Impact of Narrowing Density of States in Semiconducting Polymers on Performance of Organic Field-Effect Transistors.

To improve the performance of organic field-effect transistors (OFETs) employing π-conjugated polymers, a basic understanding of the relationships between the material properties and device characteristics is crucial. Although the density of states (DOS) distribution is one of the essential material properties of semiconducting polymers, insights into how the DOS shape affects the mobility (µ), subthreshold swing (S), and contact resistance (R ) in OFETs remain lacking. In this study, by combining sensitive DOS measurements and multilayered OFET structures, it is experimentally demonstrated that narrower DOS widths in the polymer channels lead to higher µ, smaller S, and lower R .

Determination of neurotransmitters in mouse brain using miniaturized and tableted QuEChERS for the sample preparation.

Neurotransmitters (NTs) are important endocrine molecules in the human body that have several characteristics and functions. Therefore, it is necessary to determine the accuracy and precision of the proposed method for the assessment of NTs functions. This study proposes a quick, easy, cheap, effective, rugged, and safe (QuEChERS) tablet for easy sample preparation and application to low-volume samples.

Reduction of Electric Current Loss by Aggregation-Induced Molecular Alignment of a Non-Fullerene Acceptor in Organic Photovoltaics.

Y6 is a recently developed non-fullerene electron acceptor (NFA) with dithienothiophen[3.2-]-pyrrolobenzothiadiazole as the central unit and improves the performance of organic photovoltaics (OPVs) in combination with many electron-donor polymers. Although Y6 has desirable electronic properties for OPVs, the origin of its superiority as an acceptor is unclear.

Triphenyleno[1,2-:7,8-']bis([1,2,5]thiadiazole) as a V-Shaped Electron-Deficient Unit to Construct Wide-Bandgap Amorphous Polymers for Efficient Organic Solar Cells.

The backbone shape of semiconducting polymers strongly affects their electronic properties and morphologies in films, yet the conventional design principle for building blocks focuses on using linear main chains to maintain high crystallinity. Here, we developed a V-shaped unit, triphenyleno[1,2-:7,8-']bis([1,2,5]thiadiazole) (TPTz), featuring two 1,2,5-thiadiazole rings fused to a triphenylene core with strong electron-withdrawing properties and an extended conjugation plane. We used TPTz to prepare a highly soluble copolymer, PTPTz-indacenodithiophene (IDT), which exhibited a wide bandgap of 1.

Highly Sensitive Evaluation of Density of States in Molecular Semiconductors by Photoelectron Yield Spectroscopy in Air.

Despite the critical importance of the density of states (DOS) to the electrical properties of molecular semiconductors, there are few reliable measurement methods for the DOS, especially for the edge regions with low DOS that determine the charge conduction. Here, we evaluate the DOS for occupied states with high sensitivity (down to 10 relative to the peak maxima) using a commercially available photoelectron yield spectroscopy (PYS) system operated in air. The conduction edges of the DOS for both the semiconducting polymers and molecules are expressed as a single Gaussian with no gap states with one exception.

Immobilization of Ethynyl-π-Extended Electron Acceptors with Amino-Terminated SAMs by Catalyst-Free Click Reaction.

Surface modification of SiO using a catalyst-free quantitative reaction between an amine and an ethynyl-π-extended naphthalenediimide was investigated. A post-reaction method, in which the catalyst-free reaction was performed at the surface after the formation of amino-terminated self-assembled monolayers (SAMs), resulted in dense, uniform modification of the SiO surface with the naphthalenediimide molecules. Both X-ray reflectivity and angle-resolved X-ray photoemission spectroscopy showed consistent results for the layer thickness and density.

Metal-intercalated aromatic hydrocarbons: a new class of carbon-based superconductors.

New carbon-based superconductors are synthesized by intercalating metal atoms into the solid-phase hydrocarbons picene and coronene. The highest reported superconducting transition temperature, T(c), of a hydrocarbon superconductor is 18 K for K(3)picene. The physics and chemistry of the hydrocarbon superconductors are extensively described for A(x)picene (A: alkali and alkali earth-metal atoms) for x = 0-5.

Air-assisted high-performance field-effect transistor with thin films of picene.

A field-effect transistor (FET) with thin films of picene has been fabricated on SiO2 gate dielectric. The FET showed p-channel enhancement-type FET characteristics with the field-effect mobility, mu, of 1.1 cm2 V-1 s-1 and the on-off ratio of >10(5).

Allelic characterization of the leaf-variegated mutation var2 identifies the conserved amino acid residues of FtsH that are important for ATP hydrolysis and proteolysis.

Arabidopsis var1 and var2 mutants exhibit leaf variegation. VAR1 and VAR2 encode similar FtsH metalloproteases (FtsH5 and FtsH2, respectively). We have previously found many variegated mutants to be allelic to var2.