This paper presents the results of atomic force microscopy (AFM) measurements of the adhesion between materials relevant to organic solar cells and organic light-emitting devices. The adhesion is quantified using pull-off forces obtained for organic-organic, organic-inorganic, and inorganic-inorganic interfaces. The measured pull-off forces and surface parameters are then incorporated into theoretical models for the estimation of surface energies. The implications of the results are then discussed for the design of enhanced robustness in organic electronic structures.

Atomic diffusion bonding of wafers with thin nanocrystalline metal films J. Vac. Sci. Technol. B 28, 706 (2010); 10.1116/1.3437515 High-adhesive back side metallization of ultrathin wafersThis paper presents the results of a combined experimental and theoretical study of adhesion in cold-welded Au-Ag interfaces that are relevant to the fabrication of organic electronic structures. Focused ion beam /transmission electron microscopy and electron energy loss spectroscopy techniques are used to reveal interfacial impurities associated with the cold welding of nanoscale Au and Ag thin films. A theoretical model is also developed and used to predict the contact profiles around impurities between cold-welded thin films. The model is shown to provide new insights into how adhesion affects the surface contacts that occur during cold welding. The implications of the results are then discussed for the design of cold-welding processes.

The role of thermal gradients and their attendant mechanical stresses in the overall stability of organic electronic devices has been elucidated through the occurrence of spiral shaped blisters that develop on the surface of suitably biased polymer light emitting diodes. A model based on the spontaneous disordering (or ordering) of polymeric thin film systems has been used to explain the formation and growth of these blisters. The model is shown to provide insights into how thermal stresses affect the overall stability of organic electronic devices. The implications of the results are then discussed for the design of flexible organic electronic devices.

No abstract

Thermal annealing induced bicontinuous networks in bulk heterojunction solar cells and bipolar field-effect transistors Appl.This paper presents the evidence of growth of dendrites during the annealing of poly (3-hexylthiophene) and [6,6]-phenyl C 61 -butyric acid methyl ester (P3HT:PCBM) blends that are being explored for potential applications in bulk heterojunction polymer solar cells. These dendrites were observed in high resolution scanning electron microscopy to have morphologies that depend on the annealing temperature. Consistent with a recent eutectic phase diagram, the dendrites were not observed at 200 C. The observations were explained by considering the effects of temperature on the kinetics of phase nucleation and growth in P3HT: PCBM blends. The implications of the results are also discussed for the stability of electrical properties in bulk heterojunction solar cells.