Two Is Better than One: How the Addition of Multiple Biodegradable Polymers Can Improve Organic Thin-Film Transistor Performance.

Developing sustainable electronics requires using materials that are either recyclable or biodegradable, without compromising on electrical performance. Here, we introduce a solution-processed biodegradable polymer blend consisting of a diketopyrrolopyrrole-based semiconducting polymer (DPP2T) and different mixtures of two biodegradable polymers, polycaprolactone (PCL) and polylactic acid (PLA). We find that controlling the ratio of components enables a reduction in semiconductor polymer loading (∼70:80% reduction) while maintaining or improving field-effect transistor performance.

High Throughput Characterization of Organic Thin Film Transistors.

Automation is vital to accelerating research. In recent years, the application of self-driving labs to materials discovery and device optimization has highlighted many benefits and challenges inherent to these new technologies. Successful automated workflows offer tangible benefits to fundamental science and industrial scale-up by significantly increasing productivity and reproducibility all while enabling entirely new types of experiments.

Identification of D-arabinan-degrading enzymes in mycobacteria.

Bacterial cell growth and division require the coordinated action of enzymes that synthesize and degrade cell wall polymers. Here, we identify enzymes that cleave the D-arabinan core of arabinogalactan, an unusual component of the cell wall of Mycobacterium tuberculosis and other mycobacteria. We screened 14 human gut-derived Bacteroidetes for arabinogalactan-degrading activities and identified four families of glycoside hydrolases with activity against the D-arabinan or D-galactan components of arabinogalactan.

Dopant-Stabilized Assembly of Poly(3-hexylthiophene).

Polymer self-assembly is a powerful approach for forming nanostructures for solution-phase applications. However, polymer semiconductor assembly has primarily been driven by solvent interactions. Here, we report poly(3-hexythiophene) homopolymer assembly driven and stabilized by oxidative doping with iron (III) -toluenesulfonate in benzonitrile.

Poly(ionic liquid) Gating Materials for High-Performance Organic Thin-Film Transistors: The Role of Block Copolymer Self-Assembly at the Semiconductor Interface.

The widespread realization of wearable electronics requires printable active materials capable of operating at low voltages. Polymerized ionic liquid (PIL) block copolymers exhibit a thickness-independent double-layer capacitance that makes them a promising gating medium for the development of organic thin-film transistors (OTFTs) with low operating voltages and high switching speed. PIL block copolymer structure and self-assembly can influence ion conductivity and the resulting OTFT performance.

Thermoconformational Behavior of Cellulose Nanofiber Films as a Device Substrate and Their Superior Flexibility and Durability to Glass.

The design and high-throughput manufacturing of thin renewable energy devices with high structural and atomic configurational stability are crucial for the fabrication of green electronics. Yet, this concept is still in its infancy. In this work, we report the extraordinary durability of thin molecular interlayered organic flexible energy devices based on chemically tuned cellulose nanofiber transparent films that outperform glass by decreasing the substrate weight by 50%.

High-Throughput Screening of Antisolvents for the Deposition of High-Quality Perovskite Thin Films.

One-step solution deposition of high-quality perovskite thin films relies heavily on a small number of antisolvents. Here, we design a simple minimum volume colorimetric solution assay to screen over 100 different solvents. We correctly identify 14 previously reported antisolvents and predict 20 novel candidates.

Oxidation promoted self-assembly of π-conjugated polymers.

Self-assembly is an attractive strategy for organizing molecules into ordered structures that can span multiple length scales. Crystallization Driven Self-Assembly (CDSA) involves a block copolymer with a crystallizable core-forming block and an amorphous corona-forming block that aggregate into micelles with a crystalline core in solvents that are selective for the corona block. CDSA requires core- and corona-forming blocks with very different solubilities.

Helicoidal Patterning of Gold Nanorods by Phase Separation in Mixed Polymer Brushes.

The spatial distribution of polymer ligands on the surface of nanoparticles (NPs) is of great importance because it determines their interactions with each other and with the surrounding environment. Phase separation in mixtures of polymer brushes has been studied for spherical NPs; however, the role of local surface curvature of nonspherical NPs in the surface phase separation of end-grafted polymer ligands remains an open question. Here, we examined phase separation in mixed monolayers of incompatible polystyrene and poly(ethylene glycol) brushes end-capping the surface of gold nanorods in a good solvent.

Applying Heteroatom Substitution in Organic Photovoltaics.

Poly(3-alkylthiophene) (P3AT) has been a central focus of research on organic photovoltaics (OPVs) for well over a decade. Due to their controlled synthesis P3ATs have proven to be a vital model system for developing an understanding of the effects of polymer structure on optoelectronic properties and blend morphology in bulk heterojunction OPVs. Similar to their thiophene counterparts, selenophene and tellurophene can be polymerized in a controlled manner.

Poly(3-alkylthiophene)- block-poly(3-alkylselenophene)s: Conjugated Diblock Co-polymers with Atypical Self-Assembly Behavior.

Understanding self-assembly behavior and resulting morphologies in block co-polymer films is an essential aspect of chemistry and materials science. Although the self-assembly of amorphous coil-coil block co-polymers is relatively well understood, that of semicrystalline block co-polymers where each block has distinct crystallization properties remains unclear. Here, we report a detailed study to elucidate the rich self-assembly behavior of conjugated thiophene-selenophene (P3AT- b-P3AS) block co-polymers.

Self-Organization and Charge Transport Properties of Selenium and Tellurium Analogues of Polythiophene.

A series of conjugated polymers comprising polythiophene, polyselenophene, and polytellurophene with branched 3,7-dimethyloctyl side chains, well-matched molecular weight, dispersity, and regioregularity is synthesized. The ionization potential is found to vary from 5.14 to 5.

Synthesis of fused-ring aza-dipyrromethenes from aromatic nitriles.

Aza-dipyrromethenes are ligands for a number of useful fluorescent dyes and electronic materials. They have high absorption in the red and NIR range. Fused-ring aza-dipyrromethenes cannot be synthesized through the same methods used to make aza-dipyrromethenes, which are common commercial dyes.

Patchy Nanofibers from the Thin Film Self-Assembly of a Conjugated Diblock Copolymer.

An unexpected morphology comprising patchy nanofibers can be accessed from the self-assembly of an all-conjugated, polyselenophene-block-polythiophene copolymer. This morphology consists of very small (<10 nm), polythiophene- and polyselenophene-rich domains and is unprecedented for both conjugated polymers and diblock copolymers in general. We propose that the patchy morphology occurs from the enhanced miscibility of the blocks arising from the longer alkyl chains in comparison to similar block copolymers with shorter alkyl chains, which fully phase separate, as well as the difference in rigidity between the polythiophene and polyselenophene blocks.

Synthesis of Macrocyclic Poly(3-hexylthiophene) and Poly(3-heptylselenophene) by Alkyne Homocoupling.

Here we report the synthesis of cyclic samples of poly(3-hexylthiophene) (P3HT, degrees of polymerization = 25, 40, and 75) and poly(3-heptylselenophene) (P37S, DP = 30). Cyclization was accomplished using a mild alkyne-alkyne homocoupling procedure. Alkyne-terminated poly(ethylene glycol) was then coupled to residual uncyclized polymers, which were subsequently removed by column chromatography, enabling isolation and characterization of pure cyclic polymers.

Increasing Polymer Solar Cell Fill Factor by Trap-Filling with F4-TCNQ at Parts Per Thousand Concentration.

Intrinsic traps in organic semiconductors can be eliminated by trap-filling with F4-TCNQ. Photovoltaic tests show that devices with F4-TCNQ at parts per thousand concentration outperform control devices due to an improved fill factor. Further studies confirm the trap-filling pathway and demonstrate the general nature of this finding.

Spatial distribution of proteins in the quagga mussel adhesive apparatus.

The invasive freshwater mollusc Dreissena bugensis (quagga mussel) sticks to underwater surfaces via a proteinacious 'anchor' (byssus), consisting of a series of threads linked to adhesive plaques. This adhesion results in the biofouling of crucial underwater industry infrastructure, yet little is known about the proteins responsible for the adhesion. Here the identification of byssal proteins extracted from freshly secreted byssal material is described.