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The optical and barrier properties of thin-film encapsulations (TFEs) for top-emitting organic light-emitting diodes (TEOLEDs) were investigated using TFEs fabricated by stacking multiple sets of inorganic–organic layers. The inorganic moisture barrier layers were prepared by atomic layer deposition (ALD) of Al2O3 using trimethylaluminum (TMA) and O3 as precursors and are shown to be efficient barriers against gases and vapors. The organic alucone layers were produced by molecular layer deposition (MLD) using TMA and ethylene glycol as precursors. The [Al2O3:Alucone] ALD/MLD films were used because their adjustable inorganic–organic nanolaminate composition allows for the tuning of the optical properties, thereby enhancing their application potential for the design and fabrication of high performance light out-coupling structures for TEOLEDs. By carefully adjusting the relative thickness ratio of the inorganic–organic encapsulation materials, optimized light extraction was achieved and the films not only maintained their high moisture barrier strength but also showed excellent optical performance.

The investigations reported in this study were carried out to determine the feasibility and properties of alucone/Al2O3 hybrid nanolaminate films for thin film encapsulation (TFE) at low temperature, using an integrated molecular layer deposition (MLD) and atomic layer deposition (ALD) process. The combination of alucone (MLD) and Al2O3 (ALD), with O3 serving as the oxidant in place of conventional H2O, has been evaluated experimentally. In our studies, O3-based encapsulation layers were observed to be smoother, displaying an average roughness of 0.342 ± 0.016 nm with three laminate layers. However, H2O-based laminates showed a much higher roughness of 0.843 ± 0.024 nm under identical conditions. Estimates of water vapor transmission rate (WVTR) yielded significantly better results for O3-based laminates, with values decreasing linearly from 3.22 × 10−3 g m−2 per day to 2.37 × 10−5 g m−2 per day as the number of laminate layers increased from one to three, while a gentle decline trend from 1.83 × 10−3 g m−2 per day to 5.92 × 10−4 g m−2 per day was obtained for the H2O-based laminate. This indicates that the hybrid nanolaminates exhibited improved water barrier properties when O3 was used as the oxidant instead of H2O. In particular, the O3-based films did not decrease the performance of organic light-emitting diodes (OLEDs). In fact, the lifetime of OLEDs with O3-based encapsulation was approximately two-fold longer than the H2O-based encapsulation. Thus, we believe that the alucone/Al2O3 hybrid encapsulation film, in which O3 serves as the oxidant, is a promising candidate for use in future OLED applications.

The properties of Al2O3 encapsulation layers prepared by atomic layer deposition were investigated as a function of film thickness. By using a short pumping gas time (PGT) and a low viscosity gas, high-quality films for the encapsulation of organic light-emitting diodes were obtained. The encapsulation properties could be improved by decreasing the PGT and using a low viscosity gas as the precursor at a low temperature. The water vapor transmission rate of the film could reach up to 4 × 10–3g/m2/day. In addition, atomic force microscopy images and investigations of the refractive index showed that the film properties did not change substantially with increasing thickness. Furthermore, by optimizing the PGT, the total deposition time could be effectively reduced.

This paper reported a low-temperature thin film encapsulation (TFE) process based on atomic layer deposition Al2O3 layer for top-emission organic light-emitting devices (TE-OLEDs). The barrier characteristics of both H2O-based and O3-based Al2O3 films were investigated. O3-based Al2O3 TFE showed lower water vapor transmission rate (WVTR) of 8.7 × 10−6 g/m2 day and longer continuous operation lifetime of 5 folds compared to the device with H2O-based Al2O3 TFE under identical environmental and driving conditions. Furthermore, the extraction of emitting light of the devices with barrier layer was enhanced compared to the bared one. The theory simulation data were consistent with our experimental results and showed the potential for the design of TFE structures optimized for enhancing light transmission.