Solution-Assembled Blends of Regioregularity-Controlled Polythiophenes for Coexistence of Mechanical Resilience and Electronic Performance

Achieving metal-like malleability and ductility in Ag2Te1-x S x inorganic thermoelectric semiconductors with high mobility

Inorganic semiconductor Ag2Te1-x S x has been recently found to exhibit unexpected plastic deformation with compressive strain up to 30%. However, the origin of the abnormal plasticity and how to simultaneously achieve superb ductility and high mobility are still elusive. Here, we demonstrate that crystalline/amorphous Ag2Te1-x S x (x = 0.3, 0.4, and 0.5) composites can exhibit excellent compressive strain up to 70% if the monoclinic Ag2Te phase, which commonly exists in the matrix, is eliminated. Significantly, an ultra-high tensile elongation reaching 107.3% was found in Ag2Te0.7S0.3, which is the highest one yet reported in the system and even surpasses those achieved in some metals and high-entropy alloys. Moreover, high mobility of above 1000 cm2 V-1 s-1 at room temperature and good thermoelectric performance are simultaneously maintained. A modified Ashby plot with ductility factor versus carrier mobility is thereby proposed to highlight the potential of solid materials for applications in flexible/wearable electronics.

High-Molecular-Weight Electroactive Polymer Additives for Simultaneous Enhancement of Photovoltaic Efficiency and Mechanical Robustness in High-Performance Polymer Solar Cells

The development of small-molecule acceptors (SMAs) has significantly enhanced the power conversion efficiency (PCE) of polymer solar cells (PSCs); however, the inferior mechanical properties of SMA-based PSCs often limit their long-term stability and application in wearable power generators. Herein, we demonstrate a simple and effective strategy for enhancing the mechanical robustness and PCE of PSCs by incorporating a high-molecular-weight (MW) polymer acceptor (P _A, P(NDI2OD-T2)). The addition of 10-20 wt % P _A leads to a more than 4-fold increase in the mechanical ductility of the SMA-based PSCs in terms of the crack onset strain (COS). At the same time, the incorporation of P _A into the active layer improves the charge transport and recombination properties, increasing the PCE of the PSC from 14.6 to 15.4%. The added P _As act as tie molecules, providing mechanical and electrical bridges between adjacent domains of SMAs. Thus, for the first time, we produce highly efficient and mechanically robust PSCs with a 15% PCE and 10% COS at the same time, thereby demonstrating their great potential as stretchable or wearable power generators. To understand the origin of the dual enhancements realized by P _A, we investigate the influence of the P _A content on electrical, structural, and morphological properties of the PSCs.

Manipulating nanoscale structure to control functionality in printed organic photovoltaic, transistor and bioelectronic devices

Printed electronics is simultaneously one of the most intensely studied emerging research areas in science and technology and one of the fastest growing commercial markets in the world today. For the past decade the potential for organic electronic (OE) materials to revolutionize this printed electronics space has been widely promoted. Such conviction in the potential of these carbon-based semiconducting materials arises from their ability to be dissolved in solution, and thus the exciting possibility of simply printing a range of multifunctional devices onto flexible substrates at high speeds for very low cost using standard roll-to-roll printing techniques. However, the transition from promising laboratory innovations to large scale prototypes requires precise control of nanoscale material and device structure across large areas during printing fabrication. Maintaining this nanoscale material control during printing presents a significant new challenge that demands the coupling of OE materials and devices with clever nanoscience fabrication approaches that are adapted to the limited thermodynamic levers available. In this review we present an update on the strategies and capabilities that are required in order to manipulate the nanoscale structure of large area printed organic photovoltaic (OPV), transistor and bioelectronics devices in order to control their device functionality. This discussion covers a range of efforts to manipulate the electroactive ink materials and their nanostructured assembly into devices, and also device processing strategies to tune the nanoscale material properties and assembly routes through printing fabrication. The review finishes by highlighting progress in printed OE devices that provide a feedback loop between laboratory nanoscience innovations and their feasibility in adapting to large scale printing fabrication. The ability to control material properties on the nanoscale whilst simultaneously printing functional devices on the square metre scale is prompting innovative developments in the targeted nanoscience required for OPV, transistor and biofunctional devices.

Conjugated polymer/paraffin blends for organic field-effect transistors with high environmental stability

Improving the environmental stability of conjugated polymers remains a fundamental challenge that limits their widespread adoption and commercial application in electronic and photonic devices. Although paraffin can have excellent barrier properties against moisture in ambient air, the use of conjugated polymer/paraffin blends to fabricate organic field-effect transistors (OFETs) with high environmental stability has not been attempted. Here, we demonstrate that conjugated polymer/paraffin blends can greatly enhance the environmental stability of OFETs. Compared to conventional systems such as poly(3-hexylthiophene) (P3HT)/polystyrene and P3HT/polydimethylsiloxane blends, P3HT/paraffin blends exhibit superior environmental stability after 30 days of exposure to the ambient atmosphere. Furthermore, the conjugated polymer/paraffin blends provide stable electronic properties under severe mechanical deformation [a strain (ε) of ∼150%], overcoming a critical challenge arising from the use of fragile crystalline conjugated polymer films for flexible and stretchable electronic devices. In comparison with a conventional spin-coating method, a shear-coating technique provides enhanced molecular ordering and alignment, resulting in improved charge carrier mobility in the blend film OFETs. In particular, shearing in the evaporation regime improves the molecular ordering and alignment of the blend films more than shearing in the Landau-Levich regime. Interestingly, the environmental stability of the sheared blend films varies depending on the shear speed. Specifically, OFETs based on blend films sheared at 0.5 and 6.0-10.0 mm s^-1 exhibit excellent environmental stability, maintaining 80% of their initial mobility after 30 days of exposure to air. In contrast, the environmental stability of the OFETs decreases considerably when the blend films are sheared at 1.0-4.0 mm s^-1; the mobility decreases to as low as ∼20% of the initial value.

Synthesis and crystallization behavior of regioregular-block-regiorandom poly(3-hexylthiophene) copolymers

Regioregular–regiorandom poly(3-hexylthiophene) copolymers, synthesized by chain-transfer polycondensation, show strong crystallinity due to their one-sided distribution of regiodefects.

Effect of a conjugated/elastic block sequence on the morphology and electronic properties of polythiophene based stretchable block copolymers

We report the synthesis, morphology, and electronic properties of intrinsically stretchable AB-type, ABA-type, and BAB-type block copolymers (BCPs) of poly(3-hexylthiophene) (P3HT: A block) and elastic poly(octylene oxide) (POO: B block).

An electrolyte-gated polythiophene transistor for the detection of biogenic amines in water

An ultra-low voltage operatable thin-film transistor based on a polythiophene pendant with a carboxy sidechain can detect biogenic amines in water.