A straightforward ambient temperature route to the fabrication of surface silver-metallized polyimide films is described. Silver(I) trifluoromethane sulfonate and a polyimide, derived from 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA) and an equimolar amount of 4,4'-oxydianiline (ODA) and 3,5-diaminobenzoic acid (DABA), were dissolved together in dimethylacetamide. Silver(I)-doped films were prepared at thicknesses of 25-50 microns and depleted of solvent by evaporation. The silver(I)-containing films were then treated with aqueous reducing agents, which brought forth silvered films exhibiting conductivity on the order of bulk polycrystalline silver and good specular reflectivity.

Silver neodecanoate is sensitive to both ultra violet light (UV) and heat, and is a good inkjet printing precursor when dissolved in xylene. We have studied the electrical properties of inkjet printed silver samples, derived from silver neodecanoate ink, and investigated the influence of UV treatment before thermal curing the silver samples. In addition we have studied the influence of thermal pre-treatment on the printed samples. Thermally cured printed tracks and pads show minimum resistivity of approximately 3 x bulk silver. Their microstructure shows that the silver salt has converted to an interconnected network of silver nanoparticles after curing. The resistance of the printed tracks are shown to relate to the connectivity of the resulting sintered nanoparticle network as measured by the ratio of the sintered neck diameter to the original particle diameter.

We report a new integration approach to produce arrays of ZnO microcrystals for optoelectronic and photovoltaic applications. Demonstrated applications are n-ZnO/p-GaN heterojunction LEDs and photovoltaic cells. The integration process uses an oxygen plasma treatment in combination with a photoresist pattern on Magnesium doped GaN substrates to define a narrow sub-100nm width nucleation region. ZnO is synthesized in the defined areas by a hydrothermal technique using zinc acetate and hexamethylenetetramine precursors. Nucleation is followed by lateral epitaxial overgrowth producing single crystal disks of ZnO. The process provides control over the dimension and location of the ZnO crystals. The quality of the patterned ZnO is high; the commonly observed defect related emission in the electroluminescence spectra is suppressed and a single near-band-edge UV peak is observed. Transfer printing of the ZnO microcrystals onto a flexible substrate is also demonstrated in the context of transparent flexible electronics.

In recent years, inkjet printing has become an important technology for many applications, such as organic electronics, nanotechnology, and tissue engineering, on account of its ability to precisely deposit pico litre volumes of solutions or suspensions, including polymers and metal nanoparticles, in well-defined patterns [1]. In this work we focus on the electrical performance of PEDOT:PSS conductors inkjet printed onto natural rubber latex and the effect of mechanical deformation on conductor integrity and electrical performance. 1. B.-J de Gans, P. C. Duineveld and U. S. Schubert, Adv. Mater., 16, (2004).

Large area deformable macroelectronics, such as flexible display, smart bandage, electronic textile, have to withstand various modes of deformation (e.g., bending, twisting and stretching). Such electronic systems usually are composed of inorganic parts with limited deformability, and organic parts which can sustain large deformations. Because of the elastic nature of elastomers, these materials are often used as substrates for the specific applications mentioned above. In order to fulfill the demand of deformability, many concepts have been developed. One of these concepts consists of small rigid islands with active devices or individual thin chips which are interconnected by thin metal conductor lines. All rigid components are placed on the small islands to ensure that the strains acting on these brittle components are small when the structure is subjected to a large deformation. Since the thin conductor lines have to withstand all these deformations, a proper structural design is necessary to avoid losing structural integrity and electrical functionality during this deformation. Several technologies have been proposed in recent years, such as in-plane patterned metal conductors, out-of-plane wrinkling metal films, and conductive polymers or liquid alloys. It has been reported that by depositing a thin metal strip with a thickness of few nanometers on an elastomeric substrate, the elongation of the metal can go up to 50% while the strip remains conductive. Upon large strain, the elastic deformation of the elastomeric substrate causes local debondings of the metal film coevolving with strain localizations. Thanks to this coevolved process, even a �straight� line, deposited on a polymer substrate, is stretchable. However, a drawback of this unique characteristic is that the resistance of the thin metal film changes with elongation, which might be a disadvantage for certain applications. Another approach for having a stable resistance is to use bulk metal conductors. Compared to a freestanding bulk metal straight line which ruptures at strains of 1%˜2%, an in-plane patterned horseshoe metal conductor can be stretched up to 100% with a stable resistance before electrical failure. This paper demonstrates a novel in-plane patterned zigzag structure, with resistance independent of elongation before metal rupture, which can be stretched beyond 40%. The advantage compared to the horseshoe is that due to the geometrical design, the in-plane zigzag structural interconnects can be applied in a fine pitch microelectronic device. The experimental observations by both scanning electron microscopy micrographs and resistance measurements show that there is no significant local necking in either the transverse or the thickness direction at the metal breakdown area. Micrographs and simulation results show that a debonding occurs due to the local twisting of a metal interconnect, out-of-plane peeling and strain localized at the crest of a zigzag structure.