Fluorination is a common strategy for improving the electronic properties of π-conjugated materials, and this has shown to be important for applications in organic electronics, especially for the fabrication of...

We provide the initial demonstration of a general thin film deposition technique that leverages the unique solubility properties of supercritical fluids. The technique is the solution-phase analogue of physical vapor deposition and allows thin films of a semiconducting polymer to be grown without the need for in situ chemical reactions. Film growth is approximately linear with time, indicating that film thickness can be controlled in a straightforward manner by varying the time of deposition. To further demonstrate the flexibility of the technique, we demonstrate precise control over the location of material deposition using a combination of photolithography and resistive heating. The potential for scalable manufacturing is demonstrated by use of a master to control deposition onto a flexible polymer film. Finally, we demonstrate a unique deposition capability of this technique by depositing patterns onto the curved interior of a hemisphere made from a silicone elastomer. This capability is not possible with any printing or line-of-sight deposition technique. More generally, the ability to control the deposition of solution processed materials with high accuracy provides the long sought after bridge between top-down and bottom-up self-assembly.

Polyethylene is amongst the most used polymers, finding a plethora of applications in our lives owing to its high impact resistance, non-corrosive nature, light weight, cost effectiveness, and easy processing into various shapes from different sizes. Despite these outstanding features, the commodity polymer has been underexplored in the field of organic electronics. This work focuses on the development of new polymer blends based on a low molecular weight linear polyethylene (LPE) derivative with a high-performance diketopyrrolopyrrole-based semiconducting polymer. Physical blending of the polyethylene with semiconducting polymers was performed at ratios varying from 0 to 75 wt.%, and the resulting blends were carefully characterized to reveal their electronic and solid-state properties. The new polymer blends were also characterized to reveal the influence of polyethylene on the mechanical robustness and stretchability of the semiconducting polymer. Overall, the introduction of LPE was shown to have little to no effect on the solid-state properties of the materials, despite some influence on solid-state morphology through phase separation. Organic field-effect transistors prepared from the new blends showed good device characteristics, even at higher ratios of polyethylene, with an average mobility of 0.151 cm2 V−1 s−1 at a 25 wt.% blend ratio. The addition of polyethylene was shown to have a plasticizing effect on the semiconducting polymers, helping to reduce crack width upon strain and contributing to devices accommodating more strain without suffering from decreased performance. The new blends presented in this work provide a novel platform from which to access more mechanically robust organic electronics and show promising features for the utilization of polyethylene for the solution processing of advanced semiconducting materials toward novel soft electronics and sensors.

We investigated the self-assembly of polymers in supercritical fluids by depositing thin films of isotactic polypropylene from n-pentane:acetone solutions and studying their structure. The deposition technique leverages a maximum in...

Detection and characterization of biomolecular interactions, such as protein–protein interactions (PPIs), are critical to a fundamental understanding of biochemical processes, thus being a driver of innovation for drug discovery, clinical diagnostics, and protein engineering. Among the many sensor types used to probe PPIs, organic field-effect transistors are particularly desirable due to their unique features, including tunability, sensitivity, low-power requirements, and multi-parameter readouts. This work describes the development of a biosensor based on organic field-effect transistors, covalently functionalized at the surface with an engineered ubiquitin variant for the specific and sensitive detection of ubiquitin-specific protease 8 (USP8). The resulting sensor was carefully characterized to reveal both electronic and solid-state properties. The sensing platform showed high sensitivity (sub-nanomolar analyte concentrations) and selectivity for USP8 and robust performance that suggests that it may be highly tunable. The sensing system introduced in this work provides a detection method for PPIs, which constitutes a promising platform for advanced biotechnology applications.

Flexible pressure sensors with self-healing abilities for wearable electronics are being developed, but generally either lack autonomous self-healing properties or require sophisticated material processing methods. To address this challenge, we...

The self-assembly of isotactic polypropylene films from supercritical n-pentane was studied. The effects of solution thermodynamics and fluid mechanics were reported.

In order to develop more atom-economical deposition methods for polymer semiconductors, we investigated physical supercritical fluid deposition (p-SFD) to form thin films of a popular bithiophene semiconducting polymer (PBTTT). Depositions...