Silver Diffusion in Organic Optoelectronic Devices: Deposition-Related Processes versus Secondary Ion Mass Spectrometry Analysis Artifacts

The development of organic optoelectronic devices relies on controlling interfaces during thin-film deposition and requires an accurate characterization of the film composition at these interfaces. Dynamic secondary ion mass spectrometry (SIMS) is widely used to investigate multilayer thin-film structures. Routine analysis protocols are well established for classical semiconductor samples, but for organic or mixed metallic–organic samples the limitations of the technique are less well established. In the current work, low-energy dynamic SIMS is used on metal–organic multilayered model structures similar to those in organic optoelectronic devices to study the origin of diffusion of metal into the organic layer (e.g., irradiation-induced diffusion during SIMS analysis or during the deposition process). Samples contain silver and organic compounds sequentially deposited by thermal evaporation in vacuum onto a Si substrate. They are analyzed using a 250 eV to 1 keV Cs⁺ primary ion beam. It is found that the mixing of silver into the organic layer depends on the impact energy and the conditions for sample preparation. This irradiation effect can be minimized by a back-side depth profiling approach, which was developed in this work. By applying this method, it is shown that some silver is likely to diffuse into the organic layers during the deposition process

Additional file 1: Figure S1. of Use of next generation sequencing data to develop a qPCR method for specific detection of EU-unauthorized genetically modified Bacillus subtilis overproducing riboflavin

Sequence of B. subtilis subsp. subtilis str. 168 genome sequence [Genbank:CP010052.1] corresponding to the region containing part of Contig00019 and Contig00022. There is a gap of 37 basepairs (uncoloured region in the figure) between Contig00019 (pink region in figure) and Contig00022 (yellow region in figure), when aligning the obtained contigs to B. subtilis subsp. subtilis str. 168 genome sequence [Genbank:CP010052.1]. PCR and sequence analysis were used to confirm that the genomic regions present on both contigs are indeed adjacent in the GM-Bacillus genome. Hereto, primers Scaf-19-F3-seq (positioned on Contig00019, indicated in green) and Scaf-22-R-seq (positioned on Contig00022, indicated in blue) were used to amplify the flanking regions of the junction between Contig00019 and Contig00022. Subsequently, the obtained PCR fragment was sequenced. (PDF 101 kb