| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Thin Films | Monday Sessions |
| Session TF-MoM |
| Session: | Advances/Innovation in Synthesis & Characterization |
| Presenter: | Céline Noël, University of Namur, Belgium |
| Authors: | F. Noël, University of Namur, Belgium L. El Fissi, Université Catholique de Louvain L.A. Francis, Université Catholique de Louvain L. Houssiau, University of Namur, Belgium |
| Correspondent: | Click to Email |
In the last few years, growing attention has been brought to devices based on hybrid (organic/inorganic) multilayered materials as they allow for highly versatile properties, such as tunable optical and electronic features, malleability, transparency and cost-efficiency that could find applications in a large variety of devices such as OPVs, OLEDs, sensors, microfluidics, fuel cells, etc. . Forthcoming technological advances will require detailed knowledge of layers and interfaces composition and morphology in order to optimize device efficiency, stability, processing conditions.
ToF-SIMS is a well-suited technique to obtain key information such as the in-depth molecular composition of each layer and diffusion at the interfaces. However, for hybrid materials, depth profiling remains challenging as ion sources which are efficient on organic materials are generally not efficient on inorganic ones. Numerous dynamic-SIMS studies of interfacial migration between organic/inorganic layers have been reported, but no molecular signal could be monitored. Recently, low-energy (500 eV) Cs+ ions were shown to possibly offer a reliable solution for depth-profiling hybrid systems [1]. Using this novel approach, the present work presents molecular depth-profiling on complex OLEDs interfaced materials showing that each layer, until the substrate, could be successfully identified by its specific molecular signal within a reasonable sputtering time.
In parallel, oxide/polymer hybrid materials were investigated with future applications in microfluidics, BioMEMS and lab-on-chip devices. Samples consisted of TiO2 or Al2O3 coating on three different polymers, namely cyclic olefin copolymer (COC), polyimide (PI) and SU-8 (a negative photoresist). Again, all samples were easily depth profiled by low-energy Cs+, with characteristic molecular fragments monitored on each polymer even after the oxide layer is sputtered. This again proves that low-energy Cs+ is an efficient solution to depth profile hybrid materials. We also compared metal diffusion in different oxides coating and polymers. Issues like homogeneity, contamination or non-stochiometry near the interface could be addressed by ToF-SIMS analyses; matrix effects and ion beam induced modifications were discussed based on complementary XPS measurements.
With the development of new technologies, an increasing number of applications are expected to require in-depth molecular information of organic/inorganic materials. The present work shows how ToF-SIMS can answer this demand, opening the way for the characterization of such novel applied materials.
[1] C. Noël and L. Houssiau, J Am Soc Mass Spectrom, 2016. 27(5): p. 908-16.