It is now widely accepted that skin sensitivity will be very important for future robots used by humans in daily life for housekeeping and entertainment purposes. Despite this fact, relatively little progress has been made in the field of pressure recognition compared to the areas of sight and voice recognition, mainly because good artificial ''electronic skin'' with a large area and mechanical flexibility is not yet available. The fabrication of a sensitive skin consisting of thousands of pressure sensors would require a flexible switching matrix that cannot be realized with present silicon-based electronics. Organic field-effect transistors can substitute for such conventional electronics because organic circuits are inherently flexible and potentially ultralow in cost even for a large area. Thus, integration of organic transistors and rubber pressure sensors, both of which can be produced by low-cost processing technology such as large-area printing technology, will provide an ideal solution to realize a practical artificial skin, whose feasibility has been demonstrated in this paper. Pressure images have been taken by flexible active matrix drivers with organic transistors whose mobility reaches as high as 1.4 cm 2 ͞V⅐s. The device is electrically functional even when it is wrapped around a cylindrical bar with a 2-mm radius. R ecognition of tactile information will be very important for future generations of robots used by humans in daily life for housekeeping and entertainment purposes (1, 2). An important step to obtain good artificial ''electronic skin'' is to fabricate large-area pressure sensors with mechanical f lexibility. Despite this fact, relatively little progress has been made in the field of pressure recognition compared to the areas of sight and voice recognition (1, 2). Even though f lexible materials such as polymers and rubbers have been used to make sensing components, the fabrication of a sensitive skin consisting of thousands of pressure sensors would also require a f lexible switching matrix that cannot be realized with present-day silicon-based electronics.Organic field-effect transistors (3-13) are inherently f lexible and very inexpensive to fabricate even for large areas (9, 10), and hence are adequate for use as a switching matrix in a pressure sensor. The minimum bending diameter reported so far, however, has been only 30 mm (11) because inorganic materials were still used in many previous transistors for some components such as gate insulators (SiO 2 , Al 2 O 3 ) and base films (glass, silicon). Moreover, the highest mobilities reported so far for plastic transistors have been around 0.1 cm 2 ͞V⅐s (5), much lower than the best values around 2-5 cm 2 ͞V⅐s obtained with hard substrates (13). The above two points have been major hurdles to the application of organic transistors to large-area f lexible electronics.In this article, we demonstrate an application of organic transistors in which all of the materials are soft except the electrodes. The organic transistors are integrated w...

Skin-like sensitivity, or the capability to recognize tactile information, will be an essential feature of future generations of robots, enabling them to operate in unstructured environments. Recently developed large-area pressure sensors made with organic transistors have been proposed for electronic artificial skin (E-skin) applications. These sensors are bendable down to a 2-mm radius, a size that is sufficiently small for the fabrication of human-sized robot fingers. Natural human skin, however, is far more complex than the transistor-based imitations demonstrated so far. It performs other functions, including thermal sensing. Furthermore, without conformability, the application of E-skin on three-dimensional surfaces is impossible. In this work, we have successfully developed conformable, flexible, large-area networks of thermal and pressure sensors based on an organic semiconductor. A plastic film with organic transistor-based electronic circuits is processed to form a net-shaped structure, which allows the E-skin films to be extended by 25%. The net-shaped pressure sensor matrix was attached to the surface of an egg, and pressure images were successfully obtained in this configuration. Then, a similar network of thermal sensors was developed with organic semiconductors. Next, the possible implementation of both pressure and thermal sensors on the surfaces is presented, and, by means of laminated sensor networks, the distributions of pressure and temperature are simultaneously obtained.electronic artificial skin ͉ large-area sensor O rganic field-effect transistors (1-3) and their integrated circuits (4-6) have attracted considerable attention because of attributes that complement silicon-based large-scale integrations, devices that are high-performance but expensive. Organic transistors can be manufactured on plastic films at low (ambient) temperatures; therefore, they are mechanically flexible (7) and potentially inexpensive to manufacture. Two major applications drive recent studies of organic transistors. The first includes flexible displays such as paper-like displays or e-paper, in which electric inks or other media are driven by organic transistor active matrixes (8, 9). The second comprises radio frequency identification tags (10). The printable features (11-15) of organic transistors should facilitate the implementation of radio frequency identification on packages.We have recently demonstrated another promising application: a flexible pressure sensor matrix (16,17), in which organic transistor active matrixes are used to read out pressure data from sensors. This new pressure sensor (16, 17) could be very suitable for electronic artificial skin (E-skin), which will be an essential feature of robots, enabling them to operate in unstructured environments (18). Although the mobility of organic semiconductors is known to be about two or three orders of magnitude less than that of poly-and single-crystalline silicon, the slower speed is tolerable for most applications of large-area sensors. For E-skin ...

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Using organic transistors with a floating gate embedded in hybrid dielectrics that comprise a 2-nanometer-thick molecular self-assembled monolayer and a 4-nanometer-thick plasma-grown metal oxide, we have realized nonvolatile memory arrays on flexible plastic substrates. The small thickness of the dielectrics allows very small program and erase voltages (< or = 6 volts) to produce a large, nonvolatile, reversible threshold-voltage shift. The transistors endure more than 1000 program and erase cycles, which is within two orders of magnitude of silicon-based floating-gate transistors widely employed in flash memory. By integrating a flexible array of organic floating-gate transistors with a pressure-sensitive rubber sheet, we have realized a sensor matrix that detects the spatial distribution of applied mechanical pressure and stores the analog sensor input as a two-dimensional image over long periods of time.

A simple yet realistic MOS model, namely the a-power law MOS model, is introduced to include the carrier velocity saturation effect, which becomes eminent in short-channel MOSFET's. The model is an extension of Shockley's square-law MOS model in the saturation region. Since the model is simple, it can be applied for handling MOSFET circuits analytically and can predict the circuit behavior in the submicrometer region. Using the model, closed-form expressions are derived for the delay, the short-circuit power, and the transition voltage of CMOS invert- ers. The resultant delay expression includes input waveform slope effects and parasitic drain/source resistance effects and can be used in simulation and/or optimization CAD tools. It is concluded that the CMOS inverter delay becomes less sensitive to the input waveform slope and short-circuit dissipation increases as the carrier velocity saturation effects get severer in short-channel MOSFET's.A. Richard Newton (S'73-M'78-SM86-F'88) was born in Melbourne. Australia, on July 1, 1951. He received the B.Eng. (elec.) and M.Eng. Sci. degrees from the

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less than one decade, the power conversion efficiency (PCE) of perovskite solar cells (PSCs) have rapidly been achieved to 22.7%, i.e., a level that is nearly on par with traditional silicon solar cells. [2] In addition, efficient, flexible, [3] color-tunable, and semitransparent PSCs [4] have also been demonstrated, showing the merit for application in portable devices and building-integrated photovoltaics (BIPV). Therefore, PSCs are considered to be the most promising candidate for next-generation high efficiency solar cell technology, and they hold great potential in photovoltaic market in the near future.Perovskite has a general ABX 3 structure. For newly emerged organic-inorganic halide perovskites for photovoltaic application, A represents methylammonium (namely, CH 3 NH 3 + , abbreviated as MA + ), formamidinium (namely, CH(NH 2 ) 2 + , abbreviated as FA + ), and Cs + (including its mixture with MA + and/or FA + ), B represents metal ions, including Pb 2+ and/or Sn 2+ , and X represents halide anions, such as I − , Br − , and Cl − (including the mixture of them). [1f,5] The basic structures of PSCs are shown in Figure 1a. Generally, there are two kinds of structures, namely, mesoporous structure and planar structure. A mesoporous-structured PSC consists of transport conductive oxide (TCO)/compact layer TiO 2 (cl-TiO 2 )/mesoporous layer (TiO 2 or Al 2 O 3 )/perovskite/ hole transport layer (HTL)/metal anode. The planar-structured PSC has an architecture: cathode/electron transport layer (ETL)/ perovskite/HTL/anode for conventional structure or anode/ HTL/perovskite/ETL/cathode for inverted structure. Both of the mesoporous and the planar PSCs are reported to yield high PCE. [6] As can be seen from Figure 1a, a PSC consists of several layers, including electrodes (cathode and anode), absorber layer, and carrier transport layers. The absorber layer is basically metal halide perovskite (such as MAPbI 3 and FAPbI 3 ), [7] mixed metal halide perovskite (such as FA 1−x MA x Pb(I 1−y Br y ) 3 ), [8] or inorganic perovskite (CsPbI 3 ). [9] For the ETL or HTL, it can be either inorganic (such as TiO 2 , SnO 2 , ZnO, CuI, NiO, etc.) [10] or organic material (such as phenyl-C61-butyric acid methyl ester (PCBM), fullerene (C 60 ), 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD), poly(3,4ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS), copper(I) thiocyanate (CuSCN), polytriarylamine (PTAA), poly(3-hexylthiophene) (P3HT), etc.). [11] Figure 1b simply shows a schematic representation of the interfaces and the energy levels in a PSC with planar structure (regardless of The rapid progress of organic-inorganic metal halide perovskite solar cells (PSCs) has attracted broad interest in photovoltaic community. A typical PSC consists of anode/cathode, a perovskite layer as absorber, and carrier transport layer(s) (electron/hole transport layer(s)), which are stacked together, resulting in multi-interfaces between these layers. Charge extraction and transport in these solar...

We have fabricated very flexible pentacene field-effect transistors with polyimide gate dielectric layers on plastic films with a mobility of 0.3cm2∕Vs and an on/off ratio of 105, and have measured their electrical properties under various compressive and tensile strains while changing the bending radius of the base plastic films systematically. We have found that the change in source-drain current with bending radius is reproducible and reversible when the bending radius is above 4.6mm, which corresponds to strains of ∼1.4±0.1%. Furthermore, the change in source-drain current does not depend on the direction of strain versus direction of current flow.