p-n heterojunctions composed of two-dimensional molecular crystals for high-performance ambipolar organic field-effect transistors

10.1063/5.0048790APL Materials9505110

P-n heterojunctions composed of two-dimensional molecular crystals for high-performance ambipolar organic field-effect transistors

10.1063/5.0048790APL Materials9505110

Asymmetric Chemical Functionalization of Top-Contact Electrodes: Tuning the Charge Injection for High-Performance MoS2 Field-Effect Transistors and Schottky Diodes

International audienceThe fabrication of high-performance (opto-)electronic devices based on 2D channel materials requires the optimization of the charge injection at electrode–semiconductor interfaces. While chemical functionalization with chemisorbed self-assembled monolayers has been extensively exploited to adjust the work function of metallic electrodes in bottom-contact devices, such a strategy has not been demonstrated for the top-contact configuration, despite the latter being known to offer enhanced charge-injection characteristics. Here, a novel contact engineering method is developed to functionalize gold electrodes in top-contact field-effect transistors (FETs) via the transfer of chemically pre-modified electrodes. The source and drain Au electrodes of the molybdenum disulfide (MoS2) FETs are functionalized with thiolated molecules possessing different dipole moments. While the modification of the electrodes with electron-donating molecules yields a marked improvement of device performance, the asymmetric functionalization of the source and drain electrodes with different molecules with opposed dipole moment enables the fabrication of a high-performance Schottky diode with a rectification ratio of ≈10^3. This unprecedented strategy to tune the charge injection in top-contact MoS2 FETs is of general applicability for the fabrication of high-performance (opto-)electronic devices, in which asymmetric charge injection is required, enabling tailoring of the device characteristics on demand

Nonclassical Growth of Atomically Flat Two‐Dimensional Organic Single Crystals on a Liquid Surface through Fusion

Abstract Organic single crystals with low defect density are key functional materials for next‐generation electronics. Classical crystallization commonly results in a high density of molecular steps, which are defects that can trap charge carriers and reduce the mobility of organic semiconductors. Herein, a novel nonclassical crystallization mechanism involving nucleation, fusion, and growth is designed. The introduction of the fusion stage changes the crystal growth mode from three‐dimensional island growth to two‐dimensional layer‐by‐layer growth and leads to large‐area two‐dimensional molecular crystals with almost no molecular steps. Therefore, the average mobility is observed to improve from 1.26 to 2.07 cm2 V−1 s−1. The nonclassical crystallization mechanism paves the way for atomically flat single crystals to probe the intrinsic optoelectronic properties of organic semiconductors

Bandgap Engineering of an Aryl-Fused Tetrathianaphthalene for Visible-Blind Organic Field-Effect Transistors

10.3389/fchem.2021.698246Frontiers in Chemistry969824

Structural Characterization of a Novel Glucan from <i>Achatina fulica</i> and Its Antioxidant Activity

A novel glucan designated AFPS-IB was purified from <i>Achatina fulica</i> (China white jade snail) by anion-exchange and gel-permeation chromatography. Chemical composition analysis indicated AFPS-IB was composed of glucose, fucose, rhamnose, mannose, and galactose in a molar ratio of 189:2:1:1:2 and with an average molecular weight of 128 kDa. Its structural characteristics were investigated by Fourier transform infrared spectroscopy (FTIR), high performance liquid chromatography (HPLC), gas chromatography mass spectrometry (GC–MS), methylation analysis, nuclear magnetic resonance (NMR) spectroscopy (¹H,¹³C, H–H COSY, HSQC, TOCSY, and NOESY), and atomic force microscopy (AFM). The glucan mainly consisted of a backbone of repeating (1→4)-α-d-glucose residues with (1→6)-β-d glucosyl branches at random points on the backbone glucose. Antioxidant studies revealed AFPS-IB showed significant DPPH (2,2-diphenyl-1-picrylhydrazyl) radical, superoxide anion (O₂^–) scavenging activities and high reduction potential. This study suggested that AFPS-IB could be a new source of dietary antioxidants

Pyropia yezoensis genome reveals diverse mechanisms of carbon acquisition in the intertidal environment

The nori producing seaweed Pyropia yezoensis has heteromorphic generations that occupy distinct habitats. Here, via genome assembly, transcriptome analysis, and 13 C isotope labeling, the authors show the interplay between inorganic carbon availability and life cycle evolution in the intertidal environment