A multifunctional ionic liquid additive for enhancing PEDOT:PSS electrode conductivity and radiative recombination efficiency in air-processed perovskite light-emitting electrochemical cells

EMIM TFSI and ethylene glycol reconstruct conductive PEDOT:PSS networks. • EMIM TFSI regulates perovskite wetting and crystallization to suppress defects. • Layer-specific regulation enables high-luminance air-processed PeLECs. Air-processed perovskite light-emitting electrochemical cells (PeLECs) are attractive for solution-processed light emission because of their simple device architecture and mobile-ion-assisted charge injection. However, their performance is still limited by resistive electrode-side charge transport, nonuniform perovskite film formation, and defect-assisted nonradiative recombination under ambient fabrication conditions. Here, we introduce 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIM TFSI) as a multifunctional ionic liquid additive to address losses in both the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) electrode and the perovskite emissive layer. The asymmetric EMIM + /TFSI − ion pair provides distinct ionic and interfacial interactions, enabling layer-dependent regulation of charge transport, film formation, and surface defect environments. In the PEDOT:PSS electrode, ethylene glycol (EG)-assisted EMIM TFSI treatment promotes PEDOT-rich domain enrichment and improves the interconnection of conductive pathways, increasing the conductivity to 4676 S cm −1 while maintaining a visible transmittance of 85.9%. In the perovskite emissive layer, EMIM TFSI improves precursor wetting and regulates nucleation/crystallization processes, leading to smoother, more compact, and more crystalline films. Meanwhile, EMIM TFSI-associated surface regulation modifies the Pb/Br-related local chemical environment, reduces energetic disorder, and suppresses defect-assisted nonradiative recombination, increasing the photoluminescence quantum yield from 54.6% to 66.7%. As a result, the dual-modified air-processed PeLEC achieves a maximum luminance of 3382.6 cd m −2 and a maximum external quantum efficiency of 5.83%. This work demonstrates a multifunctional ionic liquid regulation strategy for coupling electrode conductivity, emissive-layer quality, and electroluminescence output in structurally simplified air-processed PeLECs.