Consequences of Roll-Barrier Contact in Roll-to-Roll Processing of a Permeation Barrier

Flexible permeation barriers are a key component for flexibleorganic light emitting diodes and organic solar cells. Roll-torollprocessing is a solution to reduce the costs for barriers.However, usual web handling includes roll-layer contact.This physical contact may be critical for high quality barriers,because the barrier performance deteriorates drasticallywith the introduction of only a few defects. In this work, itis demonstrated that avoiding roll-barrier contact improvesthe barrier performance by at least a factor of 5. To minimizebarrier defects caused by substrate surface irregularities, ahigh quality substrate was used for this study. Due to the highsubstrate quality, a water vapor transmission rate (WVTR) of0.001 g/(m²d) was measured for a 37 nm thick single layerof sputtered zinc tin oxide (ZTO).