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Electrical calcium test for moisture barrier evaluation for organic devices
S Schubert1, H Klumbies, L Müller-Meskamp
1Dresdener Innovationszentrum für Energieeffizienz, Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr Strasse 1, 01062 Dresden, Germany. sylvio.schubert@iapp.de
The Review of Scientific Instruments
|October 7, 2011
Summary
The electrical calcium test accurately measures water vapor permeation through barrier films. This method accounts for electrode resistance, improving accuracy and enabling detailed analysis of film performance.
Area of Science:
- Materials Science
- Chemical Engineering
- Analytical Chemistry
Background:
- Accurate measurement of water vapor permeation is crucial for barrier film development.
- Existing methods may have limitations in sensitivity or throughput.
- The electrical calcium test offers a high-throughput approach for sensitive permeation measurements.
Purpose of the Study:
- To present and validate an electrical calcium test for measuring water vapor permeation rates.
- To investigate the impact of electrode series resistance on permeation measurements.
- To analyze both steady and transient states of permeation curves.
Main Methods:
- Utilized an electrical calcium test with a sensitivity range of 10^-5 to 15 g/(m^2 d).
- Incorporated electrode series resistance and Fickian diffusion models for data analysis.
- Employed atomic force microscopy (AFM) to study calcium layer morphology.
- Varied electrode materials and calcium layer thickness to assess their influence.
Main Results:
- Demonstrated that neglecting electrode series resistance leads to underestimated permeation rates.
- Successfully fitted both steady and transient states of permeation curves.
- Achieved water vapor transmission rates comparable to coulometric measurements.
- Observed microscopical inhomogeneities in calcium layer morphology during degradation.
Conclusions:
- The electrical calcium test is a sensitive and reliable method for evaluating barrier film permeation.
- Accounting for electrode resistance enhances the accuracy of the electrical calcium test.
- The method provides insights into film morphology and degradation mechanisms.
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