Meanwhile, flexible alternating current electroluminescence (ACEL) devices widely used in dynamic graphic display, bionic electronic skin, visual health monitoring equipment, and large-area display textiles have attracted people's attention. [2][3][4] Among them, the high-performance flexible electrode is one of the critical components for developing a promising flexible ACEL device, which often affects the performance of the whole equipment in various working environments. Therefore, selecting stable and high-performance electrodes is crucial for preparing highperformance ACEL devices.The indium tin oxide (ITO) thin film is the most representative electrode in optoelectronic devices. [5] However, its application has many limitations in flexible devices, such as inferior conductivity on polymer substrates and low flexibility. Therefore, various flexible transparent electrode approaches have been tried to substitute ITO thin films in ACEL devices, including singlewalled carbon nanotubes (SWCNTS), silver nanowires (AgNWs), polymer poly(3,4-ethylenedioxythiophene)/polystyrenesulfonate, etc. [6][7][8][9] However, at the same time, it brings problems such as difficulty in preparing large areas and unstable conductivity. In the last decade, a transparent conductive thin film system based on ultrathin metals represented by Ag with oxide/Ag/oxide (OMO) structure, has been attracting attention because of its advantages such as good conductivity at ultra-thin thickness, low cost, and large scale preparation compared to other electrodes. [10] It has been reported for applications such as perovskite solar cells, liquid crystal devices, and Low-E energy saving. [11][12][13] However, to our knowledge, there are no reports of ultrathin metal films used as electrodes for ACEL devices.Two more aspects should be considered before the largescale applications of ultrathin metal films. [14,15] On the one hand, ultrathin metal such as Ag tends to follow islands rather than planar growth modes on high surface energy substrates, resulting in high threshold thicknesses of the Ag films. On the other hand, under elevated temperatures or high humidity, the Ag thin films could dewet from the substrate, resulting in optically lossy and electrical degradation. It was reported that doping metal or oxide in the intermetallic layer might make the OMO thin film more stable in harsh environments. Sugimoto et al. reduced the percolation threshold thickness to 5-6 nm by doping Al in the Ag layer and prepared the AZO/Ag(Al)/AZO thin films, which could withstand 600 °C without changing High performance and durable electrodes are prerequisites for the stable operation of various optoelectronic devices, such as alternating current electroluminescence (ACEL) applications. As for the flexible electrodes based on ultrathin metals, which have attracted much attention in recent years, stability problems as evidenced by optically lossy and electrical degradation of the silver (Ag) layer in the service environment are the key issues to be solved before its prac...