Encapsulation of Organic Light Emitting Diodes by PDMS Stamping

Abstract

This paper presents results of the improvement of the lifetime of organic light emitting diodes (OLEDs) by encapsulation with polydimethyl siloxane (PDMS). This polymer is very effective in protecting the device from degradation in oxygen and moisture rich environments. This is captured in the results obtained for full immersion and storage tests of encapsulated single layer devices based on MEH:PPV as the active layer. Mechanical tests were carried out to ascertain the strength (adhesion) of the interface between the encapsulating layer and the device cathode material, aluminum (Al) using both centrally-cracked Brazilian Disk, CCBD and force microscopy techniques. The encapsulated devices provided an average of 90 minutes of illumination while the bare devices provided illumination for about 3 minutes. Such a reproducible stamping technique is more appropriate due to the low processing temperatures, inherent flexibility, device compatibility and mechanical robustness at low costs.