No abstract

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 ...

A new class of solution-processable thieno[3,2-f:4,5-f′]bis[1]benzothiophene (TBBT-V) semiconductors are facilely synthesized and fully investigated.

We have developed a high resolution resist for laser thermal lithography and a fabrication method for this resist. We designed a resist material which has specific desired properties. We aimed to raise the gasification temperature and achieve a sharply peaked temperature profile so that holes are formed only in the center of the laser spot. We were able to perform lithography with a half pitch of 40 nm. Furthermore, using the result of this lithography as a dry etching mask, we were able to perform dry etching on a number of materials, including SiO 2 and sapphire.

Circular dichroism (CD), defined as the differential absorption of left-and right-handed circularly polarized light (CPL), is a useful spectroscopic technique for structural studies of biological systems composed of chiral molecules. The present study evaluated the effects of CPL on germination, hypocotyl elongation and biomass production of Arabidopsis and lettuce. Higher germination rates were observed when Arabidopsis and lettuce seedlings were irradiated with red right-handed CPL (R-CPL) than with red left-handed CPL (L-CPL). Hypocotyl elongation was effectively inhibited when Arabidopsis and lettuce seedlings were irradiated with red R-CPL than with red L-CPL. This difference was not observed when a phytochrome B (phyB) deficient mutant of Arabidopsis was irradiated, suggesting that inhibition of elongation by red R-CPL was mediated by phyB. White R-CPL induced greater biomass production by adult Arabidopsis plants, as determined by their fresh shoot weight, than white L-CPL. To determine the molecular basis of these CPL effects, CD spectra and the effect of CPL on the photoreaction of a sensory module of Arabidopsis phyB were measured. The red lightabsorbing form of phyB showed a negative CD in the red light-absorbing region, consistent with the results of germination, inhibition of hypocotyl elongation and biomass production. L-CPL and R-CPL, however, did not differ in their ability to induce the interconversion of the red light-absorbing and far-red light-absorbing forms of phyB. These findings suggest that these CPL effects involve phyB, along with other photoreceptors and the photosynthetic process.