A correlation study between the total permeated water vapor and lifetime of an encapsulated OPV

Barrier films play a critical role in the packaging and protection of solar cells, especially organic photovoltaics. While high performance barrier films are needed to limit the ingress of water vapor and oxygen into the cells, little has been done to correlate the performance of such cells with their barrier films. In this work, a study is presented with correlates the shelf lifetime of an encapsulated organic solar cells with barrier films having differing water vapor transmission rates. The study shows that overall barrier performance of multilayer thin films and the extended shelf lifetime of encapsulated organic solar cells can be related through the calculation of the total permeated water vapor through the barrier films. The total permeated water vapor was calculated separately in the transient and steady-state regions considering the lag time effect of the multilayer barriers. The efficiency of pentacene/C₆₀-based solar cells encapsulated with one or two pairs of SiN_X/parylene dropped to 50% after permeation of about 1.63 g/m² of water vapor regardless of transmission rate. From these calculations, the lifetime of encapsulated devices with three pairs are predicted.