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.