Growth of Highly Oriented Ultrathin Crystalline Organic Microstripes: Effect of Alkyl Chain Length

The growth of organic semiconductor with controllable morphology is a crucial issue for achieving high-performance devices. Here we present the systematic study of the effect of the alkyl chain attached to the functional entity on controlling the growth of oriented microcrystals by dip-coating. Alkylated DTBDT-based molecules with variable chain lengths from n-butyl to n-dodecyl formed into one-dimensional micro- or nanostripe crystals at different pulling speeds. The alignment and ordering are significantly varied with alkyl chain length, as is the transistor performance. Highly uniform oriented and higher-molecular-order crystalline stripes with improved field-effect mobility can be achieved with an alkyl-chain length of around 6. We attribute this effect to the alkyl-chain-length-dependent packing, solubility, and self-assembly behavior.

[Correlative factors related to the density of Meriones unguiculatus in the Meriones unguiculatus plague foci of Hebei province, 2001-2013]

OBJECTIVE

To explore the yearly, monthly and habitat-related distribution and their relations with Meriones unguiculatus density in the Hebei Meriones unguiculatus plague foci, from 2001 to 2013.

METHODS

Data related to Meriones unguiculatus was gathered through the monitoring programs set up at the national and provincial Meriones unguiculatus plague foci in Hebei province, from 2001 to 2013. According to the yearly density of Meriones unguiculatus, criteria set for the three groups under study, were as follows:'high-risk group'-when the rodent density was≥1.00 under rodents/hm(2),'warning group'-when the rodents/hm(2)>rodent density> 0.20,'standard group'-when rodents/hm(2) rodent density≤0.20 rodents/hm(2). Differences of habitats and monthly distribution among the three groups were compared, under the Kruskal-Wallis H rank sum test while their relations were under the multiple correspondence analysis.

RESULTS

The Meriones unguiculatus densities were higher than 1.00 rodents/hm(2), far above the set national standards, in the monitoring area, between 2001 and 2005. From 2005, though the rodent densities began to decrease, however, figures from 2008 to 2013 were still among 0.20 to 1.00 rodents/hm(2). The distribution of habitats in the three groups showed that the Meriones unguiculatus densities were all different in habitats and the difference was statistically significant (P<0.05). The highest median densities were all in the arable land, with maximum value of high-risk group appeared the highest (20.50 rodents/hm(2)) in the wasteland. Monthly distribution showed that the Meriones unguiculatus densities were different and the difference was statistically significant (P<0.05) in the high-risk and standard groups but not statistically significant in the warning group. Data from the multiple correspondence analysis showed that there was a strong aggregation among wasteland, in April and June, while the warning group was associated with weather in July and the arable land.

CONCLUSIONS

When the density became higher than 1.00 rodents/hm(2), the risk on animal plague increased in Hebei Meriones unguiculatus plague foci. Based on the distribution of Meriones unguiculatus, programs should be set to monitor the rodent in arable land and wasteland, in April and June, to reduce the prevalence of animals plague.

Fully Integrated Organic Nanocrystal Diode as High Performance Room Temperature NO2 Sensor

Organic diodes consisting of molecular nano-pyramid structures sandwiched between metal and strained nano-membrane electrodes are created. The robust and smooth contacts provided by self-curled metal layers render the molecular nano-pyramids efficent channels for detecting nitrogen dioxide airflow.

Large-area perovskite nanowire arrays fabricated by large-scale roll-to-roll micro-gravure printing and doctor blading

Organic-inorganic hybrid halide perovskite nanowires (PNWs) show great potential applications in electronic and optoelectronic devices such as solar cells, field-effect transistors and photodetectors. It is very meaningful to fabricate ordered, large-area PNW arrays and greatly accelerate their applications and commercialization in electronic and optoelectronic devices. Herein, highly oriented and ultra-long methylammonium lead iodide (CH3NH3PbI3) PNW array thin films were fabricated by large-scale roll-to-roll (R2R) micro-gravure printing and doctor blading in ambient environments (humility ∼45%, temperature ∼28 °C), which produced PNW lengths as long as 15 mm. Furthermore, photodetectors based on these PNWs were successfully fabricated on both silicon oxide (SiO2) and flexible polyethylene terephthalate (PET) substrates and showed moderate performance. This study provides low-cost, large-scale techniques to fabricate large-area PNW arrays with great potential applications in flexible electronic and optoelectronic devices.

Organic thin film transistors with novel photosensitive polyurethane as dielectric layer

The solution-processable photosensitive polyurethane dielectric film is a promising candidate for the exploration of organic thin-film transistors (OTFTs).