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Abstract:
We present a detailed Study of the thermal stability of organic thin
films of diindenoperylene encapsulated by sputtered aluminium oxide
layers. We Studied the influence of capping layer thickness,
stoichiometry, and heating rate on the thermal stability of capped
films and their eventual breakdown. Under optimized encapsulation
conditions (thick and stoichiometric capping layer), the organic films
desorb only at temperatures 200 degrees C above the desorption of the
uncapped film. Moreover, the capped organic filius retain their
crystalline order at these elevated temperatures, whereas they would
normally (i.e., uncapped) be in the gas phase. This Study therefore
also shows a way of studying organic materials under temperature
conditions normally inaccessible. Considering results from
complementary techniques, we discuss possible scenarios for the
eventual breakdown. The results have implications for the performance
and long-term stability of organic devices for which stability against
elevated temperatures as well as against exposure to ambient gases is
crucial.