Marja VilkmanVTT Technical Research Centre of Finland | vtt · Printed Functionality
Marja Vilkman
D.Sc. (Tech.)
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27
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Publications (27)
Lignin is a nature’s wonder most abundant aromatic biopolymer and a promising precursor for a wide range of sustainable carbon materials (CMs). However, the effects of lignin structural heterogeneity on the properties and performance of lignin-based CMs are still poorly understood. In this paper, we address the influence of the lignin structural he...
Sustainability and circular economy cover the principles of designing out waste and pollution, keeping products and materials in use, and regenerating natural systems. Due to global trends (eg. increasing e‐waste and material consumption) and global sustainability goals also electronics industry has to consider how to increase sustainability in its...
High registration accuracy in roll-to-roll (R2R) processes enables high throughput production of complex multilayer devices in printed and flexible electronics. Three different topics need to be optimized, in order to maximize the registration accuracy: i) stability of the substrate dimensions, ii) mechanical accuracy of the printing press, and iii...
The comparison of solution processed organic photovoltaics (OPVs) with two roll-to-roll coated electron transport layers (ETL), as well as printed grid or solid back electrodes provides insight into the future of R2R fabricated architectures. The variation in performance of the R2R slot-die coated zinc oxide (ZnO) versus the tin oxide (SnO2), showe...
Understanding the phenomena at interfaces is crucial for producing efficient and stable flexible organic solar cell modules. Minimized energy barriers enable efficient charge transfer and good adhesion allows mechanical and environmental stability, and thus increased lifetime. We utilize here the inverted organic solar module stack and standard pho...
Indene-C60-bisadduct (ICBA) can represent an excellent choice as an acceptor of organic solar cells due to the, at most, similar cost, higher efficiency, and higher open-circuit voltage (VOC) obtained in small-scale devices compared to phenyl[60]butyrate methyl ester ([60]PCBM). We have investigated ICBA in printed solar cells and assessed the upsc...
We demonstrate the production of organic bottom gate transistors with self-aligned electrodes, using only continuous roll-to-roll (R2R) techniques. The self-alignment allows accurate <5 µm layer-to-layer registration, which is usually a challenge in high-speed R2R environments as the standard registration methods are limited to the millimeter range...
We describe the fabrication of roll-to-roll (R2R) printed organic photovoltaic (OPV) modules using gravure printing and rotary screen-printing processes. These two-dimensional printing techniques are differentiating factor from coated OPVs enabling the direct patterning of arbitrarily shaped and sized features into visual shape and, increasing the...
We demonstrate a high throughput roll-to-roll process for preparing organic top gate transistors with metallic electrodes on a flexible substrate. The source and drain electrodes are prepared by patterning a roll-to-roll evaporated silver layer with a printable etchant. The etching step is done by a screen printing process with a novel triblock cop...
We present a gravure printing process for zinc oxide (ZnO) nanoparticle ink to be used as a hole-blocking layer in inverted organic solar cells, enabling the production of patterned devices with freedom of design. The printability of the ink is optimized in a pilot-scale roll-to-roll (R2R) process, leading to smooth layers having a thickness of few...
Roll-processed, indium tin oxide (ITO)-free, flexible, organic tandem solar cells and modules have been realized and used in round-robin studies as well as in parallel inter-laboratory stability studies. The tandem cells/modules show no significant difference in comparison to their single-junction counterparts and the use of round-robin studies as...
We present a cost analysis based on state of the art printing and coating processes to fully encapsulated, flexible ITO- and vacuum-free polymer solar cell modules. Manufacturing data for both single junctions and tandem junctions are presented and analyzed. Within this calculation the most expensive layers and processing steps are identified. Base...
Inline printing and coating methods have been demonstrated to enable a high technical yield of fully roll-to-roll processed polymer tandem solar cell modules. We demonstrate generality by employing different material sets and also describe how the ink systems must be carefully co-developed in order to reach the ambitious objective of a fully printe...
Room temperature substrate-facilitated sintering of nanoparticles is demonstrated using commercially available silver nanoparticle ink and inkjet printing substrates. The sintering mechanism is based on the chemical removal of the nanoparticle stabilizing ligand and is shown to provide conductivity above one-fourth that of bulk silver. A novel appr...
We show that acid-base complexation of rod-like poly(2,5-pyridine) (PPY) by bis(trifluoromethane) sulfonimide (TFSI) leads to highly-ordered lamellar self-assemblies in the hydrated films and shows relatively high room temperature conductivity of ca. 10(-4) S/cm. Thin films with different nominal degrees of complexation were studied using X-ray dif...
Two European Union-funded projects are developing roll-to-roll-based fabrication technologies for commercialization of printed electronics and optics applications. The first project, called Flexible Autonomous Cost efficient Energy Source and Storage (FACESS), involves the development of roll-to-roll printed organic photovoltaics and energy storage...
We present a new concept for a humidity sensor based on doped poly(aniline) that shows irreversible changes of its sheet resistance and capacitance upon exposure to humid conditions, i.e. a humidity memory. Therein humidity triggers an irreversible dedoping process, which results in a phase separation and crystallization of the hydrated form of its...
Various conducting polymers form a special class of materials with the potential for many applications in organic electronics and functional materials. These polymers can be electronically conducting or semiconducting due to a conjugated polymer backbone, or alternatively possess conductivity due to mobile protons or other ions. This thesis discuss...
Previously, localized conducting filaments have been suggested to explain the memory effects in metal–polymer–metal stacks, and nanoparticles and fullerenes have been dispersed in polymers to promote filament electroformation under the local electric fields modified by them. Therein, however, the aggregation tendency of the dispersed additives can...
In this patent and literary survey bioactive papers and fibre products, i.e. paper-like products, cardboard, fabrics and their combinations, etc., with active recognition and/or functional material capabilities are reviewed. The focus is on materials that specifically react with the target entity or environmental condition, and this reaction initia...
We report self-assembly and electronic conductivity transitions in polyaniline (PANI) where the iminic nitrogens are protonated by sulfonic acid-terminated low molecular weight poly(ethylene oxide) CH3−(O−C2H4−)46−CH2−SO3H (PEOSA), i.e., which contains 46 ethylene oxide repeat units. The complex PANI(PEOSA)0.5 self-assembles due to the comb-shaped...
High speed reel-to-reel manufacturing of electrically conductive polyaniline-dodecylbenzenesulfonic acid (PANI-DBSA) patterns directly onto paper substrate were investigated. A printing speed upto 100 meters per minute and line width down to 60 mum with a 60 cm wide paper web with a industrial scale pilot gravure printer was demonstrated. Additiona...
Future organic electronic and nanoelectronic applications will need organic memories as the devices and circuits get more complex. However, until very recently there has been limited research on the subject. Recent discoveries allow organic bistable devices to be used for nonvolatile memory applications [1]. We present a memory device concept that...