Improved mechanical properties of Al2O3/acrylic laminates for flexible thin film encapsulation by introducing wavy interfaces

Thin film encapsulation (TFE) with high barrier performance and mechanical reliability is essential and chal-lenging for the reliable operation of flexible organic light-emitting diodes (OLEDs). To break the trade-off relationship between high flexibility and low permeability, this work proposed an Al2O3/acrylic multi-layered structure with wavy stacking interfaces to reduce the tensile strain of the brittle Al2O3 film under bending. It was found from simulation analysis that 3-dyad wavy Al2O3/acrylic multi-layered structures with periods in the ranges of 500-1500 nm and amplitudes in the ranges of 600-1600 nm were preferred due to a smaller maximum stress under bending. A novel approach to generate wavy structures with controllable periods and amplitudes was proposed by combining argon plasma treatment and soft-lithography. The findings suggest that the water vapor transmission rate (WVTR) of a 3-dyad wavy Al2O3/acrylic multi-layer was 3.18 x 10-5 g/m2/day after 100-iteration bending with the bending radius of 1 cm, corresponding to the tensile strain exceeding 1.09%. The lifetime of OLED encapsulated using corresponding Al2O3/acrylic multi-layers with wavy structures and under the same bending condition was around 50 h, showing a 40% increase compared to that without wavy structures. The wavy structures can improve the mechanical properties of Al2O3/acrylic remarkably.

Automated summary

In order to overcome the trade-off relationship between high flexibility and low permeability, a multi-layered structure of Al2O3/acrylic with wavy stacking interfaces was proposed. The wavy structures were generated by combining argon plasma treatment and soft-lithography. The wavy structures improved the mechanical properties of Al2O3/acrylic and increased the lifetime of OLEDs under bending conditions.