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Flexible and Stretchable Thin-Film Transistors
Published in Muhammad Mustafa Hussain, Nazek El-Atab, Handbook of Flexible and Stretchable Electronics, 2019
Joseph B. Andrews, Jorge A. Cardenas, Aaron D. Franklin
Lastly, template-based roll-to-roll printing techniques have been shown to produce CNT thin-film devices at extremely high throughput [75]. While roll-to-roll printing techniques can be used to print the necessary complementary materials for CNT-TFT devices, there has been no work demonstrating the roll-to-roll printing of semiconducting CNTs. However, due to the compatibility with CNT thin films, and its prevalence in the field, this deposition technique must be mentioned. The method is similar to traditional newspaper printing, in which rolls are used to pick up patterned materials (through metal/hard material stencils) and in turn deposit the materials on the desired substrate. The main methods include knife-over-edge coating, slot-die coating, gravure printing, and screen printing [108]. The primary disadvantage to this technique is the low degree of control. Apart from the pattern designs and ink selection, the only print parameter capable of being adjusted is the roll speed. For research, roll-to-roll printing is especially unfavorable as a new, expensive mask must be manufactured each time a new design is to be printed. Additionally, there is a tight window of ink viscosities compatible with these techniques, which can restrict material selection and ink formulation, and ultimately is why s-CNT inks have not been printed using roll-to-roll techniques. The primary advantages that stem from roll-to-roll printing include throughput and, therefore, the capacity for low-cost large area electronic manufacturing. A device printed using roll-to-roll techniques is illustrated in Figure 4.6c. More information on printing technologies and their relation to flexible electronics can be found in Chapter 9.
Passive Biosensors for Flexible Hybrid-Printed Electronic Systems
Published in George K. Knopf, Amarjeet S. Bassi, Smart Biosensor Technology, 2018
Christian Fayomi, Herve Achigui Facpong, Gordon W. Roberts
The roll-to-roll manufacturing process provides high throughput and higher line pattern resolution over large substrate rolls. Fully additive and subtractive processes are often combined to achieve continuous production with well-controlled deposition, patterning, and packaging per final device requirements. R2R printing system configuration consists of a combination of deposition, gravure, offset, flexography, screen-printing, and nanoimprint technologies.
Polymer Semiconductors
Published in Inamuddin, Mohd Imran Ahamed, Rajender Boddula, Tariq Altalhi, Polymers in Energy Conversion and Storage, 2022
Moises Bustamante-Torres, Jocelyne Estrella-Nuñez, Odalys Torres, Sofía Abad-Sojos, Bryan Chiguano-Tapia, Emilio Bucio
Semiconductor polymers are the most promising functional polymers (Schenning and Meijer 2001), with a huge range of potential applications. Polymeric semiconductors promise a new paradigm in electronic device fabrication. The ability to utilize roll-to-roll processing or other existing printing technologies to produce large-area, flexible, and stretchable devices has the potential to reduce manufacturing costs drastically (McBride et al. 2018).
Control of roll-to-roll manufacturing based on sensorless tension estimation and disturbance compensation
Published in Journal of the Chinese Institute of Engineers, 2021
Pao-Yao Huang, Ming-Yang Cheng, Ke-Han Su, Wei-Liang Kuo
Recently, due to attractive features such as light weight as well as being thin, flexible and easy to store, flexible electronic products such as flexible E-papers, speakers and displays have received much attention. In particular, the flexible properties make flexible electronic products suitable for roll-to-roll manufacturing. It is well known that the roll-to-roll manufacturing process is capable of continuous production and handling various sizes of products. Compared with conventional manufacturing processes, the roll-to-roll manufacturing process has advantages in yield rate and production efficiency. As a result, developing core technologies of roll-to-roll manufacturing processes plays a crucial role in enhancing the competitiveness of the flexible electronics industry. To conduct an in-depth study on the control problems of roll-to-roll manufacturing processes, this paper focuses on the design of tension and transmission speed controllers.
A novel nematic tri-carbazole as a hole-transport material for solution-processed OLEDs
Published in Liquid Crystals, 2021
Guang Hu, Stuart P. Kitney, Muralidhar Reddy Billa, Stephen M. Kelly, Brian Lambert, William Harrison
Organic light-emitting diodes (OLEDs) have attracted widespread attention in recent years due to their potential application in flat panel-full colour display, solid-state lighting, as well as flexible and wearable electronics [1–3]. They emerged as a promising lighting technology because of their environment-friendly nature unlike power-consuming fluorescent lamps and incandescent bulbs that uses harmful mercury, which is hard to dispose [4]. OLEDs have great advantages such as flexibility, fast response, wide viewing angle, high contrast, high brightness, low power consumption, transparent, lightweight and wide operating temperature range [5–8]. The OLED structure consists of multiple layers, which includes the hole-transporting layer (HTL), electron-transporting layer (ETL) and emissive layer (EML) sandwiched between the transparent anode and cathode. Therefore, many efforts have been carried out to develop suitable hole-transport layer, as the hole-transport materials are very crucial for device performance by decreasing the energy barrier between anode and emissive layer as well as helps recombination of holes and electrons [9–11]. In general, the hole-transport material in organic semiconductor device should possess good hole mobility, thermal stability, appropriate LUMO levels to block the electrons from emissive layer to hole-transport layer and suitable HOMO levels to lowering the energy barrier for efficient hole injection from the anode into the emissive layer for recombination [12–14]. Moreover, traditional industrial OLED devices are manufactured by vapour deposition under vacuum and at high temperature in order to fabricate thin films. It can be much more expensive compared with wet-chemistry deposition of uniform thin films from solution. The latter techniques can be used in continuous manufacturing processes, such as roll-to-roll printing.
Engineering fibre morphology in self-assembled physical gels of a prototypical discotic liquid crystal
Published in Liquid Crystals, 2021
Qurat Ul Ain, Sehrish Iqbal, Shahzad Akhtar Ali, Murtaza Saleem, Habib Ur Rehman, Ata ulHaq, Ammar A. Khan
DSSCs are third generation solar cells, and the underlying photoelectrochemical device concept has been an area of intense study since the seminal articles published in 1991 [30]. In the last decade, DSSC research has largely transformed into the search for high efficiency and stable perovskite solar cells [31,32]. Commercialisation of DSSCs has been hindered due to stability issues caused by evaporation of the volatile liquid electrolyte (for which physical gel electrolytes are an excellent remedy), and generally lower power conversion efficiencies than current commercial solar cells. However, there are several reasons to continue developing more stable and efficient DSSCs. It has been shown that a combination of absorbing dyes can lead to panchromatic absorption with very high short-circuit currents [33], and the highest performing DSSCs have reported efficiencies up to 14.2% [34]. Furthermore, DSSCs can be made to be very stable using advanced sealing techniques, solid state hole transport layers [35], as well as using physical gel electrolytes [13] to mitigate solvent evaporation. They exhibit excellent low light device performance, making them useful in niche applications where inorganic technologies would have a competitive disadvantage. The bright colours and semitransparency have aesthetic advantages that can be readily tuned, and even serve as structural elements [36]. The technology is cheap, does not require expensive fabrication equipment for scalable roll-to-roll assembly, and non-toxic (depending on configuration). Finally, DSSCs provide a model working system that facilitates investigations into the underlying physics of light absorption, charge transport, catalysis and photovoltaics. We test triphenylene physical gels as electrolytes in DSSCs as a model electrochemical system and map changes in gel morphology to photovoltaic device performance. Furthermore, the effect of the addition of amphiphilic dye Z907 is investigated, to test our hypothesis that favourable interactions between the sensitiser and DLC gelators can help improve dielectric screening and lower parasitic recombination in DSSCs and similar electrochemical devices.