The improvement of thin film barrier performances of organic–inorganic hybrid nanolaminates employing a low-temperature MLD/ALD method

Abstract

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.