“…Moreover, VOFETs can be used to easily produce large-area ICs using printing techniques. This is usually considered as a problem in POFETbased ICs that usually contain less than 100 POFETs [214,[251][252][253][254][255][256] because of the low resolution and large feature size of most of the printing techniques. [257] Comparatively, the fabrication of POFETs on flexible substrates (both biorelevant and plastic) is a mature research area, with applications ranging from simple logic gates to unipolar and complementary ring oscillators.…”
Section: Discussion and Comparison Between Pofet-and Vofet-based Flex...mentioning
confidence: 99%
“…Moreover, VOFETs can be used to easily produce large‐area ICs using printing techniques. This is usually considered as a problem in POFET‐based ICs that usually contain less than 100 POFETs [ 214,251–256 ] because of the low resolution and large feature size of most of the printing techniques. [ 257 ]…”
“…[179] Although it shows great potential for low-temperature fabrication on flexible substrates and cost-effective large-area production, it is rarely used to manufacture printed organic ICs. The main challenge, in this context, is the absence of technology scaling, as most of the printed ICs contain less than 100 POFETs [214,[251][252][253][254][255][256] because of the low resolution and large feature size of most of the printing techniques. [257] Considering these limitations, Kwon et al demonstrated 3D monolithic integration of flexible printed POFETs to realize technology scaling.…”
Section: Application In Flexible Logic Gates Inverters and Oscillatorsmentioning
According to the forecast of Allied Market Research, the flexible electronics market is projected to reach $42.48 billion by 2027. It is estimated to revolutionize the lighting technology, power integration displays, and health monitoring systems. The popularity of flexible electronics is mainly due to the unique benefits of organic materials and devices that offer cost-effectiveness, low-temperature processability, mechanical softness, and shape adaptability, [5][6][7] which are difficult to obtain with traditional, complementary-metal-oxide-semiconductor (CMOS)-based rigid systems. [8] Over the past two decades, research interest in flexible electronic systems has grown exponentially, driven by the requirements of interface softness and shape adaptability for electronics used in Internet-of-Things (IoT), [9] human-machine interfaces, [10] and advanced healthcare. [11] Although significant progress has been made in academia, the practical application of flexible electronics in the industry is limited. Presently, thin-film photovoltaics and flexible displays mainly contribute to the flexible electronics market, with a noticeable presence held by radio frequency identification (RFID) tags and medical X-ray imagers. [12] Indeed, much of the success of present flexible electronic systems rely on the performance and reliability of thin-film The development of flexible and conformable devices, whose performance can be maintained while being continuously deformed, provides a significant step toward the realization of next-generation wearable and e-textile applications. Organic field-effect transistors (OFETs) are particularly interesting for flexible and lightweight products, because of their low-temperature solution processability, and the mechanical flexibility of organic materials that endows OFETs the natural compatibility with plastic and biodegradable substrates. Here, an in-depth review of two competing flexible OFET technologies, planar and vertical OFETs (POFETs and VOFETs, respectively) is provided. The electrical, mechanical, and physical properties of POFETs and VOFETs are critically discussed, with a focus on four pivotal applications (integrated logic circuits, light-emitting devices, memories, and sensors). It is pointed out that the flexible function of the relatively newer VOFET technology, along with its perspective on advancing the applicability of flexible POFETs, has not been reviewed so far, and the direct comparison regarding the performance of POFET-and VOFET-based flexible applications is most likely absent. With discussions spanning printed and wearable electronics, materials science, biotechnology, and environmental monitoring, this contribution is a clear stimulus to researchers working in these fields to engage toward the plentiful possibilities that POFETs and VOFETs offer to flexible electronics.
“…Moreover, VOFETs can be used to easily produce large-area ICs using printing techniques. This is usually considered as a problem in POFETbased ICs that usually contain less than 100 POFETs [214,[251][252][253][254][255][256] because of the low resolution and large feature size of most of the printing techniques. [257] Comparatively, the fabrication of POFETs on flexible substrates (both biorelevant and plastic) is a mature research area, with applications ranging from simple logic gates to unipolar and complementary ring oscillators.…”
Section: Discussion and Comparison Between Pofet-and Vofet-based Flex...mentioning
confidence: 99%
“…Moreover, VOFETs can be used to easily produce large‐area ICs using printing techniques. This is usually considered as a problem in POFET‐based ICs that usually contain less than 100 POFETs [ 214,251–256 ] because of the low resolution and large feature size of most of the printing techniques. [ 257 ]…”
“…[179] Although it shows great potential for low-temperature fabrication on flexible substrates and cost-effective large-area production, it is rarely used to manufacture printed organic ICs. The main challenge, in this context, is the absence of technology scaling, as most of the printed ICs contain less than 100 POFETs [214,[251][252][253][254][255][256] because of the low resolution and large feature size of most of the printing techniques. [257] Considering these limitations, Kwon et al demonstrated 3D monolithic integration of flexible printed POFETs to realize technology scaling.…”
Section: Application In Flexible Logic Gates Inverters and Oscillatorsmentioning
According to the forecast of Allied Market Research, the flexible electronics market is projected to reach $42.48 billion by 2027. It is estimated to revolutionize the lighting technology, power integration displays, and health monitoring systems. The popularity of flexible electronics is mainly due to the unique benefits of organic materials and devices that offer cost-effectiveness, low-temperature processability, mechanical softness, and shape adaptability, [5][6][7] which are difficult to obtain with traditional, complementary-metal-oxide-semiconductor (CMOS)-based rigid systems. [8] Over the past two decades, research interest in flexible electronic systems has grown exponentially, driven by the requirements of interface softness and shape adaptability for electronics used in Internet-of-Things (IoT), [9] human-machine interfaces, [10] and advanced healthcare. [11] Although significant progress has been made in academia, the practical application of flexible electronics in the industry is limited. Presently, thin-film photovoltaics and flexible displays mainly contribute to the flexible electronics market, with a noticeable presence held by radio frequency identification (RFID) tags and medical X-ray imagers. [12] Indeed, much of the success of present flexible electronic systems rely on the performance and reliability of thin-film The development of flexible and conformable devices, whose performance can be maintained while being continuously deformed, provides a significant step toward the realization of next-generation wearable and e-textile applications. Organic field-effect transistors (OFETs) are particularly interesting for flexible and lightweight products, because of their low-temperature solution processability, and the mechanical flexibility of organic materials that endows OFETs the natural compatibility with plastic and biodegradable substrates. Here, an in-depth review of two competing flexible OFET technologies, planar and vertical OFETs (POFETs and VOFETs, respectively) is provided. The electrical, mechanical, and physical properties of POFETs and VOFETs are critically discussed, with a focus on four pivotal applications (integrated logic circuits, light-emitting devices, memories, and sensors). It is pointed out that the flexible function of the relatively newer VOFET technology, along with its perspective on advancing the applicability of flexible POFETs, has not been reviewed so far, and the direct comparison regarding the performance of POFET-and VOFET-based flexible applications is most likely absent. With discussions spanning printed and wearable electronics, materials science, biotechnology, and environmental monitoring, this contribution is a clear stimulus to researchers working in these fields to engage toward the plentiful possibilities that POFETs and VOFETs offer to flexible electronics.
“…This work has a record transistor density of approximately 60 transistors per square centimetre for printed ICs when the 3D NAND design is considered to consist of four transistors (Fig. 7) 16,17,20,21,29–40 . Based on this technology, we could fabricate up to ≈2700 programmable transistors on the size of a standard credit card (85.60 × 53.98 mm), which is compatible with the transistor count of the first commercial 4-bit microprocessor.Fig.…”
Section: Resultsmentioning
confidence: 99%
“…The scaling capability of conventional silicon transistors, i.e., Moore’s law, which calls for the transistor density to be doubled every 18 months, has made ICs an excellent example of a general purpose technology 13 . Although organic transistors patterned by photolithography or shadow mask evaporation have been applied to microprocessors and smart tags 14,15 , most functional organic ICs fabricated by printing have less than a hundred transistors 16–21 . The progress in printed organic ICs has been slow because the low resolution (typically 10–100 μm) and large feature size (typically 100–200 μm) of current printing techniques have limited the transistor counts in processable areas 22 .…”
Direct printing of thin-film transistors has enormous potential for ubiquitous and lightweight wearable electronic applications. However, advances in printed integrated circuits remain very rare. Here we present a three-dimensional (3D) integration approach to achieve technology scaling in printed transistor density, analogous to Moore’s law driven by lithography, as well as enhancing device performance. To provide a proof of principle for the approach, we demonstrate the scalable 3D integration of dual-gate organic transistors on plastic foil by printing with high yield, uniformity, and year-long stability. In addition, the 3D stacking of three complementary transistors enables us to propose a programmable 3D logic array as a new route to design printed flexible digital circuitry essential for the emerging applications. The 3D monolithic integration strategy demonstrated here is applicable to other emerging printable materials, such as carbon nanotubes, oxide semiconductors and 2D semiconducting materials.
The future era of hyperconnected information technology demands smart wearable devices, which provide ubiquitous human‐oriented service platforms and imperceptible computing with hands‐free and lightweight gadgets. Wearable devices have progressively developed from accessories such as glasses, wrist bands, and watches to embedded types in fibers or textiles, skin tattoos, and even implanted in the user's body. As a crucial component of smart applications, the flexible electronic system should contain embedded active electronic components such as transistors and integrated circuitry for processing data acquired in sensors and transmitting them to wireless communication systems. The substrates of these flexible electronic systems have also expanded from flexible plastic substrates to conformable ones such as fabrics and textiles. Here, recent progresses in flexible electronic systems, composed of transistor‐based circuitry and active matrix built on plastics or textile substrates, with an emphasis on fabrication using the conventional technology for electronic materials, are reviewed. In addition, emerging application areas of smart wearable technologies in a health monitoring system are also presented.
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