Growth behavior and improved water–vapor-permeation-barrier properties of 10-nm-thick single Al2O3 layer grown via cyclic chemical vapor deposition on organic light-emitting diodes

• Self-limited nature in C-CVD was observed.
• 10-nm-thick Al2O3 layer with density of 3.298 g/cm3 and 0.46 nm/cycle of deposition rate were grown by C-CVD.
• WVTR of 1.51 × 10−5 (g/m2)/day was obtained at 85 °C and 85% RH and maintained up to 24,000 h of operation time.
• Life-time of OLEDs were measured to be 26,000 h in LT 70.

We have investigated the growth behavior and water vapor permeation barrier properties of cyclic chemical vapor deposition (C-CVD)-grown 10-nm-thick single layer of Al2O3. Al2O3 layers grown by C-CVD showed a high density of 3.298 g/cm3 and were amorphous without grain boundaries. A deposition rate of 0.46 nm/cycle was obtained. The C-CVD system was self-limiting, as in the case of atomic layer deposition, which enables precise control of the thickness of the Al2O3 layer. A water vapor transmission rate of 1.51 × 10−5 (g/m2)/day was obtained from a Ca degradation test performed at 85 °C and 85% relative humidity. Moreover, the performance of organic light-emitting diodes, passivated by a C-CVD-grown 10-nm-thick Al2O3 single layer, was not affected after 24,000 h of turn-on time; this is strong evidence that C-CVD-grown Al2O3 layers effectively prevent water vapor from diffusing into the active organic layer.

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