Effects of the Donor Unit on the Formation of Hybrid Layers of Donor-Acceptor Copolymers with Silver Nanoparticles

Donor-acceptor (D-A) copolymers containing perylene-3,4,9,10-tetracarboxydiimide (PDI) electron-acceptor (A) units belonging to n-type semiconductors are of interest due to their many potential applications in photonics, particularly for electron-transporting layers in all-polymeric or perovskite solar cells. Combining D-A copolymers and silver nanoparticles (Ag-NPs) can further improve material properties and device performances. Hybrid layers of D-A copolymers containing PDI units and different electron-donor (D) units (9-(2-ethylhexyl)carbazole or 9,9-dioctylfluorene) with Ag-NPs were prepared electrochemically during the reduction of pristine copolymer layers. The formation of hybrid layers with Ag-NP coverage was monitored by in-situ measurement of absorption spectra. The Ag-NP coverage of up to 41% was higher in hybrid layers made of copolymer with 9-(2-ethylhexyl)carbazole D units than in those made of copolymer with 9,9-dioctylfluorene D units. The pristine and hybrid copolymer layers were characterized by scanning electron microscopy and X-ray photoelectron spectroscopy, which proved the formation of hybrid layers with stable Ag-NPs in the metallic state with average diameters <70 nm. The influence of D units on Ag-NP diameters and coverage was revealed

Hybrid Layers of Donor-Acceptor Copolymers with Homogenous Silver Nanoparticle Coverage for Photonic Applications

Hybrid layers of donor-acceptor (D-A) copolymers containing N,N′-dialkylperylene-3,4,9,10-tetracarboxydiimide electron-acceptor units covered with silver nanoparticles (Ag-NPs) were prepared by electrochemical doping of pristine layers during reduction processes. In situ optical absorption spectra of the layers were recorded during the formation of Ag-NP coverage. The hybrid layers were characterized by absorption spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDX). In the absorption spectra of the hybrid layers, a surface plasmon band characteristic of Ag-NPs appeared. Significant improvements in light absorption due to the plasmonic effects of Ag NPs were observed. Stable Ag-NPs with an average diameter of 41–63 nm were formed on the surface, as proven by SEM and XPS. The Ag-NP coverage and size depended on the hybrid layer preparation conditions and on the copolymer composition. The metallic character of the Ag-NPs was proven by XPS. The location in the surface layer was further confirmed by EDX analysis. To the best of our knowledge, this is the first report on such hybrid layers having the potential for a variety of photonic and electronic applications

Creating Patterned Conjugated Polymer Images Using Water-Compatible Reactive Inkjet Printing

The fabrication of patterned conjugated polymer images on solid substrates has gained significant attention recently. Office inkjet printers can be used to generate flexible designs of functional materials on substrates on a large scale and in an inexpensive manner. Although creating patterns of conjugated polymers on paper using common office inkjet printers has been reported, only a few examples exist, such as polyaniline (PANI) and poly­(3,4-ethylenedioxythiophene) (PEDOT), because only water-compatible inks can be utilized. Herein, we describe the production of poly­(phenylenevinylene) (PPV) patterns on paper by employing a reactive inkjet printing (RIJ) method. In this process, printing of a hydrophilic terephthaldehyde, bis­(triphenylphosphonium salt) and potassium t-butoxide using a common office inkjet printer leads to formation PPV patterns as a consequence of an in situ Wittig reaction. In addition, microarrayed PPV patterns are also readily generated on solid substrates, such as glass and PDMS, when a piezoelectric dispenser system is employed. The in situ prepared PPV was found to be insoluble in water and chloroform. As a result, unreacted excess reagents and byproducts can be efficiently removed by washing with these solvents

Sulfonated Copper Phthalocyanine/Sulfonated Polysulfone Composite Membrane for Ionic Polymer Actuators with High Power Density and Fast Response Time

Ionic polymer composite membranes based on sulfonated poly­(arylene ether sulfone) (SPAES) and copper­(II) phthalocyanine tetrasulfonic acid (CuPCSA) are assembled into bending ionic polymer actuators. CuPCSA is an organic filler with very high sulfonation degree (IEC = 4.5 mmol H⁺/g) that can be homogeneously dispersed on the molecular scale into the SPAES membrane, probably due to its good dispersibility in SPAES-containing solutions. SPAES/CuPCSA actuators exhibit larger ion conductivity (102 mS cm^–1), tensile modulus (208 MPa), strength (101 MPa), and strain (1.21%), exceptionally faster response to electrical stimuli, and larger mechanical power density (3028 W m^–3) than ever reported for ion-conducting polymer actuators. This outstanding actuation performance of SPAES/CuPCSA composite membrane actuators makes them attractive for next-generation transducers with high power density, which are currently developed, e.g., for underwater propulsion and endoscopic surgery

High β‐phase Poly(vinylidene fluoride) Using a Thermally Decomposable Molecular Splint

Abstract An additive, 1,4‐butadiene sulfone (BDS), which generates H2SO3 by in situ thermal retro‐Diels‐Alder decompositions, is used for preparing high β‐phase polyvinylidene fluoride (PVDF) films. Because of preferential multiple non‐covalent interactions of H2SO3 with all‐trans configuration of PVDF, β‐phase PVDF is spontaneously induced without mechanical drawing and/or extensive thermal annealing process. PVDF films cast from PVDF/BDS/water solutions exhibit high β‐phase content (fβ = 95%) when the BDS concentration is only cBDS = 1.0 wt%, which is confirmed by polarized optical microscopy (POM), SEM, Fourier transform infrared spectroscopy (FT‐IR), differential scan calorimetry (DSC), and 2D grazing incidence wide‐angle X‐ray scattering (GIWAXS). Because of the high β‐phase content, PVDF films prepared by using BDS exhibit excellent ferroelectric and piezoelectric properties (Ec = 50 MV/m, Pr = 5 µC/cm2, and d33 = ≈‐25 pm/V). Furthermore, a triboelectric nanogenerator (TENG) developed with high β‐phase PVDF film exhibits enhanced performance as 2.5 times higher than neat PVDF film in output charge density, allowing reliable operation of conventional electronic devices

Potential of Biosynthesized Silver Nanoparticles as Nanocatalyst for Enhanced Degradation of Cellulose by Cellulase

Silver nanoparticles (AgNPs) as a result of their excellent optical and electronic properties are promising catalytic materials for various applications. In this study, we demonstrate a novel approach for enhanced degradation of cellulose using biosynthesized AgNPs in an enzyme catalyzed reaction of cellulose hydrolysis by cellulase. AgNPs were synthesized through reduction of silver nitrate by extracts of five medicinal plants (Mentha arvensis var. piperascens, Buddleja officinalis Maximowicz, Epimedium koreanum Nakai, Artemisia messer-schmidtiana Besser, and Magnolia kobus). An increase of around twofold in reducing sugar formation confirmed the catalytic activity of AgNPs as nanocatalyst. The present study suggests that immobilization of the enzyme onto the surface of the AgNPs can be useful strategy for enhanced degradation of cellulose, which can be utilized for diverse industrial applications

A new rigid planar low band gap PTTDPP-DT-DTT polymer for organic transistors and performance improvement through the use of a binary solvent system

We report the synthesis of a new low band gap planar polymer of poly(2,5-bis(2-decyltetradecyl)-3-(5-(dithieno[3,2-b:2&apos;,3&apos;-d]thiophen-2-yl)thieno[3,2-b]thiophen-2-y1)-6-(thieno[3,2-b]thiophen-2-y1)-2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione) (PTTDPP-DT-DTT) for use in organic thin film transistors (OTFTs). The polymer backbone is highly planar and well-conjugated, facilitating interchain stacking. The PTTDPP-DT-DTT-based OTFTs were fabricated and carrier mobilities were improved by using a binary solvent system: chloroform (CF):toluene (Tol), CF:chlorobenzene (CB), and CF:o-dichlorobenzene (DCB). The addition of higher boiling point solvents promoted film crystallinity with more edge-on orientations. Thus, the use of CF:DCB yielded the highest carrier mobility obtained among the devices tested. Thermal annealing further enhanced the mobility of the CF:DCB device. Atomic force microscopy images disclosed the most fibrous feature in the thermally annealed polymer film cast from CF:DCB solution. This work highlights that both the proper selection of a binary solvent and thermal annealing can manage film morphology of rigid planar conjugated polymer semiconductors effectively for high-performance OTFTs

Low Temperature Thermochromic Polydiacetylenes: Design, Colorimetric Properties, and Nanofiber Formation

Owing to their stimulus responsive color changing properties, polydiacetylenes (PDAs) have been extensively investigated as colorimetric sensors. Thermochromic properties of PDAs have been the central focus of a number of investigations that were aimed not only at gaining a fundamental understanding of the physical basis of the color change but also at developing practical applications as temperature sensors. The thermochromic transition temperature of a PDA polymer is closely related to the melting point of the corresponding diacetylene (DA) monomer. In addition, the majority of PDAs described to date undergo a blue-to-red color change above room temperature because PDAs are generally derived from DA monomers that have melting points above room temperature. In the current study, we developed a series of low temperature colorimetric PDAs that were designed based on the reasoning that removal of the sources for strong headgroup interactions would lower the melting points of the corresponding DA monomers. This strategy was used to design and fabrication of PDA sensors that display color transitions in the range of 5–30 °C. Moreover, the thermochromic transition temperatures of the PDAs were found to decrease by ca. 10 °C when the alkyl chain length in the DA monomer is truncated by two methylene units. The results of FTIR and Raman spectroscopic analyses suggest that the PDA alkyl chain adopts an <i>all-trans</i> conformation in the blue-phase and some <i>gauche</i> forms exist in the alkyl chain in the red-phase PDA. Finally, the new PDAs are stable up to 300 °C, and their processable nature enables them to be fabricated in nanofiber forms by employing an anodized aluminum oxide (AAO) membrane as a template

Cross-Stacked Single-Crystal Organic Nanowire p–n Nanojunction Arrays by Nanotransfer Printing

We fabricated cross-stacked organic p–n nanojunction arrays made of single-crystal 6,13-bis­(triisopropylsilylethynyl) pentacene (TIPS-PEN) and fullerene (C₆₀) nanowires as p-type and n-type semiconductors, respectively, by using a nanotransfer printing technique. Single-crystal C₆₀ nanowires were synthesized inside nanoscale channels of a mold and directly transferred onto a desired position of a flexible substrate by a lubricant liquid layer. In the consecutive printing process, single-crystal TIPS-PEN nanowires were grown in the same way and then perpendicularly aligned and placed onto the C₆₀ nanowire arrays, resulting in a cross-stacked single-crystal organic p–n nanojunction array. The cross-stacked single-crystal TIPS-PEN/C₆₀ nanowire p–n nanojunction devices show rectifying behavior with on/off ratio of ∼13 as well as photodiode characteristic with photogain of ∼2 under a light intensity of 12.2 mW/cm². Our study provides a facile, solution-processed approach to fabricate a large-area array of organic crystal nanojunction devices in a desired arrangement for future nanoscale electronics