Organic Electronic Systems Research Articles

A complete compact model for simulation of organic electronic systems

Organic Electronics provides multiple technological advantages such as low cost, flexibility, solution processability and waste reduction through the use of new materials and alternative fabrication techniques in the microelectronic world. The use of additive and printed fabrication processes allows the development of instantly fabricated, fully additive, low temperature processing together with lightweight, bendable, scalable and sustainable systems. Different models have been presented in the field but none of them with an industrial implementation. Complete simulation models are very useful for circuit production and commercialization since the organic electronics market is expected to grow in the near future and the need for industrial solutions for designers will increase. For this reason and for the first time, we present a compact model of DC and AC behaviour combined with different ambient conditions and parameter variability for full organic electronic system simulations.

Cumulene-like bridged indeno[1,2-b]fluorene π-conjugated polymers synthesized on metal surfaces.

Among the plethora of polycyclic structures that have emerged in recent years, indenofluorenes comprise a unique class of compounds due to their potential in organic electronic systems such as OLEDs, OFETs, and OPVCs. However, the synthesis of fully conjugated indenofluorenes without bulky groups on the apical carbons under standard chemistry conditions is not easily accessible. In this regard, on-surface synthesis has appeared as a newly developing field of research, which exploits the use of well-defined solid surfaces as confinement templates to initiate and develop chemical reactions. Here, we demonstrate the successful fabrication of indeno[1,2-b]fluorene π-conjugated polymers linked via cumulene-like connections on well-defined metallic surfaces under ultra-high vacuum conditions. The structure and electronic properties of the formed polymers have been precisely characterized by scanning tunneling microscopy, noncontact atomic force microscopy and scanning tunneling spectroscopy, complemented by computational investigations.

Enhancement of Thermal Boundary Conductance of Metal-Polymer System.

In organic electronics, thermal management is a challenge, as most organic materials conduct heat poorly. As these devices become smaller, thermal transport is increasingly limited by organic–inorganic interfaces, for example that between a metal and a polymer. However, the mechanisms of heat transport at these interfaces are not well understood. In this work, we compare three types of metal–polymer interfaces. Polymethyl methacrylate (PMMA) films of different thicknesses (1–15 nm) were spin-coated on silicon substrates and covered with an 80 nm gold film either directly, or over an interface layer of 2 nm of an adhesion promoting metal—either titanium or nickel. We use the frequency-domain thermoreflectance (FDTR) technique to measure the effective thermal conductivity of the polymer film and then extract the metal–polymer thermal boundary conductance (TBC) with a thermal resistance circuit model. We found that the titanium layer increased the TBC by a factor of 2, from 59 × 106 W·m−2·K−1 to 115 × 106 W·m−2·K−1, while the nickel layer increased TBC to 139 × 106 W·m−2·K−1. These results shed light on possible strategies to improve heat transport in organic electronic systems.

All‐Solid‐State Organic Schmitt Trigger Implemented by Twin Two‐in‐One Ferroelectric Memory Transistors

AbstractAlthough there have been many attempts to replace conventional inorganic electronics with organic materials that can be mass produced at low cost, few organic electronic filters to increase immunity to electrical noise have been reported thus far. Conventional Schmitt triggers or their inverters are used in many electronic circuits as versatile electronic noise filters. However, it is challenging to manufacture organic electronic systems with complex circuitry. In this study, a simple, all‐solid‐state organic Schmitt trigger consisting of twin two‐in‐one organic ferroelectric memory transistors with the same chemical compositions and device dimensions but different threshold voltages is introduced. Threshold voltages and hysteresis in the two‐in‐one devices can be controlled by polarization switching as demonstrated in a previous study. Hysteresis of a ferroelectric p‐type depletion load inverter can be achieved using twin two‐in‐one devices when the sweep voltage is higher than the critical gate voltages. This facilitates inverter characteristics at two different threshold voltages, and realizing a Schmitt trigger. Finally, based on simulation program with integrated circuit emphasis (SPICE) simulation, guidelines are proposed on how to design organic Schmitt triggers with p‐ or n‐type materials and ferroelectric or charge‐trapping mechanisms to achieve inverting or non‐inverting characteristics.

Review on flexible photonics/electronics integrated devices and fabrication strategy

In recent years, to meet the greater demand for next generation electronic devices that are transplantable, lightweight and portable, flexible and large-scale integrated electronics attract much more attention have been of interest in both industry and academia. Organic electronics and stretchable inorganic electronics are the two major branches of flexible electronics. With the semiconductive and flexible properties of the organic semiconductor materials, flexible organic electronics have become a mainstay of our technology. Compared to organic electronics, stretchable and flexible inorganic electronics are fabricated via mechanical design with inorganic electronic components on flexible substrates, which have stretchability and flexibility to enable very large deformations without degradation of performance. This review summarizes the recent progress on fabrication strategies, such as hydrodynamic organic nanowire printing and inkjet-assisted nanotransfer printing of flexible organic electronics, and screen printing, soft lithography and transfer printing of flexible inorganic electronics. In addition, this review considers large-scale organic and inorganic flexible electronic systems and the future applications of flexible and stretchable electronics.

Roll-to-roll processing of film substrates for hybrid integrated flexible electronics

Roll-to-roll (R2R) processing on film substrates has been demonstrated to have the potential for achieving high throughput manufacturing of organic electronic systems at low cost. However, the ever-growing mobile devices market accompanied by the developments in information and communication technologies require high performance systems at very low power operation, sometimes on larger substrates having sizes in the range of a few metres. Organic electronics often fall short of fulfilling the required computing performance and power requirements of most of the common use cases. Hybrid integration of inorganic monocrystalline silicon chips on polymer films is a means to fulfil the aforementioned requirements. In this context, it is opportune to report our recent activities on R2R processing of plastic films for hybrid integration of flexible electronics. Hybrid integration can be performed with conventional, rigid surface mount devices as well as flexible, ultra-thin bare silicon chips. The first section of the paper is dedicated to a brief overview of R2R manufacturing of electronic devices with an example of production of radio frequency identification tags as well as to a discussion emphasising the targets for hybrid integration. Then, detailed descriptions about our processes for R2R manufacturing of metal wiring lines on films and hybrid integration are included. Three-dimensional integration of films and a temperature sensor label manufactured using hybrid integration process are also elaborated on. Furthermore, key results from fatigue reliability assessment of R2R metallised wiring lines are reported. Finally, some of the challenges in transferring the R2R processes for hybrid integration on film substrates from research labs to industrial manufacturing are highlighted.

Array of Organic Field-Effect Transistor for Advanced Sensing

Organic electronics, taking advantage of flexibility and environmental sensitivity, have been investigated for diverse applications including flexible displays, wearable electronic devices and solar cells. A compelling additional application of organic electronics is sensing, especially of chemicals, pressure and light. As the key materials of organic electronics, organic semiconductors have been intensively studied, and have achieved mobility and stability good enough to be applied in various electronic circuits and systems with moderate complexity. This article presents a brief review of the transistor array systems, focusing on using arrays of organic field-effect transistors (OFETs) for advanced sensing applications. OFET-based sensors are able to transduce an environment changing event into an electric signal by utilizing the unique combination of electric and environmental sensitive properties of organic semiconductors. Additionally, designing the microstructure and introducing the interfacial interaction inside the OFETs are another approaches to provide increased sensing capability to the devices. By incorporating the OFET sensors into arrays, advanced sensing can be further realized, such as tactile sensing, pattern imaging, skin-like temperature detecting and electronic nose. It is expected that by reviewing these OFET sensor arrays, this article could provide an inspiration for advanced applications based on organic electronic circuits and systems.

11.2: Invited Paper: Imperceptible Electronic Skin

AbstractWe present the fabrication and electrical and mechanical characteristics of a 1‐μm‐thick ultraflexible organic transistor and demonstrate the imperceptible organic electronic systems for “Electronic Skins.” Ultraflexible and lightweight electronics, e.g., organic solar cells, polymer light‐emitting diodes and active matrix amplifiers, are manufactured on 1‐μm‐thick plastic substrates

Elucidating the nanoscale origins of organic electronic function by conductive atomic force microscopy

Electronic and optoelectronic devices comprising organic materials are highly promising for mechanically flexible and low-cost applications. In recent years, conductive atomic force microscopy (C-AFM) has played a significant part in deciphering the nanoscopic and mesoscopic origins of organic electronic function. C-AFM is uniquely capable of measuring local electrical properties with nanoscale resolution; moreover, in conjunction with complementary atomic force microscope modes, C-AFM enables simultaneous mapping of nanoscale structure and electrical function. This feature article highlights recent progress in applying C-AFM to characterize organic electronic systems including self-assembled monolayers, graphene and related materials, organic semiconductors, and organic photovoltaic heterojunctions.

Fast-switching all-printed organic electrochemical transistors

Symmetric and fast (∼5ms) on-to-off and off-to-on drain current switching characteristics have been obtained in screen printed organic electrochemical transistors (OECTs) including PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonic acid)) as the active transistor channel material. Improvement of the drain current switching characteristics is made possible by including a carbon conductor layer on top of PEDOT:PSS at the drain electrode that is in direct contact with both the channel and the electrolyte of the OECT. This carbon conductor layer suppresses the effects from a reduction front that is generated in these PEDOT:PSS-based OECTs. In the off-state of these devices this reduction front slowly migrate laterally into the PEDOT:PSS drain electrode, which make off-to-on switching slow. The OECT including carbon electrodes was manufactured using only standard printing process steps and may pave the way for fully integrated organic electronic systems that operate at low voltages for applications such as logic circuits, sensors and active matrix addressed displays.

Energy transfer from conjugated polymer to bacterial light-harvesting complex

Energy transfer from a conjugated polymer blend (poly(9,9-dioctylfluorenyl-2,7-diyl):poly (2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene) to a light-harvesting complex 2 from purple bacteria has been demonstrated using time-resolved fluorescence spectroscopy. For our hybrid nanostructure, we observe a 30% reduction of the fluorescence lifetime of the polymer emission as compared to the pure polymer layer. This result is an important step towards integrating naturally evolved biomolecules with synthetic materials into biohybrid organic electronic systems.

Impurity-related vibrational modes in a pentacene crystal

The presence of impurities in the molecular crystals of organic semiconductors is a key limiting factor for the performance of related electronic devices. For this reason, the atomic-scale details of impurity incorporation are important elements for modeling and optimization of organic electronic systems. In this article, we use first-principles density-functional theory calculations to describe the vibrational spectrum of typical impurity culprits in the prototype organic semiconductor pentacene. First, we validate the computational approach by comparing results on vibrational modes of impurity-free pentacene with available theoretical and experimental data. We then analyze the effect of oxygen, water, and hydrogen impurities on the modes of pentacene crystals. The results identify distinct impurity-related features which can help understand the evolution of impurities in pentacene samples.

Nanoimprint of ordered ferro/piezoelectric P(VDF-TrFE) nanostructures

The next generation of portable computing and communication devices tremendously depend on the technologies that enable the rapid manipulation, caching and high-density non-volatile data storage. The recent development of organic electronics requires high-quality organic memory compatible with other devices, which will eventually lead to the realization of all organic electronic systems. The challenge of the organic electronics application is to find less degradative ways of fabricating ferroelectric polymer nanostructures. In this work, we applied the nanoimprint technique to fabricate ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer line and dot nanostructures and compared the ferroelectric properties and domain formation in these two nanostructures.

Blue phosphorescent organic light-emitting devices utilizing cesium–carbonate-doped 2,4,6-tris(2′,4′-difluoro-[1,1′-biphenyl]-4-yl)-1,3,5-triazine

We report an alternative, high-yielding synthesis for the known compound 2,4,6-tris(2′,4′-difluoro-[1,1′-biphenyl]-4-yl)-1,3,5-triazine (tris-(dFB)Tz). The energy of the lowest unoccupied molecular orbital (ELUMO) for tris-(dFB)Tz is estimated to be −3.5 eV from electrochemical measurements. The deep ELUMO of tris-(dFB)Tz affords a material with excellent electron acceptor characteristics for use in n-doped electron transport layers. Tris-(dFB)Tz shows a four order of magnitude increase in the number of carriers on doping with 8 wt. % Cs2CO3. Enhanced electron injection was also observed on doping with Cs2CO3, which eliminated the necessity for a separate LiF electron injection layer. Blue phosphorescent organic light-emitting devices (OLEDs) were fabricated using n-doped tris-(dFB)Tz electron transport layers. OLEDs with thick (700-A) Cs2CO3-doped tris-(dFB)Tz electron transport layers had lower operating voltages than OLEDS with an undoped electron transport layer of bis(diphenylphosphoryl)dibenzothiophene (PO15), which has previously been used in low-voltage, high-efficiency OLEDs. The tris-(dFB)Tz results indicate that aromatic substituted triazines may be promising materials for use as electron acceptors in n-doped organic electronic systems.

Micro‐ and Nanopatterning Techniques for Organic Electronic and Optoelectronic Systems

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Micro- and Nanopatterning Techniques for Organic Electronic and Optoelectronic Systems

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMicro- and Nanopatterning Techniques for Organic Electronic and Optoelectronic SystemsEtienne Menard, Matthew A. Meitl, Yugang Sun, Jang-Ung Park, Daniel Jay-Lee Shir, Yun-Suk Nam, Seokwoo Jeon, and John A. RogersView Author Information Department of Materials Science and Engineering, Department of Chemistry, Beckman Institute, and F. Seitz Materials Research Laboratory, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801; and Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 Cite this: Chem. Rev. 2007, 107, 4, 1117–1160Publication Date (Web):April 11, 2007Publication History Received3 August 2006Published online11 April 2007Published inissue 1 April 2007https://doi.org/10.1021/cr050139yCopyright © 2007 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views11852Altmetric-Citations570LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (4 MB) Get e-AlertsSUBJECTS:Electrodes,Layers,Materials,Polymers,Transistors Get e-Alerts

Large Area Printing of Organic Electronics

Organic electronic systems offer the possibility of lightweight, flexibility and large area coverage, properties not easily achievable with standard silicon technology, and at potentially lower manufacturing costs. DuPont has focused on the development of conducting and semiconducting organic materials that allow for the printing of active and passive electronic devices. A number of groups have focus in improving device performance by designing organic semiconducting materials of higher mobility. We demonstrate an alternative path for achieving high transconductance organic transistors in spite of relatively large source to drain distances. The method, based on creating subpercolating conducting networks, would enable the printing of submicron features with conventional commercial engines. The improvement of the electronic characteristic of such a scheme is equivalent to a 60-fold increase in effective mobility without reduction of the on/off ratio.These conducting and semiconducting composites are compatible with various large area printing processes such as thermal and ink jet. However, the manufacturing of complex multi-layer circuits over large areas in a reel-to-reel configuration has been one of the driving forces in the organic electronics field. We are currently evaluating the feasibility of micro-contact printing as a path to high-resolution reel-to-reel electronics. Thus extending flexography into the high-resolution arena. Unlike conventional lithography, micro-contact printing; not requiring sacrificial resists, developers, and etchants; maybe compatible with a wider range of materials and substrates currently utilized in plastic electronics.

Large Area Printing of Organic Transistors via a High Throughput Dry Process

Organic electronic systems offer the advantage of low weight and flexibility at potentially lower cost. Although the fabrication of functioning plastic transistors using approaches such as ink jet, lithography and stamping has been described i1–3, chemically compatible materials that allow for the sequential application of liquid layers is a technical barrier. Material issues maybe the Achilles heel of ultimately printing organic electronic devices as newspapers today, at high speeds and in a reel to reel process. We introduce a novel process–thermal transfer–a non-lithographic technique that enables printing multiple, successive layers via a dry additive process. This method is capable of patterning a range of organic materials at high speed over large areas with micron size resolution and excellent electrical performance. Such a dry, potentially reel-to-reel printing method may provide a practical route to realizing the expected benefits of plastics for electronics. We illustrate the viability of thermal transfer and the ability to develop suitable printable organics conductors by fabricating a functioning 4000 cm2 transistor array.