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Split-gate organic field-effect transistors have been developed for high-speed operation. Owing to the combination of reduced contact resistance and minimized parasitic capacitance, the devices have fast switching characteristics. The cutoff frequencies for the vacuum-evaporated devices and the solution-processed devices are 20 and 10 MHz, respectively. A speed of 10 MHz is the fastest device reported so far among solution-processed organic transistors.

easily realized in the top-contact geometry, the limitation in minimum separation of source and drain electrodes prevents further advancement in on-off switching speed; it is essential to realize OFETs with a high-mobility semiconductor and a short channel length L , because the maximum circuit operating frequency is proportional to the transconductance g m and inversely proportional to L 2 . Moreover, the technique using shadow masks cannot be applied to mass-producible processes to fabricate integrated OFETs in an identical substrate with high yield.Photolithography is the well-established technique to fabricate fi ne patterns, though it is rarely employed in the top-contact OFETs because conventional organic semiconductor layers are seriously damaged by solutions used for common wet processes in the method. A method using orthogonal fl uorinated photoresist was proposed, [ 10,11 ] which enables to make fi ne patterns without dissolution of organic semiconductors. Though the method enables the fabrication of micro-and nano-scale OFETs, it has not matured yet to be applied for circuitries with short-channel and high-mobility semiconductor devices mainly because of the very large contact resistances. [ 11 ] In OFETs with bottom-contact geometry, photolithography is more often employed because the electrode patterning is fi nished before the semiconductor deposition. However, a major concern for the bottom-contact OFETs with a polycrystalline semiconductor fi lm relates to the molecular disorder occurring in the vicinity of the metal electrodes. [ 12 ] To overcome this problem, electrode surface modifi cations on gold fi lms by thiol-based selfassembled monolayers [ 13,14 ] or UV/O 3 treatment [ 15 ] are effective to reduce the contact resistance, however, these devices suffer from irreproducibility and poor long-term reliability due to chemical instability of most Au-thiolate SAMs. [ 13 ] In this communication, we report for the fi rst time a micropatterning process based on photolithography with simple wetetching of gold electrodes deposited directly on pristine organic fi lms without any adverse effect of residual photoresist. Since the wet-etching of gold is governed by iodide/iodine redox reaction, it is essential to use organic semiconductor materials that are robust to the reaction. Employing a newly developed highmobility organic semiconductor materials with tuned ionization potential, these processes are indeed suited to fabricate fi ne-pitch electrodes with low contact resistance, so that the highest cut-off frequency of 19 MHz is demonstrated for p-type transistors.In order to examine the robustness of organic semiconductors to the gold wet-etching process, we have carefully Based on the recent development of high-mobility and organic semiconductors, [1][2][3][4] organic fi eld-effect transistors (OFETs) offer promising prospects to realize such attractive applications as high-speed fl exible displays, fl exible radio frequency identifi cation (RF-ID) tags, and light-weight wearable smartsensing logics....

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the other hand, it was recently reported by our group that inchsize single-crystalline fi lms with unprecedentedly high carrier mobility can be fabricated from solution using a simple "edgecasting" method. [11][12][13] In this study, we aim to link the highmobility of solution-processed organic crystalline fi lms to a high dynamic response in organic transistors for both p-type and n-type operation by micropatterning the crystalline semiconductors and source/drain electrodes. The cut-off frequency f c of a transistor in the linear regime is described aswhere V D is the applied drain voltage, and L and W are the channel length and width, respectively. µ eff is the effective carrier mobility of an organic semiconductor, including the effects of contact resistance, C para is the parasitic gate capacitance, and c i WL represents the channel capacitance. In the saturation regime, V D is replaced by the gate voltage V G . From Equation ( 1) , it is clear that short-channel high-mobility transistors are strongly important to raise up the maximum operational speed of organic transistors. To realize a high fi eld-effect mobility in a short-channel device, it is crucial to reduce the contact resistance between the organic materials and the contact electrodes, which has been a challenging issue in organic transistors. In this Communication, top-contact organic confi gurations were adopted to realize extremely low contact resistances of 123 Ω cm for p-type transistors and 1.2 kΩ cm for n-type transistors, in which the contact electrodes were fabricated using photolithography process on solution-processed organic semiconductors. Complementary ring oscillators consisting of p-type and n-type transistors were demonstrated in ambient conditions to examine the operational speed of the organic circuits. Moreover, organic rectifi ers based on high-speed p-type transistors in which the drain and gate electrodes were diodeconnected were examined to determine their dynamic response speed in rectifying AC signals to DC output voltages at frequencies above 22 MHz. In the design of logic circuits, complementary circuits have the advantage of low power consumption, so the mainstream advancement of silicon technology has been based on complementary metal-oxide-semiconductor (CMOS) circuits. In organic transistors, stable n-type operation in ambient conditions has been a crucial issue because of the unstable Organic complementary circuits based on organic semiconductors have been proposed to enable attractive devices such as fl exible, or wearable organic devices. [1][2][3][4][5] Radio-frequency identifi cation (RFID) tags are one prospective application because organic devices are low-cost, light-weight, and fl exible, which are attractive features for this application. [6][7][8] One of the most important features of organic semiconductor materials is the strong self-aggregation of molecules, which enables fi ne crystalline fi lms to be easily formed, even at room temperature. This strong self-aggregation of organic materials also enables ...

High carrier-mobility organic field-effect transistors are developed employing high-k gate dielectrics so that unprecedentedly high transconductance is realized. 2,9-didecyl-dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (C10-DNTT) solution-crystallized films are coated on hybrid gate insulators of silane self-assembled monolayers and high-k Al2O3 formed by atomic-layer-deposition. Intrinsically high carrier mobility exceeding 10 cm2/Vs in the crystalline C10-DNTT is preserved even on the high-k gate insulators because of suppressed coupling of the field-induced carriers to the polarization of the dielectrics.

Epidermal growth factor receptor–tyrosine kinase inhibitor (EGFR-TKI) resistance is one of the most important problems in lung cancer therapy. Lung adenocarcinoma with EGFR-TKI resistance was reported to have higher abilities of invasion and migration than cancers sensitive to EGFR-TKI, but the function of matrix metalloproteinases (MMPs) has not been explored in EGFR-TKI–resistant lung adenocarcinoma. This study aims to clarify the significance of MMP-1 in EGFR-TKI–resistant lung adenocarcinoma. From the results of in vitro studies of migration and invasion assays using EGFR-TKI–sensitive and –resistant cell lines and phosphorylation antibody arrays using EGF and rapamycin, we first demonstrate that overexpression of MMP-1, which might follow activation of a mammalian target of rapamycin (mTOR) pathway, plays an important role in the migration and invasion abilities of EGFR-TKI–resistant lung adenocarcinoma. Additionally, immunohistochemical studies using 89 cases of lung adenocarcinoma demonstrate that high expression of MMP-1 is significantly correlated with poor prognosis and factors such as smoking history and the subtype of invasive mucinous adenocarcinoma. These are consistent with the results of this in vitro study. To conclude, this study provides insights into the development of a possible alternative therapy manipulating MMP-1 and the mTOR signaling pathway in EGFR-TKI–resistant lung adenocarcinoma.

Background:Lung adenocarcinoma (LADCA) patients with epidermal growth factor receptor (EGFR) mutations are in general associated with relatively high clinical response rate to EGFR-tyrosine kinase inhibitors (TKIs) but not all responded to TKI. It has therefore become important to identify the additional surrogate markers regarding EGFR-TKI sensitivity.Methods:We first examined the effects of EGFR-TKIs, gefitinib and erlotinib, upon cell proliferation of lung adenocarcinoma cell lines. We then evaluated the gene profiles related to EGFR-TKI sensitivity using a microarray analysis. Results of microarray analysis led us to focus on carcinoembryonic antigen-related cell adhesion molecule (CEACAM) family, CEACAM 3, 5, 6, 7, and 19, as potential further surrogate markers of EGFR-TKI sensitivity. We then examined the correlation between the status of CEACAM 3, 5, 6, 7, and 19 immunoreactivity in LADCA and clinicopathological parameters of individual cases.Results:In the cases with EGFR mutations, the status of all CEACAMs examined was significantly higher than that in EGFR wild-type patients, but there were no significant differences in the status of CEACAMs between TKI responder and nonresponder among 22 patients who received gefitinib therapy. However, among 115 EGFR mutation-negative LADCA patients, both CEACAM6 and CEACAM3 were significantly associated with adverse clinical outcome (CEACAM6) and better clinical outcome (CEACAM3).Conclusion:CEACAMs examined in this study could be related to the presence of EGFR mutation in adenocarcinoma cells but not represent the effective surrogate marker of EGFR-TKI in LADCA patients. However, immunohistochemical evaluation of CEACAM3/6 in LADCA patients could provide important information on their clinical outcome.