https://orbit.dtu.dk/files/7590153/Roll_to_roll_fabrication.pdf

Roll-to-roll fabrication of polymer solar cells

The cost-effective production of flexible electronic components will profit considerably from the development of solution-processable, organic semiconductor materials. Particular attention is focused on soluble semiconductors for organic field-effect transistors (OFETs). The hitherto differentiation between "small molecules" and polymeric materials no longer plays a role, rather more the ability to process materials from solution to homogeneous semiconducting films with optimal electronic properties (high charge-carrier mobility, low threshold voltage, high on/off ratio) is pivotal. Key classes of materials for this purpose are soluble oligoacenes, soluble oligo- and polythiophenes and their respective copolymers, and oligo- and polytriarylamines. In this context, micro- or nanocrystalline materials have the general advantage of somewhat higher charge-carrier mobilities, which, however, could be offset in the case of amorphous, glassy materials by simpler and more reproducible processing.

Organic semiconductors for solution-processable field-effect transistors (OFETs).

With the arising of global climate change and resource shortage, in recent years, increased attention has been paid to environmentally friendly materials. Trees are sustainable and renewable materials, which give us shelter and oxygen and remove carbon dioxide from the atmosphere. Trees are a primary resource that human society depends upon every day, for example, homes, heating, furniture, and aircraft. Wood from trees gives us paper, cardboard, and medical supplies, thus impacting our homes, school, work, and play. All of the above-mentioned applications have been well developed over the past thousands of years. However, trees and wood have much more to offer us as advanced materials, impacting emerging high-tech fields, such as bioengineering, flexible electronics, and clean energy. Wood naturally has a hierarchical structure, composed of well-oriented microfibers and tracheids for water, ion, and oxygen transportation during metabolism. At higher magnification, the walls of fiber cells have an interes...

https://www.fpl.fs.fed.us/documnts/pdf2016/fpl_2016_zhu001.pdf

Wood-Derived Materials for Green Electronics, Biological Devices, and Energy Applications.

Printing sensors and electronics over flexible substrates are an area of significant interest due to low-cost fabrication and possibility of obtaining multifunctional electronics over large areas. Over the years, a number of printing technologies have been developed to pattern a wide range of electronic materials on diverse substrates. As further expansion of printed technologies is expected in future for sensors and electronics, it is opportune to review the common features, the complementarities, and the challenges associated with various printing technologies. This paper presents a comprehensive review of various printing technologies, commonly used substrates and electronic materials. Various solution/dry printing and contact/noncontact printing technologies have been assessed on the basis of technological, materials, and process-related developments in the field. Critical challenges in various printing techniques and potential research directions have been highlighted. Possibilities of merging various printing methodologies have been explored to extend the lab developed standalone systems to high-speed roll-to-roll production lines for system level integration.

https://cris.fbk.eu/bitstream/11582/300858/1/Technologies%20for%20Printing%20Sensors%20and%20Electronics%20Over%20Large%20Flexible%20Substrates-A%20Review.pdf

Technologies for Printing Sensors and Electronics Over Large Flexible Substrates: A Review

With the prospect of extremely fast manufacture of very low cost devices, organic electronics prepared by thin film processing techniques that are compatible with roll-to-roll (R2R) methods are presently receiving an increasing interest. Several technologies using organic thin films are at the point, where transfer from the laboratory to a more production-oriented environment is within reach. In this review, we aim at giving an overview of some of the R2R-compatible techniques that can be used in such a transfer, as well the current status of R2R application within some of the existing research fields such as organic photovoltaics, organic thin film transistors, light-emitting diodes, polymer electrolyte membrane fuel cells, and electrochromic devices. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012

https://onlinelibrary.wiley.com/doi/pdf/10.1002/polb.23192

Roll‐to‐Roll fabrication of large area functional organic materials

Printed Paper Photovoltaic Cells

Organic field-effect transistors were fabricated using offset printed source/drain structures. Interdigitated electrode structures were printed with a poly(3,4–ethylenedioxythiophene) (PEDOT) formulation. A polymeric semiconductor polytriarylamine and different insulator layers were deposited by spin coating. A field-effect mobility of 3×10−3cm2V−1s−1 and on/off ratio of about 103 was achieved, making it possible to produce digital logic elements.

Polymer-based organic field-effect transistor using offset printed source/drain structures

In this paper, a low cost and flexible plantar pressure monitoring system is presented that is suited for everyday use to prevent pressure ulcers. To define the technical specifications of the sensor system, a gait analysis study was carried out. Analysis of measured data based on a multivariate approach and neural network classification shows that it is possible to dissociate between healthy and unhealthy rollover patterns. To implement a pressure sensor element, a multiwalled carbon nanotube (MWCNT)-polydimethylsiloxane (PDMS)-composite was selected. A sensor matrix made of the composite was fully printed to enable pressure distribution measurements. As a final application, a printed insole was fabricated with six single MWCNT-PDMS pressure sensors that were situated on characteristic points of the insole to detect the unhealthy rollover patterns. Its functionality to measure plantar pressures was proven on a human foot inside a running shoe during walking.

Printed MWCNT-PDMS-Composite Pressure Sensor System for Plantar Pressure Monitoring in Ulcer Prevention

Fully mass-printed organic field-effect transistors were made completely by means of gravure printing. Therefore a special printing layout was developed in order to avoid register problems in print direction. Upon using this layout, contact pads for source–drain electrodes of the transistors are printed together with the gate electrodes in one and the same printing run. More than 50,000 transistors have been produced and by random tests a yield of approximately 75% has been determined. The principle suitability of the gravure printed transistors for integrated circuits has been shown by the realization of ring oscillators.

Uniformity of fully gravure printed organic field-effect transistors

A complementary ring oscillator has been prepared using exclusively fast and continuous rotary printing methods, namely, gravure and flexographic printing, so that all layers were additively deposited and no additional patterning nor interconnecting step whatsoever was involved. This became possible due to the availability of a printable air-stable n-type organic semiconductor, i.e., a small molecule perylene derivative. Using the same dielectric for both types of transistors, the characteristics of the n-type transistors are reasonably similar to the ones of the p-type transistors, which are based on the previously used organic semiconductor 6,13-bis(triisopropylsilylethynyl) pentacene. The printed circuits are robust against variations of individual transistor parameters and significantly outperform comparable unipolar circuits in terms of all relevant properties. The superior performance can be attributed to complementary circuitry, the advantage of which is thereby demonstrated for the case of printed circuits.

Arved C. Hübler

Papers

Printed Paper Photovoltaic Cells

Polymer-based organic field-effect transistor using offset printed source/drain structures

Printed MWCNT-PDMS-Composite Pressure Sensor System for Plantar Pressure Monitoring in Ulcer Prevention

Uniformity of fully gravure printed organic field-effect transistors

Complementary Ring Oscillator Exclusively Prepared by Means of Gravure and Flexographic Printing