We report Fe-42%Ni as a novel high-performance substrate for a-IGZO TFT fabrication after evaluating 8 different metals for chemical compatibility, mechanical flexing and dimensional stability. Excellent flexibility and rollability indicates that Fe-42%Ni would be a good choice as flexible substrate for R2R process. Pre-annealing process for stabilizing the substrate is studied and applied to the Fe-42%Ni foil before TFT fabrication. Staggered bottom gate a-IGZO TFTs which were fabricated on this substrate have field effect mobility of 12 cm2/V.s, threshold voltage of 2V, sub-threshold swing of 0.6V/decade and on/off current ratio exceeding 107.

We report our fabrication of pentacene field effect transistors (FETs) based on a vacuum processed and e-beam cured polymer electrolyte (i.e., tripropylene glycol diacrylate (TRPGDA)) as a gate dielectric layer on flexible wide web substrates. The deposition of the semiconductor and gate insulator layers is carried out in Oxford's roll-to-roll vacuum web processing facility and could be combined in-line with roll-to-roll pattern metallization. The aim of the work is to demonstrate the ability to create all-evaporated transistors, exploiting the kind of technologies at present extensively used in the food packaging industry, for example, in which all layers can be deposited at high web speeds. Ours is a room temperature and a solvent-free method with an ultrahigh deposition rate (web speeds in excess of 100 m/min are possible).

The performance of the pentacene and the polymer dielectric materials within devices was investigated, demonstrating (1) the ability to deposit good quality pentacene layers in the roll-to-roll environment and (2) the importance of the e-beam curing conditions of the dielectric layer on the performance of the organic FET devices. This deposition route creates a smooth, pin-hole-free dielectric layer as it is deposited onto the substrate as a monomeric liquid, before curing, and there is no mass-loss such as in solvent-based deposition processes. These devices have a 250 μm channel length and an aspect ratio of 16. No self-assembled monolayer (SAM) or other surface modification had been applied to the insulator layer to achieve these properties.

The tuning of the transistors' operating voltage and output characteristics was feasible through the ease of control of the polymer dielectric thickness achieving a threshold voltage of less than 10 V. On/off ratio in excess of 103, and mobility = 0.1 cm2V-1s-1 have been achieved.

The ability to integrate such a high deposition rate polymer process, into a single step, multilayer, vacuum deposition process with conventional vacuum deposition sources provides a possible route to low cost and large area electronic device processing.

Printed electronics is a seminal technology for the production of simple disposable electronic products. In comparison to conventional silicon electronics it offers the possibility to use potentially cheap materials (e.g. polymers) which can be processed as solutions or dispersions by means of highly productive mass printing technologies. One main aim is the production of fully mass printed electronic circuits for the identification of single items, which should not cost more than one cent per tag. For the realization several challenges have to be clarified. On the one hand the performance of the - often organic - materials has to be increased in interaction with the used printing technologies. On the other hand the printing methods themselves have to be adapted and continuously improved. Alternatively, new approaches for the preparation of structured thin films have to be developed. This paper introduces a new technique for the production of source/drain electrodes with high resolution.

In this contribution, we report on the optimization of a metal-organic decomposition (MOD) ink based on silver(I) complexes by a systematic variation of the ink formulation. As a result, three different ink concepts turned out to be printable and resulting in a sufficiently high contour definition, layer homogeneity, and conductivity. The ink concepts include increase of the solid load, the usage of N-methyl-2-pyrrolidone (NMP) as a humectant with low vapor pressure, addition of co-solvents such as diethylene glycole and addition of sodium lauryl sulfate (SLS) as stabilizing ligand. It turns out that, for silver precursor concentrations of 40 wt%, the addition of 1 wt% SLS to aqueous inks leads to elevated conductivity up to 3.2x107 Sm-1 at maintained printability and an improved contour definition with respect to pure aqueous inks.

Foils from the ethylene-tetrafluoroethylene (ETFE) copolymer are used as transparent, humidity resistant and UV-stabile facade and roof coverings, e.g. for stadia, indoor swimming pools or greenhouses [1]. With pneumatically supported cushions, large translucent structures can be realized. Until now, they are assembled through a thermal welding process [2]. The development of welding techniques using laser irradiation is under way.

Laser welding of transparent polymer foils requires an optical absorber placed in the interface between the two welding pairs. Usually, dye molecules with absorption properties adapted to the laser wavelength are used as absorbers. At a well-defined temperature, the dye molecules will be chemically modified, and transparent laser welding seams can be achieved. To get reproducible laser welding results, a homogenous layer of absorbent molecules or materials at the welding interface have to be realized, which is often very hard to achieve by wet deposition of dye molecules dispersed in a solution.

In our contribution, we report on an inkjet printing system that can be mounted on a R2R manufacturing setup. The main challenge to this approach is to find the right ink that is compatible with this highly hydrophobic ETFE foil. Therefore, both the pretreatment of the substrate as well as the utilization of different inkjet technologies are dealt with in this contribution. It is demonstrated that the inkjet printing of a laser absorbent ink in a defined way onto the substrate is possible.

For quality assurance, an optical inspection system has been developed to ensure a proper deposition of material. This ensures the quality control for the inkjet printing process of the special functional material. In that part the results of the comparison of the use of a dedicated 14‑bit grey level CCD line camera is compared to a high quality webcam.

Laser irradiation of the foil with printed laser absorbent lines together with the untreated joining partner was performed by a continuous wave diode laser at a wavelength of 808 nm using a defocused laser spot. A nearly transparent welding seam was achieved. Mechanical tensile tests of the laser welding seams have demonstrated that their tensile strength is comparable to conventional thermal welding seams.

In the last years more and more effort has been put into the development of thin-film organic solar cells using conductive and semi-conductive polymers. A great advantage of these polymers is the possibility to deposit them in high throughput print and coating processes. This feature provides huge potential for future production of low cost photovoltaics. While TCO layers form the transparent front contact, polymers are used for the buildup of the active layer and the design of the interface between active layer and front contact. The polymer materials have to be patterned in order to allow for a row connection of the solar cell work (typically by structured deposition, e.g. printing). In addition the bulk hetero junction (BHJ) of the active layer consisting of poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) requires an annealing step to optimize the layers structure and therewith the efficiency of the solar cell (typically by thermal treatment, e.g. oven). 3D-Micromac used ultra-short pulsed lasers to evaluate the applicability of various wavelengths for the selective ablation of the BHJ consisting of P3HT:PCBM on top of a Poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and indium tin oxide (ITO) film system on glass substrates. The process of laser annealing was investigated using a short-pulsed laser with a wavelength close to the absorption maxima of the BHJ.