New coating makes perovskite LEDs stable in air for the first time
Researchers have solved a stubborn problem holding back perovskite light-emitting diodes: a chemical residue that degrades performance. A simple thiol-based coating removes the unwanted material while protecting the device, enabling displays to survive 15 days without protective encapsulation. This breakthrough could slash manufacturing costs for next-generation displays and accelerate commercialization of perovskite LED technology.
Originaltitel: Mitigating Residual FAI for Air-Stable FAPbI3 LEDs
Formamidinium lead iodide ( FAPbI 3 ) perovskite light-emitting diodes (PeLEDs) showing record external quantum efficiencies (EQEs) are typically fabricated in a n-i-p structure through the deposition of a precursor solution rich in FAI on top of ZnO/ITO substrates. The ZnO electron transport layer is known to interact with the precursor solution during the fabrication, which can help to remove most of the excess FAI to ensure good stoichiometry and crystallinity as well as promote the formation of films with strong emission. However, residual FAI often remains on the perovskite surface, where it compromises device efficiency and stability. In this study, we introduce a thiol-functionalized tertiary ammonium halide, 2-diethylaminoethanethiol hydrochloride (DEAET). Beyond acting as a passivation agent via synergistic hydrogen bonding and electrostatic interactions, DEAET effectively facilitates the regulation of excess formamidinium iodide (FAI). This dual functionality suppresses non-radiative pathways and promotes radiative recombination. The resulting DEAET-passivated LEDs exhibit increased EQE and an impressive 15-days air stability without encapsulation. The encouraging findings of this study lay the foundation for the utilization of thiol-based salts as efficient agents for interface engineering in FAPbI 3 perovskite, that opens new possibilities for air-stable perovskite light-emitting diodes.