In this study, a composite layer of atomic-layer-deposition-grown Al2O3 (ALD Al2O3) on chemical-vapor-deposition-grown graphene (CVD graphene) was fabricated for encapsulation of an organic light-emitting diode (OLED). NO2 functionalization was adopted to improve the nucleation and film quality of the ALD Al2O3 on CVD graphene, and the resulting Al2O3 on NO2-functionalized graphene exhibited increased film density and decreased porosity and roughness compared to that without functionalization; these improved properties satisfy the requirements for encapsulation layers. In addition, the water vapor barrier property of the Al2O3 and graphene composite layer was improved compared with that of a single Al2O3 layer; a single graphene layer did not exhibit the barrier property because of inherent defects. According to the laminate theory, the calculated water vapor transmission rate of graphene in the composite layer was about 2 × 10−3 g/m2·day, which is much greater than that of the single graphene layer without Al2O3 because of the combinational effects of the Al2O3 layer. Furthermore, the permeability of graphene was almost unchanged before and after the application of bending stress because of its mechanical durability and flexibility. This ALD Al2O3/graphene composite is expected to be a promising encapsulation layer for future flexible OLED devices.
Bibliographical noteFunding Information:
This research was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2014R1A1A2059845), Center for Integrated Smart Sensors funded by the Ministry of Science, ICT & Future Planning as Global Frontier Project (CISS-2011-0031848), Korea Evaluation Institute of Industrial Technology (KEIT) funded by the Ministry of Trade, Industry and Energy (MOTIE) (Project No. 10050296, Large scale (Over 8?) synthesis and evaluation technology of 2-dimensional chalcogenides for next-generation electronic devices), and a National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIP No. NRF-2014R1A2A1A11052588).
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All Science Journal Classification (ASJC) codes
- Materials Science(all)