Search query: Flexible electronic film gel

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abstract: The increasing interest in flexible electronics and flexible displays raises questions regarding the inherent mechanical properties of the electronic materials used. Here, the mechanical behavior of thin film transistors used in active matrix displays is considered. The change of electrical performance of thin film semiconductor materials under mechanical stress is studied, including amorphous oxide semiconductors. This study comprises an experimental part, in which transistor structures are characterized under different mechanical loads, as well as a theoretical part, in which the changes in energy band structures in the presence of stress and strain are investigated. The performance of amorphous oxide semiconductors are compared to reported results on organic semiconductors and covalent semiconductors, i.e. amorphous silicon and polysilicon. In order to compare the semiconductor materials, it is required to include the influence of the other transistor layers on the strain profile. The bending limits are investigated, and shown to be due to failures in the gate dielectric and/or the contacts. Design rules are proposed to minimize strain in transistor stacks and in transistor arrays. Finally, an overview of the present and future applications of flexible thin film transistors is given, and the suitability of the different material classes for those applications is assessed.
author_names: Paul Heremans

Ashutosh Tripathi

A de Jamblinne de Meux

Edsger C P Smits

Bo Hou

Geoffrey Pourtois

Gerwin H Gelinck
title: Mechanical and Electronic Properties of Thin Film Transistors on Plastic, and Their Integration in Flexible Electronic Applications.
venue: Advanced materials
year: 2016

abstract: Abstract Flexible supercapacitors have drawn tremendous attention resulting from the rapid development of wearable electronic devices. Herein, we develop an effective and facile two step approach to prepare high content nitrogen, sulfur co doped porous carbon nanofibers film as electrodes of flexible supercapacitors. Benefiting from the high specific surface area and rich nitrogen/sulfur content, nitrogen and sulfur co doped porous carbon fibers film (N, S co doped PCFF) electrodes exhibit a high mass specific capacitance of 307.8 F g 1, and the capacitance retains 98% of initial capacitance after 5000 cycles in a three electrode system. The as assembled flexible supercapacitor devices with polyvinyl alcohol/KOH gel electrolyte demonstrate a highest mass specific capacitance of single electrode of 183.9 F g 1 at the scan rate of 2 mV s 1, which is better than that of other heteroatom doping carbon materials. In addition, the energy density reaches as high as 16.35 Wh kg 1 with the power density of 147 W kg 1 and retains as 5.34 Wh kg 1 with higher power density of 2402 W kg 1. Furthermore, the flexible devices show good cycling stability, superior flexibility and stable electrochemical performance.
author_names: Lina Chen

Weipeng Wang

Qing Ai

Guangmei Hou

Yanhui Li

Jun Lou

Lijie Ci
title: Nitrogen and sulfur co doped porous carbon fibers film for flexible symmetric all solid state supercapacitors
year: 2020

abstract: To satisfy the demands of wireless communication systems for tunable shielding materials, in this work, a graphene/ion gel/graphene sandwich structure is proposed, based on graphene and a solid ionic material ion gel. After modelling, preparing and testing, it was found that the structure could achieve more than 10 dB shielding effectiveness tuning in GHz and THz bands. Meanwhile, the adjusting speed of the structure was also studied, displaying effective dynamic tuning in the second order. Furthermore, the fabricated samples have the advantages of a low profile, easily conformable, and convenient processing, which are of great potential in emerging electronic devices.
author_names: Kui Wen

Yanli Xu

Jibin Liu

Peiguo Liu
title: Demonstration of Tunable Shielding Effectiveness in GHz and THz Bands for Flexible Graphene/Ion Gel/Graphene Film
year: 2021

abstract: In addition to the potential for memristors to be used in logic, memory, smart interconnects, and biologically inspired architectures that could transform traditional silicon based computing, memristors may enable such transformative technologies on physically flexible substrates. The simple structure of a memristor, which generally consists of a thin film of oxide sandwiched between two metal contacts, contributes to its compatibility with existing and future large area flexible electronics. This is especially true considering that recent work has demonstrated the ability for titanium dioxide based memristors to be deposited from solution at room temperature by using a sol gel technique on a flexible polymer substrate. The integration of memristors with traditional flexible devices (such as thin film organic, zinc oxide, or amorphous Si transistors) may enable the realization of a new paradigm in computing technology through lightweight, inexpensive, flexible electronics.
author_names: Nadine Gergel-Hackett

Joseph L Tedesco

Curt A Richter
title: Memristors With Flexible Electronic Applications
venue: Proceedings of the IEEE
year: 2012

abstract: Abstract As a functional ferroelectric material, PbZr0.53Ti0.47O3 (PZT) film is widely used in many electronic devices. However, with the rapid development of intelligent terminal, traditional PZT device cannot meet the demand for flexible wearable devices. In this work, a high quality flexible PZT film is fabricated by the controlled spalling technology (CST) for the first time, which is novel, simple and cost efficient. LaNiO3 (LNO) film by sol gel process is used as the buffer layer for the PZT film growth due to good lattice match and low cost. The PZT film on silicon substrate is successfully transferred onto a flexible one by electroplating Ni stressor layer. LNO buffer layer thickness has an important influence on the spalled silicon depth and Ni stressor layer thickness during the spalling process. The exfoliated PZT film based on sandwich capacitor structure Au/PZT/Au with an area of 1 cm2 exhibits good ferroelectric properties under different mechanical deformation. Moreover, the ferroelectric response of flexible PZT film does not show obvious deterioration after repeated operation cycles. Therefore, the flexible PZT thin film has a good application prospect on wearable ferroelectric microelectronics.
author_names: Jialu Zhang

Wei Jia

Qicheng Zhang

Jian He

Xushi Niu

Xiaojun Qiao

Wenping Geng

Xiaojuan Hou

Jundong Cho

Xiujian Chou
title: Controlled spalling and flexible integration of PZT film based on LaNiO3 buffer layer
venue: Ceramics International
year: 2019

abstract: There is an increasing demand for safe, environmentally benign energy storage devices in portable electronic appliances, wearable gadgets, flexible displays, and other personal multimedia devices. In this study, we have fabricated an all solid state flexible asymmetric supercapacitor using a novel 3D porous reduced graphene oxide/manganese dioxide@polyaniline (RGO/MnO2@PANI) hybrid film as the positive electrode and a self assembled 3D pillared graphene aerogel as the negative electrode material with a polyvinyl alcohol/potassium hydroxide (PVA/KOH) gel electrolyte. The flexible composite film was synthesized by vacuum filtration of GO and a MnO2@PANI mixture followed by chemical reduction of the resulting film in a hydrothermal autoclave. The 3D graphene aerogel was synthesized by a hydrothermal route using a solution of the nonionic triblock copolymer Pluronic F 68 as a soft template and vitamin C as a reducing agent. Herein, the Pluronic copolymer played dual roles: first, it enabled the effective dispersion of graphene oxide in water, and second, it assisted the formation of a stable 3D pillared hydrogel assembly. The RGO/MnO2@PANI based symmetric supercapacitor shows a high energy density of 18.33 W h kg 1 at a power density of 0.388 kW kg 1. An asymmetric supercapacitor (graphene aerogel//RGO/MnO2@PANI) which was fabricated by optimizing the individual electrode materials, exhibited a very high energy density of 38.12 W h kg 1 at a power density of 1.191 kW kg 1 utilizing a large potential window of 1.5 V. Moreover, 3 cells connected in series successfully lit up a red LED for 45 s and displayed similar performance under bending conditions.
author_names: Kalyan Ghosh

Chee Yoon Yue

Moniruzzaman Sk

Rajeeb Kumar Jena

Shuguang Bi
title: Development of a 3D graphene aerogel and 3D porous graphene/MnO2@polyaniline hybrid film for all solid state flexible asymmetric supercapacitors
year: 2018

abstract: Printed circuit boards are a platform technology for virtually all electronic devices. Conventional rigid and flexible circuit materials based on copper clad thermoset polymers have served the industry well for many decades. New generations of electronics require circuit boards (or more accurately, membranes) that are pliable, conformable and even stretchable. Thermoplastic based films and conductive pastes are commonly used to form these structures today, but their mechanical and electrical durability limitations are well known. The researchers fashioned a new, first of its kind, stretchable circuit construction by combining a non silicone thermosetting film with inorganic eutectic Gallium Indium Tin metal gel to form a functional multilayer circuit complete with passive surface mount components. This paper describes the materials, fabrication and testing of this unique construction.
author_names: Mark Ronay

Trevor Rivera

Mike Hopkins

Chuck Kinzel

Sydney Bright

Andy Behr

Takatoshi Abe

Tomohiro Fukao

Tomoaki Sawada

Kyosuke Michigami
title: Construction and Testing of a Functional Multilayer Demonstration Circuit Made with Gallium Indium Tin Metal Gel and Non Silicone Stretchable Thermosetting Film
venue: 2019 IEEE International Flexible Electronics Technology Conference (IFETC)
year: 2019

abstract: Abstract Development of successful flexible electronic devices desires excellent compliancy between the deposited inorganic thin film materials and flexible polymeric substrates as the film substrate assembly is conformally mounted over uneven surfaces. Several physical parameters control the optimal surface science at the metal polymer interface and result in the formation of either continuously buckled thin film structures or electrically discontinuous cracked films. Buckling of thin film materials has always been observed when deposited over soft complaint substrate material either through physical techniques like sputtering or thermal evaporation or through chemical solution processing techniques like sol gel, chemical bath deposition, electrodeposition, chemical vapor deposition, and spray pyrolysis. However, successful utilization of these buckles in flexible or stretchable electronic application requires excellent compliancy between the two without any cracking during its fabrication or flexibility operation. This chapter discusses in details the challenges faced in meeting these compliancy issues when nichrome thin film is physically deposited over soft viscoelastic polymer materials like polydimethylsiloxane, namely, crack formation, optimal deposition parameters, buckling induced flexibility, nonplanar topologies for buckle orientation and stability, and its limitations. Prestretching technique of elastomeric substrates was employed thereafter to induce large buckles after successfully fabricating flexible devices over the stretched surface using novel photolithography technique. Finally, applicability of the large buckles in aiding greater device flexibility was also highlighted through a prototype fabrication of a catheter mounted flexible flow sensor to monitor abnormalities in blood flow velocities near stenotic arteries. These research findings thus successfully address issues related to the feasibility of cost effective flexible microsensors for various biomedical applications.
author_names: Debashis Maji

Soumen Das
title: Buckling assisted thin film deposition and lithographic strategies for flexible device patterning
year: 2021

abstract: Abstract The development of portable and wearable electronic devices continues to increase the demand for miniature energy storage units. Here, we fabricate the flexible micro supercapacitors (MSCs) through direct heating pattern on graphene oxide film. The shape designable MSCs are based on planar reduced graphene oxide/graphene oxide (rGO/GO) structure, with rGO as electrode and GO as separator. The GO area heated by heating pen is reduced to rGO, and the area with no heating is still GO. The interdigitated MSC made at 400 degC delivers high area capacitance of 94.8 mF cm 2 at current density of 0.25 mA cm 2 within poly(vinyl alcohol) (PVA)/H2SO4 gel electrolyte. It provides high energy density of 10.7 mWh cm 2 at power density of 112.6 mW cm 2. In addition, it also has excellent mechanical stability, with basically unchanged area capacitance from 0deg to 180deg bending angles. The MSCs with shapes of spiral, concentric circle and eight trigrams are also fabricated via this method. The results indicate that heating pattern on GO films to build flexible MSC is a promising and low cost new method to fabricate energy storage equipment for future electronic devices.
author_names: Cheng-Hao Peng

L Niu

Hong Yuan

Jiahui Xu

Yuanjun Yang

Guoxiang Li
title: Direct heating pattern on graphene oxide film to build flexible micro supercapacitors
year: 2021

abstract: Abstract The immense potential of photo electrical materials applied in intelligent and wearable electronic devices has motivated many researches on flexible ferroelectric thin film. However, how to enhance stability of output and achieve multifunction is still a challenge. Here, an all inorganic flexible ferroelectric thin film with Au/Bi2FeMo0.7Ni0.3O6/LaNiO3/Nickel foil structure is prepared by sol gel method. The thin film exhibits excellent photovoltaic stability. The change rates of the short circuit currents and open circuit voltages are less than 5% in different bending states and after bending releasing cycles, which is attributed to its stable self polarization characteristic. Furthermore, an optically tunable resistive switching behavior is found in the thin film. The switching voltages and ON/OFF ratio of resistance can be tuned in real time by on off control of light, demonstrating a correlation between resistive switching and photovoltaic effect. It is proposed that the photovoltaic effect modulates the energy band structure of the thin film, leading to an increased ON/OFF ratio of resistance. This work opens up a promising route to the development of multifunctional flexible photo electrical materials.
title: Stable photovoltaic output and optically tunable resistive switching in all inorganic flexible ferroelectric thin film with self polarization characteristic
year: 2021