Jinyu Liu

Occurrence of butyltin compounds in the waters of selected lakes, rivers and coastal environments from China

The presence of butyltin compounds was investigated for the first time in selected lakes, rivers and coastal environments of China. Aqueous samples were pretreated by the technique of headspace solid phase micro-extraction after hydride generation with sodium tetrahydroborate (NaBH4). Quantitative measurement of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) concentrations were accomplished by capillary gas chromatography with flame photometric detector using quartz surface-induced luminescence. Experimental data demonstrated the widespread occurrence of butyltin compounds in the Chinese aquatic environment. In some locations, the concentrations of TBT were higher than the acute and chronic toxicity threshold of sensitive fresh water or marine organisms. Although DBT and MBT (which mainly come from the degradation of TBT), are less toxic, their occurrence can still affect the ecosystem over a long time frame.

Electrochemical fabrication of single-crystalline and polycrystalline Au nanowires : the influence of deposition parameters

We report the electrochemical growth of gold nanowires with controlled dimensions and crystallinity. By systematically varying the deposition conditions, both polycrystalline and single-crystalline wires with diameters between 20 and 100 nm are successfully synthesized in etched ion-track membranes. The nanowires are characterized using scanning electron microscopy, high resolution transmission electron microscopy, scanning tunnelling microscopy and x-ray diffraction. The influence of the deposition parameters, especially those of the electrolyte, on the nanowire structure is investigated. Gold sulfite electrolytes lead to polycrystalline structure at the temperatures and voltages employed. In contrast, gold cyanide solution favours the growth of single crystals at temperatures between 50 and 65 °C under both direct current and reverse pulse current deposition conditions. The single-crystalline wires possess a [110] preferred orientation.

Enhancing field-effect mobility and maintaining solid-state emission by incorporating 2,6-diphenyl substitution to 9,10-bis(phenylethynyl)anthracene

The development of optical and electrical organic semiconductors is crucial for the construction of integrated optoelectronic devices. Herein, a new anthracene derivative, 2,6-diphenyl-9,10-bis(phenylethynyl)anthracene (DP-BPEA), was designed and synthesized by enlarging the π-conjugation of 9,10-bis(phenylethynyl)anthracene (BPEA) via 2,6-diphenyl substitution. Compared with the parent BPEA molecule, an improved field-effect mobility of 1.37 cm2 V−1 s−1 with a comparable solid fluorescence efficiency of 32% is obtained for DP-BPEA, suggesting its potential applications in integrated optoelectronic devices.

Copolymer dielectrics with balanced chain-packing density and surface polarity for high-performance flexible organic electronics

The ever-increasing demand for flexible electronics calls for the development of low-voltage and high-mobility organic thin-film transistors (OTFTs) that can be integrated into emerging display and labeling technologies. Polymer dielectrics with comprehensive and balanced dielectric properties (i.e., a good balance between their insulating characteristics and compatibility with organic semiconductors) are considered particularly important for this end. Here, we introduce a simple but highly efficient strategy to realize this target by using a new type of copolymer as dielectrics. Benefiting from both high chain packing density guaranteeing dielectric properties and surface polarity optimizing molecular packing of organic semiconductors, this rationally designed copolymer dielectric endows flexible OTFTs with high mobility (5.6u2009cm2u2009V−1u2009s−1), low operating voltage (3u2009V) and outstanding stability. Further, their applicability in integrated circuits is verified. The excellent device performance shows exciting prospects of this molecular-scale engineered copolymer for the realization of plastic high-performance integratedxa0electronics.Developing large-scale flexible display technologies calls for new gate dielectric materials balancing the insulating property and molecular packing of organic semiconductors. Ji et al. synthesize a dielectric copolymer contributing with charge mobility of 5u2009cm2u2009V−1u2009s−1 and low operating voltage of 3u2009V.

Negative transconductance in multi-layer organic thin-film transistors

Negative transconductance (NTC) refers to the phenomenon of the N-shape transfer characteristic appearing with a current peak and valley. It has been extensively studied in the past few decades due to its applications in logic and memory devices. Here, we observe unique antibipolar transfer characteristics and NTC behavior in multi-layer 2,6-diphenyl anthracene organic thin-film transistors grown on h-BN, which is due to the vertical potential barrier between the charge accumulation region near the substrate and the neutral bulk region under the contacts. The applied extrinsic electric field could effectively modulate the barrier height, resulting in a competition for charge carrier transport between lateral and vertical directions. Based on the NTC and antibipolar properties, a frequency doubler has been fabricated on a single transistor, which provides a new building block for organic logic circuits.

Organic‐Single‐Crystal Vertical Field‐Effect Transistors and Phototransistors

Organic vertical field-effect transistors (VFETs) have attracted significant attention over the past years due to their unique characteristics of high output currents, low operation voltages, high working frequency, and promising high-density integration for circuits. However, most currently reported VFETs demonstrate poor performance, e.g., with low on/off ratio and current density. Here, the first organic-single-crystal vertical field-effect transistors (SC-VFETs) and phototransistors are constructed from 2,6-diphenyl anthracene (DPA) through a modified method. The devices exhibit high on/off ratio of 106 and a high current density of 100 mA cm-2 under a small voltage of -5 V, which are proved to be one of the best performances for organic VFETs. Furthermore, superior photoresponse performance with photoresponsivity of 110 A W-1 and detectivity of 1013 Jones is obtained under light illumination for vertical phototransistors. These results confirm the control of the intrinsic Schottky barrier height at the graphene-DPA junction along with good interfacial contact effectively suppressing the dark current to realize a large on/off ratio and high light detectivity. This vertical integration of graphene with organic single crystals via simple, effective fabrication processes opens up new opportunities to realize high-performance integrated organic vertical electronic and optoelectronic devices.