching a power conversion efficiency of over 20% on both types of perovskite and stability beyond 1000 hours under continuous light-soaking. The universal applicability of this method further applied to a more robust methylammonium free perovskite leading to an impressive stability both under light soaking and under 85°C, showing T 90 > 1500 hours and T 80 > 8658 hours, respectively.

Keywords: perovskite solar cells, additive engineering, solar cell stability, ISOS protocols