Berlin 2015 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 39: Poster Session II

DS 39.33: Poster

Donnerstag, 19. März 2015, 16:00–18:30, Poster F

Multilayer Aluminum Thin Films as Effective Encapsulation for Flexible Organic Devices — •Felix Dollinger, Frederik Nehm, Karl Leo, and Lars Müller-Meskamp — Institut für Angewandte Photophysik, Technische Universität Dresden, Deutschland

Thin film organic devices like organic solar cells require encapsulation against water vapor. Depending on the device, water vapor transmission rates (WVTR) in the range of 10⁻⁵g/m²·day are needed for lifetimes of at least five years. In this work we aim at improving the encapsulation properties of opaque vacuum-evaporated aluminum back-electrodes to fulfill these barrier requirements.

Water diffusion through aluminum layers is defect-driven. To reduce defect densities, the growth behavior of the aluminum layer is modified by underlying metallic seed-layers which have shown improved performance in transparent metal thin-film electrodes.

Significant improvement of WVTR can be achieved with multilayer structures. Thin interlayers that decouple the defect positions in consecutive aluminum layers provide long and tortuous diffusion-paths for water-molecules. In our study, we use the electrical calcium-test to investigate stacks of aluminum layers with various interlayers with respect to steady-state WVTR and lag-time. The interlayers consist of different planarizing, diffusion-limiting, or getter materials that absorb water-molecules as they diffuse through the barrier.

These optimized aluminum multilayers are promising candidates for organic thin-film encapsulation.