Effect of the polymer overcoat on the performance of the SiNx/SiOx multilayer barrier for OLED gas barrier applications

A SiN_x/SiO_x multi-inorganic barrier shows a low water-vapor transmission rate (WVTR) as the SiN_x/SiO_x pairs increased to five pairs. We found that the WVTR can be significantly reduced after coating a polymer overcoat on the barrier with five SiN_x/SiO_x pairs. Additionally, the inner residual stress can be obviously reduced with the thickness of the polymer overcoat. We conclude that the improvement of the WVTR is ascribed to the reduction of the inner residual stress after coating a polymer overcoat. A WVTR of 1.28 × 10^-7 (g/m²)/day can be achieved after the calcium test time of 1200 hours with a relative humidity of 90% at 60°C.