Poor photo-stability of the organic/LiF/Al contact in organic optoelectronic devices

We study the photo-stability of the organic/LiF/Al contacts widely used in organic optoelectronic and photovoltaic devices. Exposing organic/LiF/Al to illumination is found to lead to a decrease in fluorescence (FL) yield of the organic layer. The decrease in FL is found to be due to the diffusion of certain positively charged species, possibly resulting from photochemical interactions with the LiF layer. Evidence of the correlation between the density of the excited states in the organic material and the rate of photo-degradation of the organic/LiF/Al contact is also reported. The results reveal that these widely used contacts suffer poor photo-stability.

Figure optionsDownload as PowerPoint slideHighlights
► The widely used organic/LiF/Al contact suffers poor photo-stability.
► The decrease in FL results from the diffusion of certain positively charged species.
► Rate of photo-degradation correlates with the exciton density in the organic layer.