Improvement of barrier performance in thin film encapsulation for organic light-emitting diodes by a prior planarization process

The organic/inorganic hybrid barriers were fabricated to encapsulate the organic light-emitting diodes. Al
₂
O
₃
as inorganic layer was deposited by atomic layer deposition (ALD) and polydimethoxysilane (PDMS) as organic layer was prepared by the spin-coating process. It was found that the optimized encapsulation structure with a prior planarization process had a better barrier performance with a lower water vapor transmission rate improved effectively from 4.95 × 10
^-1
gm
^-2
day
^-1
of Al
₂
O3/PDMS films to 7.30 × 10
^-3
gm
^-2
day
^-1
of the hybrid PDMS/Al
₂
O
₃
/PDMS films at 60 °C and a relative humidity of 90% and a longer luminance decay time. These imparovements were attributed to the surface planarization of encapsulation basement including the coverage of particles by the prior spin-coating process, reducing the defects of inorganic film in process, and the hydrophobic surface of the outermost polymer lowering the adsorption of water vapor.