https://cyberleninka.org/article/n/1018032.pdf

Polymer nanotechnology: Nanocomposites

An overview of the recent developments in polylactide (PLA) research.

Interpretation of X-ray Powder Diffraction Patterns . By H. Lipson and H. Steeple. Pp. viii + 335 + 3 plates. (Mac-millan: London; St Martins Press: New York, May 1970.) £4.

X-Ray Diffraction

The authors would like to thank M. Chabinyc, H. Ade, B. Collins, R. Noriega, K. Vandewal, and D. Duong for fruitful discussions in the preparation of this review. Stanford Synchrotron Radiation Lightsource (SSRL) is a national user facility operated by Stanford University on behalf of the U.S. Department of Energy, Office of Basic Energy Sciences. This publication was partially supported by the Center for Advanced Molecular Photovoltaics (Award No. KUS-C1-015-21), made by King Abdullah University of Science and Technology (KAUST).

Quantitative determination of organic semiconductor microstructure from the molecular to device scale.

Nanographenes, or extended polycyclic aromatic hydrocarbons, have been attracting renewed and more widespread attention since the first experimental demonstration of graphene in 2004. However, the atomically precise fabrication of nanographenes has thus far been achieved only through synthetic organic chemistry. The precise synthesis of quasi-zero-dimensional nanographenes, i.e. graphene molecules, has witnessed rapid developments over the past few years, and these developments can be summarized in four categories: (1) non-conventional methods, (2) structures incorporating seven- or eight-membered rings, (3) selective heteroatom doping, and (4) direct edge functionalization. On the other hand, one-dimensional extension of the graphene molecules leads to the formation of graphene nanoribbons (GNRs) with high aspect ratios. The synthesis of structurally well-defined GNRs has been achieved by extending nanographene synthesis to longitudinally extended polymeric systems. Access to GNRs thus becomes possible through the solution-mediated or surface-assisted cyclodehydrogenation, or “graphitization,” of tailor-made polyphenylene precursors. In this review, we describe recent progress in the “bottom-up” chemical syntheses of structurally well-defined nanographenes, namely graphene molecules and GNRs.

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New advances in nanographene chemistry

To tilt or not to tilt: The crystal structure for bulk P3HT (phase I) was determined by "multi-technique crystallography", which combines X-ray diffraction, solid-state NMR spectroscopy, and DFT calculations. The results showed that this semiconducting polymer crystallizes in the monoclinic space group P2(1)/c with nontilted π-stacks at a distance of 3.9 A (see picture).

A strategy for revealing the packing in semicrystalline π-conjugated polymers: crystal structure of bulk poly-3-hexyl-thiophene (P3HT).

Probing the role of the first monolayer in the evolution of the film polymer microstructure is essential for the fundamental understanding of the charge carrier transport in polymeric field-effect ...

Microstructure evolution and device performance in solution-processed polymeric field-effect transistors: the key role of the first monolayer.

In organic field-effect transistors (OFETs) the electrical characteristics of polymeric semiconducting materials suffer from the presence of structural/morphological defects and grain boundaries as well as amorphous domains within the film, hindering an efficient transport of charges. To improve the percolation of charges we blend a regioregular poly(3-hexylthiophene) (P3HT) with newly designed N = 18 armchair graphene nanoribbons (GNRs). The latter, prepared by a bottom-up solution synthesis, are expected to form solid aggregates which cannot be easily interfaced with metallic electrodes, limiting charge injection at metal–semiconductor interfaces, and are characterized by a finite size, thus by grain boundaries, which negatively affect the charge transport within the film. Both P3HT and GNRs are soluble/dispersible in organic solvents, enabling the use of a single step co-deposition process. The resulting OFETs show a three-fold increase in the charge carrier mobilities in blend films, when compared to pure P3HT devices. This behavior can be ascribed to GNRs, and aggregates thereof, facilitating the transport of the charges within the conduction channel by connecting the domains of the semiconductor film. The electronic characteristics of the devices such as the Ion/Ioff ratio are not affected by the addition of GNRs at different loads. Studies of the electrical characteristics under illumination for potential use of our blend films as organic phototransistors (OPTs) reveal a tunable photoresponse. Therefore, our strategy offers a new method towards the enhancement of the performance of OFETs, and holds potential for technological applications in (opto)electronics.

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Adam Kiersnowski

Papers

A strategy for revealing the packing in semicrystalline π-conjugated polymers: crystal structure of bulk poly-3-hexyl-thiophene (P3HT).

Microstructure evolution and device performance in solution-processed polymeric field-effect transistors: the key role of the first monolayer.

Graphene nanoribbon blends with P3HT for organic electronics.

Polymer-layered silicate nanocomposites based on poly(ε-caprolactone)

Synthesis and structure of poly(ε-caprolactone)/synthetic montmorillonite nano-intercalates