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.

Chitosan-Based Electronics: The Importance of Acid Strength and Plasticizing Additives on Device Performance.

A rise in demand for disposable consumer electronics such as smart packaging, wearable electronics, and single-use point-of-source sensors requires the development of eco-friendly and compostable electronic materials. Chitosan is derived from crustacean waste and offers high dielectric constant values without requiring rigorous purification, making it sustainable for large-scale electronic device manufacturing. When processed in acidic media, the protonated backbone of chitosan pairs with counterions from the acid dissociation to form chitosan thin films with electrical double layers (EDLs) and tunable capacitive properties.

Linking Electronic and Structural Disorder Parameters to Carrier Transport in a Modern Conjugated Polymer.

Understanding charge transport in conjugated polymers is crucial for the development of next-generation organic electronic applications. It is presumed that structural disorder in conjugated polymers originating from their semicrystallinity, processing, or polymorphism leads to a complex energetic landscape that influences charge carrier transport properties. However, the link between polymer order parameters and energetic landscape is not well established experimentally.

CO Responsive Thin-Film Transistors Using Conjugated Polymer Complexes with Single-Walled Carbon Nanotubes.

Introduction of amidine groups within the side chains of a conjugated polyfluorene was carried out using copper-catalyzed azide-alkyne cycloaddition. The resulting polymer was shown to form strong supramolecular interactions with the sidewalls of single-walled carbon nanotubes (SWNTs), forming polymer-nanotube complexes that exhibited solubility in various organic solvents. It was shown that the polymer-SWNT complexes were responsive to CO, where the amidine groups formed amidinium bicarbonate salts upon CO exposure, causing the polymer-SWNT complexes to precipitate.

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.

Ion transport in polymerized ionic liquids: a comparison of polycation and polyanion systems.

The correlation among chemical structure, mesoscale structure, and ion transport in 1,2,3-triazole-based polymerized ionic liquids (polyILs) featuring comparable polycation and polyanion backbones is investigated by wide-angle X-ray scattering (WAXS), differential scanning calorimetry, and broadband dielectric spectroscopy (BDS). Above the glass transition temperature, , higher ionic conductivity is observed in polycation polyILs compared to their polyanion counterparts, and ion conduction is enhanced by increasing the counterion volume in both polycation or polyanion polyILs. Below , polyanions show lower activation energy associated with ion conduction.

Water-Soluble Reversible Photo-Cross-Linking Polymer Dielectrics.

Effective recycling of mixed materials requires the separation of the different components without the need for toxic solvents. One approach involves utilizing a water-soluble coating with reversible photo-cross-linkers, making it robust until end of life where it can then be dissolved in water after de-cross-linking. Here, a novel coumarin methacrylate monomer and its nitroxide-mediated copolymerization to create poly((methacrylic acid)-co-(styrene sulfonate)-co-(coumarin methacrylate)) for water-soluble thin films are reported.

Axial Phenoxylation of Aluminum Phthalocyanines for Improved Cannabinoid Sensitivity in OTFT Sensors.

Cannabis producers, consumers, and regulators need fast, accurate, point-of-use sensors to detect Δ-tetrahydrocannabinol (THC) and cannabidiol (CBD) from both liquid and vapor source samples, and phthalocyanine-based organic thin-film transistors (OTFTs) provide a cost-effective solution. Chloro aluminum phthalocyanine (Cl-AlPc) has emerged as a promising material due to its unique coordinating interactions with cannabinoids, allowing for superior sensitivity. This work explores the molecular engineering of AlPc to tune and enhance these interactions, where a series of novel phenxoylated R-AlPcs are synthesized and integrated into OTFTs, which are then exposed to THC and CBD solution and vapor samples.

Blade Coating Poly(3-hexylthiophene): The Importance of Molecular Weight on Thin-Film Microstructures.

Poly(3-hexylthiophene) is one of the most prevalent and promising conjugated polymers for use in organic electronics. However, the deposition of this material in thin films is highly dependent on the process, such as blade coating versus spin coating and material properties such as molecular weight. Typically, large polymer dispersity makes it difficult to isolate the effect of molecular weight without considering a distribution.

Mechanically Robust Poly(ionic liquid) Block Copolymers as Self-Assembling Gating Materials for Single-Walled Carbon-Nanotube-Based Thin-Film Transistors.

The proliferation of high-performance thin-film electronics depends on the development of highly conductive solid-state polymeric materials. We report on the synthesis and properties investigation of well-defined cationic and anionic poly(ionic liquid) AB-C type block copolymers, where the AB block was formed by random copolymerization of highly conductive anionic or cationic monomers with poly(ethylene glycol) methyl ether methacrylate, while the C block was obtained by post-polymerization of 2-phenylethyl methacrylate. The resulting ionic block copolymers were found to self-assemble into a lamellar morphology, exhibiting high ionic conductivity (up to 3.

Not Just Surface Energy: The Role of Bis(pentafluorophenoxy) Silicon Phthalocyanine Axial Functionalization and Molecular Orientation on Organic Thin-Film Transistor Performance.

Understanding the effect of surface chemistry on the dielectric-semiconductor interface, thin-film morphology, and molecular alignment enables the optimization of organic thin-film transistors (OTFTs). We explored the properties of thin films of bis(pentafluorophenoxy) silicon phthalocyanine () evaporated onto silicon dioxide (SiO) surfaces modified by self-assembled monolayers (SAMs) of varying surface energies and by weak epitaxy growth (WEG). The total surface energy (γ), dispersive component of the total surface energy (γ), and polar component of the total surface energy (γ) were calculated using the Owens-Wendt method and related to electron field-effect mobility of devices (μ), and it was determined that minimizing γ and matching γ yielded films with the largest relative domain sizes and highest resulting μ.

Surface engineering of zinc phthalocyanine organic thin-film transistors results in part-per-billion sensitivity towards cannabinoid vapor.

Phthalocyanine-based organic thin-film transistors (OTFTs) have been demonstrated as sensors for a range of analytes, including cannabinoids, in both liquid and gas phases. Detection of the primary cannabinoids, Δ-tetrahydrocannabinol (THC) and cannabidiol (CBD), is necessary for quality control and regulation, however, current techniques are often not readily available for consumers, industry, and law-enforcement. The OTFT characteristics, X-ray diffraction (XRD) spectra, and grazing incident wide angle x-ray scattering (GIWAXS) spectra of two copper and three zinc phthalocyanines, with varying degrees of peripheral fluorination, were screened to determine sensitivity to THC vapor.

Low-Cost Silicon Phthalocyanine as a Non-Fullerene Acceptor for Flexible Large Area Organic Photovoltaics.

We demonstrate large-area (1 cm) organic photovoltaic (OPVs) devices based on bis(tri-n-butylsilyl oxide) silicon phthalocyanine (3BS)-SiPc as a non-fullerene acceptor (NFA) with low synthetic complexity paired with poly(3-hexylthiophene) (P3HT) as a donor polymer. Environment-friendly nonhalogenated solvents were used to process large area OPVs on flexible indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrates. An alternate sequentially (Alt-Sq) blade-coated active layer with bulk heterojunction-like morphology is obtained when using (3BS)-SiPc processing with o-xylene/1,3,5-trimethylbenzene solvents.

Interfacial Ultraviolet Cross-Linking of Green Bilayer Dielectrics.

Electronic waste is a growing challenge which needs to be addressed through the integration of high-performance sustainable materials. Green dielectric polymers such as poly(vinyl alcohol) (PVA) have favorable electrical properties but are challenging to integrate into thin film electronics due to their physical properties. For example, PVA suffers from poor film formation and is hygroscopic.

Strong Magnetic Field Annealing for Improved Phthalocyanine Organic Thin-Film Transistors.

Thin-film microstructure, morphology, and polymorphism can be controlled and optimized to improve the performance of carbon-based electronics. Thermal or solvent vapor annealing are common post-deposition processing techniques; however, it can be difficult to control or destructive to the active layer or substrates. Here, the use of a static, strong magnetic field (SMF) as a non-destructive process for the improvement of phthalocyanine (Pc) thin-film microstructure, increasing organic thin-film transistor (OTFTs) mobility by twofold, is demonstrated.

Direct Arylation: A Greener Synthesis of Anthraquinone-Naphthalene diimide-Based Small Chromophores for Applications in Organic Thin Film Transistors.

In this paper, we report the design and synthesis of three naphthalene diimide- (NDI) and anthraquinone- (AQ) based organic chromophores derived from direct arylation reactions; NDI-AQ, AQ-NDI-AQ and NDI-AQ-NDI. Compared to classic cross-coupling reactions, this method reduced the number of synthetic and purification steps. The chemical structures, photophysical and electrochemical properties of these molecules were characterized using UV-vis spectroscopy, fluorescence emission spectroscopy and cyclic voltammetry (CV).

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.

Metal phthalocyanines: thin-film formation, microstructure, and physical properties.

Metal phthalocyanines (MPcs) are an abundant class of small molecules comprising of a highly conjugated cyclic structure with a central chelated metal ion. Due to their remarkable chemical, mechanical, and thermal stability MPcs have become popular for a multitude of applications since their discovery in 1907. The potential for peripheral and axial functionalization affords structural tailoring to create bespoke MPc complexes for various next generation applications.

Design of ternary additive for organic photovoltaics: a cautionary tale.

Silicon phthalocyanines as ternary additives are a promising way to increase the performance of organic photovoltaics. The miscibility of the additive and the donor polymer plays a significant role in the enhancement of the device performance, therefore, ternary additives can be designed to better interact with the conjugated polymer. We synthesized -9'-heptadecanyl-2,7-carbazole functionalized SiPc ((CBzPho)-SiPc), a ternary additive with increased miscibility in poly[-90-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT).

Layer-by-Layer Organic Photovoltaic Solar Cells Using a Solution-Processed Silicon Phthalocyanine Non-Fullerene Acceptor.

Silicon phthalocyanines (SiPcs) are promising, inexpensive, and easy to synthesize non-fullerene acceptor (NFA) candidates for all-solution sequentially processed layer-by-layer (LbL) organic photovoltaic (OPV) devices. Here, we report the use of bis(tri--butylsilyl oxide) SiPc ((3BS)-SiPc) paired with poly(3-hexylthiophene) (P3HT) and poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))--(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) donors in an LbL OPV structure. Using a direct architecture, P3HT/(3BS)-SiPc LbL devices show power conversion efficiencies (PCEs) up to 3.

The Need to Pair Molecular Monitoring Devices with Molecular Imaging to Personalize Health.

By enabling the non-invasive monitoring and quantification of biomolecular processes, molecular imaging has dramatically improved our understanding of disease. In recent years, non-invasive access to the molecular drivers of health versus disease has emboldened the goal of precision health, which draws on concepts borrowed from process monitoring in engineering, wherein hundreds of sensors can be employed to develop a model which can be used to preventatively detect and diagnose problems. In translating this monitoring regime from inanimate machines to human beings, precision health posits that continual and on-the-spot monitoring are the next frontiers in molecular medicine.

Use of Piers-Rubinsztajn Chemistry to Access Unique and Challenging Silicon Phthalocyanines.

Axial functionalization is one mode that enables the solubility of silicon phthalocyanines (SiPcs). Our group observed that the use of typical axial functionalization methodologies on reaction of ClSiPc with the chlorotriphenyl silane reagent unexpectedly resulted in the equal formation of triphenyl silyloxy silicon tetrabenzotriazacorrole ((3PS)-SiTbc) and the desired bis(tri-phenyl siloxy)-silicon phthalocyanine ((3PS)-SiPc). The formation of a (3PS)-SiTbc was unexpected, and the separation of (3PS)-SiTbc and (3PS)-SiPc was difficult.

Ionic Liquid Containing Block Copolymer Dielectrics: Designing for High-Frequency Capacitance, Low-Voltage Operation, and Fast Switching Speeds.

Polymerized ionic liquids (PILs) are a potential solution to the large-scale production of low-power consuming organic thin-film transistors (OTFTs). When used as the device gating medium in OTFTs, PILs experience a double-layer capacitance that enables thickness independent, low-voltage operation. PIL microstructure, polymer composition, and choice of anion have all been reported to have an effect on device performance, but a better structure property relationship is still required.

Variance-resistant PTB7 and axially-substituted silicon phthalocyanines as active materials for high-Voc organic photovoltaics.

While the efficiency of organic photovoltaics (OPVs) has improved drastically in the past decade, such devices rely on exorbitantly expensive materials that are unfeasible for commercial applications. Moreover, examples of high voltage single-junction devices, which are necessary for several applications, particularly low-power electronics and rechargeable batteries, are lacking in literature. Alternatively, silicon phthalocyanines (R-SiPc) are inexpensive, industrially scalable organic semiconductors, having a minimal synthetic complexity (SC) index, and are capable of producing high voltages when used as acceptors in OPVs.