senstive to the permeated moisture or oxygen due to the simultaneous intrinstic instability and the broad bandgap energies, which has become the bottleneck of the next-generation display technologies. [6,7] The reliable encapsulation structures would be necessary for the flexible displays to reach the designed lifespan, and the water vapor transmission rate (WVTR) of which ought to be below 10 -5 g m −2 day −1 in the ambient. [8,9] Although the glass/metal lids could meet the requirement of the barrier property, they are not compatible with the flexible display when the external strain was applied. Thus, thin film encapsulation (TFE) has become an attractive method which could provide the flexible encapsulation layer over the large-area displays. [10][11][12] Various inorganic films (such as SiN x , SiO 2 , SiO x N y ) have been applied to the encapsulation of flexible displays via thermal evaporation, [13] plasma-enhanced chemical vapor deposition, [14,15] etc. However, the low-temperature process is needed to protect the organic materials from the thermal damage, which leads to the decreasing film density. Among the various thin film deposition methods, atomic layer deposition (ALD) possesses the advantages of precise thickness control at atomic level, excellent uniformity, and conformality over large areas. [16][17][18] Besides, the pinhole-free films with high densification could be obtained with low-temperature ALD process. [19] Thus, ALD-based encapsulation structures have been developed to be applied to the flexible displays. [20][21][22] As for the inorganic barriers, Choi et al. revealed that with the thickening of the barrier layer, the WVTR value would decrease and saturate at a specific thickness. [23] However, the barrier property would degrade with the further increase of the film thickness. Behrendt et al. found that as for the inorganic barriers with several hundred nanometers, the delamination or cracking behavior occurred around the particle contamination when stored in the damp heat condition. [24] Chen et al. revealed that the increasing stored elastic energy aroused by the increasing film thickness and residual stress led to mechanical instability and degraded barrier property. [25,26] Besides, George et al. demonstrated that the thicker inorganic films possessed the significantly decreased critical tensile or compressive strain, which was not beneficial for them to be applied to the encapsulation of flexible displays. [27] The inorganic/organic multilayers have been proposed to improve the flexibility as well as maintain the barrier property In this work, the polydimethylsiloxane (PDMS)/Al 2 O 3 nanolaminates with optimized sublayer thickness and interfaces have been developed to protect the organic light-emitting didoes (OLEDs) from the erosion of the moisture in the ambient. The O 2 plasma pretreatment is used to tune the wettability of the ultrathin PDMS sublayers with nanoscale thickness, and the distinct interfaces between the Al 2 O 3 and PDMS sublayers are obtained. The electrical cal...