Ion-pair pinning on perovskite quantum dots for high-efficiency air-processed light-emitting diodes with Rec. 2020...

Perovskite quantum dot light-emitting diodes (QLEDs) offer superior efficiency and high colour purity, making them promising candidates for next-generation lighting and display technologies. However, fabricating the emissive perovskite quantum dot (QD) layer typically requires a protective atmosphere due to its air sensitivity, thereby increasing production costs and limiting industrial scalability. Here, we propose an ion-pair pinning strategy by using tetraalkylammonium triflate (NR₄OTf) to enable ambient-air processing of formamidinium lead bromide (FAPbBr₃) QD films. The trifluoromethanesulfonic acid anions (OTf^-) hydrogen bond with FA⁺, inhibiting its detachment and passivating the uncoordinated Pb²⁺, while the tetraalkylammonium cations (NR₄⁺) serve as X-type ligands to inhibit deprotonation. This dual ion-pair pinning effect stabilises the QD lattice and provides surface resistance to moisture and oxygen, thereby improving the uniformity, stability, and optoelectronic performance of air-processed QD films. The as-constructed air-processed QLED achieves a high external quantum efficiency (EQE) of 21.3% and a peak luminance of over 3 × 10⁴cd m^-2 at 529 nm with Rec. 2020 compliance (EQE of 23.9% and luminance of over 8 × 10⁴cd m^-2 for the N₂-processed QLED). Our work eliminates the reliance on inert gas protection in perovskite QLED fabrication, laying a foundation for their low-cost, large-scale manufacturing and expansion into diversified applications.