HIGHLY STABLE PEROVSKITE FILM WITH IONIC LIQUID ADDITIVES FOR AMBIENT AIR DEPOSITION

Abstract

Perovskite solar cells (PSCs) technology has emerged as a highly promising photovoltaic (PV) option due to remarkable advancements in power conversion efficiency (PCE). Nevertheless, the stability of PSCs continues to pose a challenge for commercialization, as factors such as moisture, oxygen, light, and temperature can lead to degradation during fabrication and actual use stage. The stability of the perovskite film is crucial for extending the device’s lifetime and performance. This research seeks to explore the degradation mechanism and improve the perovskite film’s stability by incorporating 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) and 1,3-dimethyl-3-imidazolium hexafluorophosphate (DMIMPF6) ionic liquids into a perovskite precursor using the two-step deposition technique in ambient air. The perovskite film’s degradation and PSCs’ stability were evaluated under high relative humidity conditions, averaging 73%RH without encapsulation. UV-visible spectroscopy results indicate that the most stable perovskite film, containing the BMIMBF4 ionic liquid additive, maintains its α phase perovskite structure for 144 hours without alterations in absorbance and persisted for over 336 hours before degrading into an undesirable δ phase perovskite. Furthermore, PSCs retained 74.1% of their initial PCE after 28 days of exposure to ambient conditions. This research offers promising findings for the large-scale fabrication of stable PSCs.