The Influence of Conjugated Polymer Side Chain Manipulation on the Efficiency and Stability of Polymer Solar Cells.

The stability of polymer solar cells (PSCs) can be influenced by the introduction of particular moieties on the conjugated polymer side chains. In this study, two series of donor-acceptor copolymers, based on bis(thienyl)dialkoxybenzene donor and benzo[][1,2,5]thiadiazole (BT) or thiazolo[5,4-]thiazole (TzTz) acceptor units, were selected toward effective device scalability by roll-coating. The influence of the partial exchange (5% or 10%) of the solubilizing 2-hexyldecyloxy by alternative 2-phenylethoxy groups on efficiency and stability was investigated.

Homodiselenacalix[4]arenes: Molecules with Unique Channelled Crystal Structures.

A synthetic route towards homodiselenacalix[4]arene macrocycles is presented, based on the dynamic covalent chemistry of diselenides. The calixarene inner rim is decorated with either alkoxy or tert-butyl ester groups. Single-crystal X-ray analysis of two THF solvates with methoxy and ethoxy substituents reveals the high similarity of their molecular structures and alterations on the supramolecular level.

PPV Polymerization through the Gilch Route: Diradical Character of Monomers.

Despite various studies on the polymerization of poly(p-phenylene vinylene) (PPV) through different precursor routes, detailed mechanistic knowledge on the individual reaction steps and intermediates is still incomplete. The present study aims to gain more insight into the radical polymerization of PPV through the Gilch route. The initial steps of the polymerization involve the formation of a p-quinodimethane intermediate, which spontaneously self-initiates through a dimerization process leading to the formation of diradical species; chain propagation ensues on both sides of the diradical or chain termination occurs by the formation of side products, such as [2.

Synthesis of sequence-defined acrylate oligomers photo-induced copper-mediated radical monomer insertions.

Photo-induced copper-mediated radical polymerization is used to synthesize monodisperse sequence defined acrylate oligomers consecutive single unit monomer insertion reactions and intermediate purification of the compounds by column chromatography or preparative recycling size exclusion chromatography. Monomer conversions are followed during reaction by means of infrared spectroscopy. When reaction conditions are chosen carefully and any residues from chlorinated solvents are avoided, 100% pure Br end capped sequence defined oligomers are obtained, demonstrating the convenience and power of photo-induced copper mediated radical insertion for establishing sequence control.

Improved Livingness and Control over Branching in RAFT Polymerization of Acrylates: Could Microflow Synthesis Make the Difference?

The superior capabilities of structured microreactors over batch reactors are demonstrated for reversible addition-fragmentation chain transfer (RAFT) solution polymerization of n-butyl acrylate with the aid of simulations, explicitly accounting for the chain length distribution of all macrospecies types. Since perfect isothermicity can be established in a microreactor, less side products due to backbiting and β-scission are formed compared to the batch operation in which ineffective heat removal leads to an undesirable temperature spike. For a given RAFT chain transfer agent (CTA), additional microstructural control results under microflow conditions by optimizing the reaction temperature, lowering the dilution degree, or decreasing the initial molar ratio of monomer to RAFT CTA.

Continuous Flow Polymer Synthesis toward Reproducible Large-Scale Production for Efficient Bulk Heterojunction Organic Solar Cells.

Organic photovoltaics (OPV) have attracted great interest as a solar cell technology with appealing mechanical, aesthetical, and economies-of-scale features. To drive OPV toward economic viability, low-cost, large-scale module production has to be realized in combination with increased top-quality material availability and minimal batch-to-batch variation. To this extent, continuous flow chemistry can serve as a powerful tool.

Solvent Effects on kp in Organic Media?: Statement to the Response.

A recent response on a publication from our team investigating solvent effects on propagation rate coefficients is commented. Among other issues, we point to the fact that the response interprets only a subset of the data provided in our original contribution.

Quinoxaline-Based Cyclo(oligophenylenes).

A series of fully conjugated quinoxaline-based oligophenylene macrocycles is synthesized by Ni(0)-mediated Yamamoto-type diaryl homocoupling of (fluorinated) 2,3-bis(4'-bromophenyl)quinoxaline precursors. Cyclotrimers and cyclotetramers are obtained as the dominant reaction products. The cyclooligomers are fully characterized, including single-crystal X-ray structures, and their optoelectronic properties are analyzed with respect to possible applications in host-guest chemistry and organic electronics.

Organic phototransistors using poly(3-hexylthiophene) nanofibres.

Here we report the fabrication of nanofibre-based organic phototransistors (OPTs) using preformed poly(3-hexylthiophene) (P3HT) nanofibres. OPT performance is analysed based on two important parameters: photoresponsivity R and photosensitivity P. Before testing the devices as OPTs, the normal organic field-effect transistor (OFET) operation is characterized, revealing a surface-coverage-dependent performance.

Direct arylation as a versatile tool towards thiazolo[5,4-d]thiazole-based semiconducting materials.

A series of thiazolo[5,4-d]thiazole-based small molecule organic optoelectronic materials is synthesized via a straightforward microwave-activated Pd-catalyzed C-H arylation protocol. The procedure allows us to obtain extended 2,5-dithienylthiazolo[5,4-d]thiazole chromophores with tailor-made energy levels and absorption patterns, depending on the introduced (het)aryl moieties and the molecular (a)symmetry, by shortened sequences without organometallic intermediates. The synthesized materials can be applied as either electron donor or electron acceptor light-harvesting materials in molecular bulk heterojunction organic solar cells.

Synthesis of sequence controlled acrylate oligomers via consecutive RAFT monomer additions.

An effective procedure to synthesize sequence controlled oligoacrylates with up to four monomer insertions via the RAFT technique is presented. Two different sets of oligomers with a preferred monomer order were synthesized. Recycling SEC allowed for facile and automated purification of the monodisperse sequence-controlled materials.

Controlled synthesis of ultrathin ZnO nanowires using micellar gold nanoparticles as catalyst templates.

We demonstrate a simple and effective approach to control the diameter of ultrathin ZnO nanowires with high aspect ratios and high densities over large areas. Diblock copolymer-based nanoparticle arrays exhibiting a high degree of hexagonal order and offering easy control of particle size (typically 1-10 nm) and interparticle spacing (25-150 nm) are utilized as nanocatalysts for the subsequent growth of semiconductor nanowires. The as-grown ZnO nanowires exhibit a single crystal hexagonal wurtzite structure and grow along the [0002] direction.

Combined experimental-theoretical NMR study on 2,5-bis(5-aryl-3-hexylthiophen-2-yl)-thiazolo[5,4-d]thiazole derivatives for printable electronics.

Four 2,5-bis(5-aryl-3-hexylthiophen-2-yl)thiazolo[5,4-d]thiazole derivatives have been synthesized and thoroughly characterized. The extended aromatic core of the molecules was designed to enhance the charge transport characteristics, and solubilizing hexyl side chains were introduced on the thiophene subunits to enable possible integration of these semiconducting small molecules in printable electronics. Complete elucidation of the chemical structures by detailed one-dimensional/two-dimensional NMR spectroscopy is described, providing interesting input for chemical shift prediction software as well, because limited experimental data on these types of compounds are currently available.