Reliable thin film encapsulation for organic light emitting diodes grown by low-temperature atomic layer deposition

Abstract

We report on highly efficient gas diffusion barriers for organic light emitting diodes (OLEDs). Nanolaminate (NL) structures composed of alternating Al2O3 and ZrO2 sublayers grown by atomic layer deposition at 80 °C are used to realize long-term stable OLED devices. While the brightness of phosphorescent p-i-n OLEDs sealed by a single Al2O3 layer drops to 85% of the initial luminance of 1000 cd/m2 after 1000 h of continuous operation, OLEDs encapsulated with the NL retain more than 95% of their brightness. An extrapolated device lifetime substantially in excess of 10 000 h can be achieved, clearly proving the suitability of the NLs as highly dense and reliable thin film encapsulation of sensitive organic electronic devices.

Highly reliable hybrid nano-stratified moisture barrier for encapsulating flexible OLEDs

“…2b is a schematic diagram of the Ca pad. With a normalized conductance vs time graph, the WVTR of the barrier can be calculated [16]. Fig.…”

“…This multi-barrier permeation mechanism has been discussed by Graff et al [15]. In contrast, the nanolaminate barrier just uses inorganic layers which are laminated by other kinds of inorganic materials on a nanoscale level [16]. Because of its excellent gas barrier property, it has a low WVTR at the same thickness of a single inorganic barrier [17].…”

Thin film encapsulation for organic light-emitting diodes using inorganic/organic hybrid layers by atomic layer deposition

“…A denser ZrAlxOyaluminate phase with higher packing density could be formed at the interfaces between Al 2 O 3 and ZrO 2 , leading to a densification at the Al 2 O 3 /ZrO 2 interfaces [18,19]. Because the permeation rate for gasses such as water vapor depends on the density of the material, even a small amount of water can enter into the device through the thin film.…”

Cathode encapsulation of organic light emitting diodes by atomic layer deposited Al2O3 films and Al2O3/a-SiNx:H stacks

“…[7][8][9] It is therefore plausible to choose ALD to conformally cover of the particles responsible for the pinholes present on the cathode. Several studies have already shown that Al 2 O 3 synthesized by ALD is a promising candidate for OLED encapsulation, [10][11][12][13][14][15][16][17] however in these contributions the focus is on the engineering of barrier layers on polymer substrates. In the present work, we evaluate the inorganic barrier films in terms of intrinsic barrier performance as well as in terms of particle/defect conformal coverage a) Author to whom correspondence should be addressed; electronic mail: m.creatore@tue.nl 18 as described below.…”