Organic thin-film transistors (OTFTs) have lived to see great improvements in recent years. This review presents new insight into conduction mechanisms and performance characteristics, as well as opportunities for modeling properties of OTFTs. The shifted focus in research from novel chemical structures to fabrication technologies that optimize morphology and structural order is underscored by chapters on vacuum-deposited and solution-processed organic semiconducting films. Finally, progress in the growing field of the n-type OTFTs is discussed in ample detail. The Figure, showing a pentacene film edge on SiO2, illustrates the morphology issue.

Organic Thin Film Transistors for Large Area Electronics

Organic semiconducting oligomers for use in thin film transistors.

In this paper we review recent progress in materials, fabrication processes, device designs, and applications related to organic thin-film transistors (OTFTs), with an emphasis on papers published during the last three years. Some earlier papers that played an important role in shaping the OTFT field are included, and a number of previously published review papers that cover that early period more completely are referenced. We also review in more detail related work that originated at IBM during the last four years and has led to the fabrication of high-performance organic transistors on flexible, transparent plastic substrates requiring low operating voltages.

Organic thin-film transistors: a review of recent advances

During the last two decades atmospheric (or high) pressure non-thermal plasmas in and in contact with liquids have received a lot of attention in view of their considerable environmental and medical applications. The simultaneous generation of intense UV radiation, shock waves and active radicals makes these discharges particularly suitable for decontamination, sterilization and purification purposes. This paper reviews the current status of research on atmospheric pressure non-thermal discharges in and in contact with liquids. The emphasis is on their generation mechanisms and their physical characteristics.

http://iopscience.iop.org/article/10.1088/0022-3727/42/5/053001/pdf

Non-thermal plasmas in and in contact with liquids

The cost-effective production of flexible electronic components will profit considerably from the development of solution-processable, organic semiconductor materials. Particular attention is focused on soluble semiconductors for organic field-effect transistors (OFETs). The hitherto differentiation between "small molecules" and polymeric materials no longer plays a role, rather more the ability to process materials from solution to homogeneous semiconducting films with optimal electronic properties (high charge-carrier mobility, low threshold voltage, high on/off ratio) is pivotal. Key classes of materials for this purpose are soluble oligoacenes, soluble oligo- and polythiophenes and their respective copolymers, and oligo- and polytriarylamines. In this context, micro- or nanocrystalline materials have the general advantage of somewhat higher charge-carrier mobilities, which, however, could be offset in the case of amorphous, glassy materials by simpler and more reproducible processing.

Organic semiconductors for solution-processable field-effect transistors (OFETs).

Purpose 
Nonequilibrium atmospheric pressure plasma (NEAPP) therapy has recently been focused on as a novel medical practice. Using cells with acquired paclitaxel/cisplatin resistance, we elucidated effects of indirect NEAPP-activated medium (NEAPP-AM) exposure on cell viability and tumor growth in vitro and in vivo.


Methods 
Using chronic paclitaxel/cisplatin-resistant ovarian cancer cells, we applied indirect NEAPP-exposed medium to cells and xenografted tumors in a mouse model. Furthermore, we examined the role of reactive oxygen species (ROS) or their scavengers in the above-mentioned EOC cells.


Results 
We assessed the viability of NOS2 and NOS3 cells exposed to NEAPP-AM, which was prepared beforehand by irradiation with NEAPP for the indicated time. In NOS2 cells, viability decreased by approximately 30% after NEAPP-AM 120-sec treatment (P<0.01). The growth-inhibitory effects of NEAPP-AM were completely inhibited by N-acetyl cysteine treatment, while L-buthionine-[S, R]-sulfoximine, an inhibitor of the ROS scavenger used with NEAPP-AM, decreased cell viability by 85% after NEAPP-AM 60-sec treatment(P<0.05) and by 52% after 120 sec, compared to the control (P<0.01). In the murine subcutaneous tumor-formation model, NEAPP-AM injection resulted in an average inhibition of the NOS2 cell-inoculated tumor by 66% (P<0.05) and NOS2TR cell-inoculated tumor by 52% (P<0.05), as compared with the control.


Conclusion 
We demonstrated that plasma-activated medium also had an anti-tumor effect on chemo-resistant cells in vitro and in vivo. Indirect plasma therapy is a promising treatment option for EOC and may contribute to a better patient prognosis in the future.

https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0081576&type=printable

Effect of Indirect Nonequilibrium Atmospheric Pressure Plasma on Anti-Proliferative Activity against Chronic Chemo-Resistant Ovarian Cancer Cells In Vitro and In Vivo

Glioblastoma brain tumor cells and normal astrocytes were treated with plasma-activated medium (PAM). Cell proliferation assays showed that glioblastoma cells were selectively killed by PAM. PAM induced morphological changes consistent with apoptosis in glioblastoma cells and the cells decreased in size. We confirmed that those cells induced apoptosis using an apoptotic molecular marker, cleaved Caspase3/7. To elucidate the molecular mechanisms of PAM-mediated apoptosis in glioblastoma cells, we investigated the effects of survival signal transduction pathways. We found that PAM downregulated the expression of AKT kinase, a marker molecule in a survival signal transduction pathway. These results suggest that PAM may be a promising tool for therapy of glioblastoma brain tumors by downregulating the survival signals in cancers.

Plasma-Activated Medium Selectively Kills Glioblastoma Brain Tumor Cells by Down-Regulating a Survival Signaling Molecule, AKT Kinase

Two independent ovarian cancer cell lines and fibroblast controls were treated with nonequilibrium atmospheric pressure plasma (NEAPP). Most ovarian cancer cells were detached from the culture dish by continuous plasma treatment to a single spot on the dish. Next, the plasma source was applied over the whole dish using a robot arm. In vitro cell proliferation assays showed that plasma treatments significantly decreased proliferation rates of ovarian cancer cells compared to fibroblast cells. Flow cytometry and western blot analysis showed that plasma treatment of ovarian cancer cells induced apoptosis. NEAPP could be a promising tool for therapy for ovarian cancers.

Selective killing of ovarian cancer cells through induction of apoptosis by nonequilibrium atmospheric pressure plasma

Field‐effect transistors (FETs) have been prepared using thin films of alkyl substituted oligothiophenes. These compounds bring about a significant increase in the source‐drain channel current when compared to the conventional nonsubstituted oligothiophenes. The increased channel current mostly results from the enhanced carrier mobility of the material. We report that the FETs are readily made by a single routine process of casting or evaporation.

Field‐effect transistors using alkyl substituted oligothiophenes

We synthesized carbon nanowalls (CNWs) using radical injection plasma-enhanced chemical vapor deposition. The initial growth process of CNWs was investigated with and without O2 gas addition to a C2F6 capacitively coupled plasma with H radical injection. In the case of the CNW synthesis without the addition of O2 gas, scanning electron microscopy (SEM), transmission electron microscopy, x-ray photoelectron spectroscopy (XPS), and Raman spectroscopy revealed that a 10-nm-thick interface layer composed of nanoislands was formed on a Si substrate approximately 1 min prior to CNW formation. In contrast, with O2 gas addition, SEM and XPS revealed that an interface layer was not formed and that CNWs were grown directly from nanoislands. Moreover, Raman spectroscopy suggested that the interface layer was composed of amorphous carbon and that O2 gas addition during CNW growth is effective for achieving a high graphitization of CNWs. Therefore, O2 gas addition has the effect of reducing the amorphicity and disorder of CNWs and controlling CNW nucleation.

Hiroyuki Kano

Papers

Effect of Indirect Nonequilibrium Atmospheric Pressure Plasma on Anti-Proliferative Activity against Chronic Chemo-Resistant Ovarian Cancer Cells In Vitro and In Vivo

Plasma-Activated Medium Selectively Kills Glioblastoma Brain Tumor Cells by Down-Regulating a Survival Signaling Molecule, AKT Kinase

Selective killing of ovarian cancer cells through induction of apoptosis by nonequilibrium atmospheric pressure plasma

Field‐effect transistors using alkyl substituted oligothiophenes

Initial growth process of carbon nanowalls synthesized by radical injection plasma-enhanced chemical vapor deposition