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NAND logic circuit design and characteristics. (a) Circuit schematic of NAND device with zero-V GS -load p-type pseudo-CMOS design. (b) Photograph of fabricated NAND circuit. (c) Measured output voltage (V OUT ) and small-signal gain as a function of input voltage B (V IN_B ) for input voltage A V IN_A = 0 V and V IN_A = 10 V when V DD = − 10 V and V IN_A = 20 V when V DD = − 20 V. (d) Dynamic response of NAND logic circuit with input signals of frequencies, V IN_A = 0.5 kHz and V IN_A = 5 kHz.
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The low mobility and large contact resistance in organic thin-film transistors (OTFTs) are the two major limiting factors in the development of high-performance organic logic circuits. Here, solution-processed high-performance OTFTs and circuits are reported with a polymeric gate dielectric and 6,6 bis (trans-4-butylcyclohexyl)-dinaphtho[2,1-b:2,1-...
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... S6a. In OTFTs, the energy level misalignment between contacts and OSC is major contributor for higher contact resistance 13,15,43 . The work function of untreated Au contacts was measured to be 4.8 eV which created a hole injection barrier with the HOMO level of 4H-21DNTT (5.31 eV) and resulted in larger contact resistance of 9.4 kΩcm at − 20 V (Fig. S7). For PFBT treated Au contacts the work function was measured to be 5.58 eV, which suggested an efficient charge injection and nearly one order lowering of contact resistance. We concluded that the larger contact resistance with untreated Au contacts is owing to injection barrier due to energetic mismatch, since no major differences ...
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... further demonstrate the potential of 4H-21DNTT OTFT and assess the reproducibility of our fabrication process, we studied the performance of a pseudo-CMOS based NAND circuit, which is a basic building block to configure D-FF, shift registers, and counters. A schematic of the pseudo-CMOS logic-based NAND circuit is shown in Fig. 7a. The NAND circuit is composed of six p-type OTFTs (T1, T2, T3, T4, T5, and T6) with various W/L ratios. The channel length of each OTFT was l5 μm, the channel widths for transistors T1, T2, T3, T4, T5, and T6 were 300, 300, 600, 600, 1200, and 1200 μm, respectively, and the gate-to-source and gate-to-drain overlap (L OV ) was 30 μm. An ...
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... OTFTs (T1, T2, T3, T4, T5, and T6) with various W/L ratios. The channel length of each OTFT was l5 μm, the channel widths for transistors T1, T2, T3, T4, T5, and T6 were 300, 300, 600, 600, 1200, and 1200 μm, respectively, and the gate-to-source and gate-to-drain overlap (L OV ) was 30 μm. An image of the fabricated NAND circuit is shown in Fig. 7b. Figure 7c shows the static input-output voltage characteristics of NAND circuit (i) at a bias voltage of -20 V (V SS = − V DD ) with input V B swept linearly from 0 to 30 V for two V A inputs of 0 V and 20 V, and (ii) at a bias voltage of − 10 V (tuning voltage V SS = − V DD ) with input V B swept linearly from 0 to 20 V for two V A ...
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... image of the fabricated NAND circuit is shown in Fig. 7b. Figure 7c shows the static input-output voltage characteristics of NAND circuit (i) at a bias voltage of -20 V (V SS = − V DD ) with input V B swept linearly from 0 to 30 V for two V A inputs of 0 V and 20 V, and (ii) at a bias voltage of − 10 V (tuning voltage V SS = − V DD ) with input V B swept linearly from 0 to 20 V for two V A inputs of 0 V and − 10 V. At fixed V A inputs of − 20 V and − 10 V, the pseudo-CMOS-based NAND circuit exhibited good switching characteristics with small hysteresis. ...
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Citations
... In principle, it is desirable to have a gain as high as possible since higher gain delivers higher performance [25]. From a device point of view, high gain can be obtained by increasing the mobility, e.g. using semiconductors with high carrier mobility [26]. For a fixed technology, however, the semiconductor cannot be changed freely. ...
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... Polysilicon [1,2] and amorphous silicon [3,4] thin film transistors have become mainstream in driving AMLCD and AMOLED due to their mature processing technology. In addition, organic thin film transistors (OTFT) [5][6][7] has also been proposed and developed during the last 30 years, due to their low-temperature process that is compatible with flexible substrates. Being the important evaluation parameter of OTFT, the carrier mobility has been significantly improved, for the conventional small molecule and polymer thin film transistor, the carrier mobility has reached to the level of a:Si thin film transistor, while for organic single crystal thin film transistor, the carrier mobility even reached the level of 10 2 • ⁄ [8,9]. ...
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This suggested that the source/drain tunneling structure can indeed improve the electrical characteristics of bottom-contact OTFT, and further improvement is necessitated to achieve the high performance comparable to top-contact device.
... One method to lower electron injection by raising the height of the electron injection barrier is the dual-gate structure. The electrons can be repelled from the OSC layer, and the leakage current can be reduced by applying a negative voltage to the back gate [81][82][83]. ...
Ion-sensitive field-effect transistors (ISFETs) are used as elementary devices to build many types of chemical sensors and biosensors. Organic thin-film transistor (OTFT) ISFETs use either small molecules or polymers as semiconductors together with an additive manufacturing process of much lower cost than standard silicon sensors and have the additional advantage of being environmentally friendly. OTFT ISFETs’ drawbacks include limited sensitivity and higher variability. In this paper, we propose a novel design technique for integrating extended-gate OTFT ISFETs (OTFT EG-ISFETs) together with dual-gate OTFT multiplexers (MUXs) made in the same process. The achieved results show that our OTFT ISFET sensors are of the state of the art of the literature. Our microsystem architecture enables switching between the different ISFETs implemented in the chip. In the case of sensors with the same gain, we have a fault-tolerant architecture since we are able to replace the faulty sensor with a fault-free one on the chip. For a chip including sensors with different gains, an external processor can select the sensor with the required sensitivity.
... 24 These high charge carrier mobilities and exceptional stabilities have opened up more pathways for implementing organic semiconductors in the fabrication of high performance semiconductor devices including organic thin film transistors, [25][26][27][28] organic gas sensors, [29][30][31][32][33] organic optoelectronic devices, [34][35][36][37][38][39][40] and complimentary circuits. [41][42][43] Nevertheless, a challenging issue in organic semiconductor growth is the control of crystallization and morphology. This is mainly caused by the intrinsic crystal misorientation when the organic semiconductor is grown in solution, as reported in many small molecular organic semiconductors. ...
Solution processed, flexible electronics has garnered great research attention in the last decade, and has found promising applications in semiconductor device fabrication such as in thin film transistors and organic gas sensors. Binary solvents have been demonstrated to exert an important impact on the semiconductor dissolution, crystal growth, phase segregation, film morphology, crystal alignment, film crystallinity and charge transport of organic semiconductors. In this article, we conducted a comprehensive review on the effect of engineering binary solvents on the crystallization of organic semiconductors. By studying the organic semiconductor 6,13-bis(triisopropylsilylethynyl)pentacene as a representative example, we showcase that the optimization of solvent choices can play a vital role in modulating the solvent evaporation, intermolecular interaction, supramolecular aggregation, semiconductor nuclei, crystal orientation and charge carrier mobilities. Based on a detailed review of these important works, we wish to shed light on the great potential of fine-tuning the solvent choices in order to optimize the charge transport and electrical performance of flexible electronic devices.
... OFETs have, thus, been researched for numerous applications like sensing, display, and smart diagnosis. [1][2][3][4][5] This demands high performance and high stability for both p-type and n-type devices, which is essential for complementary circuitry. 6 Unfortunately, n-type OFETs develop relatively slower than the p-type counterpart, mainly due to the poor charge injection at contacts. ...
N-type organic field-effect transistors have suffered from poor environmental instability. Here, we report that, by using nickel (Ni) instead of the commonly used gold (Au) as contact electrodes, n-type polymer transistors showed much improved stability upon annealing in nitrogen and exposure to air. In particular, Au-contacted devices exhibited pronounced ambipolar conduction whereas Ni-contacted devices retained fairly good unipolar properties. The results are important to build stable n-type polymer transistors at low cost.
... Representative organic semiconductors applicable for large-area printing processes are shown in Fig. 2(c). [7][8][9][10][11][12] Briefly, they can be categorized into two systems: rod-like πelectron cores bearing side chains at (1) the short-and (2) the long-axis end, where TIPS-pentacene is the representative of the category (1), while the others shown in Fig. 2(e) belong to category (2). It is noteworthy that bulky groups represented by (trialkylsilyl)ethynyl group are generally employed for materials in category (1), whereas those in category (2) generally bear flexible alkyl groups as the side chain. ...
... These results show the potential application of the printed 2D single crystals for practical IoT devices, which is actually in progress with various organic semiconductor materials. 12,57) The blade width is a crucial factor to determine the coverage area and the overall uniformity of the single crystals and the integrated circuit design (Fig. 8). Starting research on CEC with a 20 mm wide homemade blade, 49) a 1 mm wide blade was designed to separately and alternately paint p-type and n-type organic semiconductor single crystals on the same substrate, 58) where the length of the single crystals can be larger than a few centimeters. ...
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... 62 Bilgaiyan et al. reported the solution shearing of a 6,6 bis-(trans-4-butylcyclohexyl)-dinaphtho[2,1-b:2,1-f]thieno [3,2-b]thiophene (4H-21DNTT) organic semiconductor based thin film transistor and obtained a mobility of 10.5 cm 2 V À1 s À1 . 63 The 4H-21DNTT based CMOS inverter circuit showed sharp switching behaviors with a 31.5 signal gain. Second, substrate patterning based methods involve the tuning of substrate wettability by using surfactant treatment and/or photolithography patterning, which can effectively confine the deposition of organic semiconductor solutions as well as the subsequent crystal growth and alignment. ...
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... Recently, Anubha Bilgaiyan, et. al. [8] reported a new cyclopentyl-substituted (4H-21DNTT) on flexible ITO. It can be observed that 4H-21DNTT has sufficient mobility and on-off ratio for TFT realization. ...
... In the OSC layer the weak pi (π) electrons are free to move within the entire layer. The alternative bonding and antibonding create a forbidden energy gap, this is represented as 'Bandgap' 4H-21DNTT Chemical Structure [8] In OSC has rigid molecular structure that present over the extended-electron framework. The charge transportation on intermolecular is done via − overlap in solid state. ...
... The electron affinity ( ) of 4H-21DNTT is 1.8 eV. The ionized energy of 4H-21DNTT is 5.2 eV [8], which is nearby the gold work function (Φ M ) 5.5 eV [10]. So, the gold contacts are very suitable for this OSC. ...
