Polaron states in organic thin-film transistors (TFTs) were investigated by the electron spin resonance (ESR) technique. Gate-field-dependent and temperature-dependent single-Lorentzian ESR spectra were observed for field-induced polarons in pentacene TFTs, demonstrating the effect of motional narrowing due to polaron diffusion. Analyses of the ESR linewidth revealed a considerably long trapping time (tau_(C) approximately 0.7 ns), the variation of which is discussed in terms of the multiple trap-and-release model.

A fibre actuator that generates a large strain with high specific power represents a promising strategy to develop novel wearable devices and robotics. We propose a new coiled-fibre actuator based on highly drawn, hard linear low-density polyethylene (LLDPE) fibres. Driven by resistance heating, the actuator can be operated at temperatures as low as 60 °C and uses only 20% of the power consumed by previously coiled fibre actuators when generating 20 MPa of stress at 10% strain. In this temperature range, 1600 W kg−1 of specific work (8 times that of a skeletal muscle) at 69 MPa of tensile stress (230 times that of a skeletal muscle) with a work efficiency of 2% is achieved. The actuator generates strain as high as 23% at 90 °C. Given the low driving temperature, the actuator can be combined with common fabrics or stretchable conductive elastomers without thermal degradation, allowing for easy use in wearable systems. Nanostructural analysis implies that the lamellar crystals in drawn LLDPE fibres are weakly bridged with each other, which allows for easy deformation into compact helical shapes via twisting and the generation of large strain with high work efficiency.

Highly‐conductive organic charge‐transfer complex films are successfully fabricated by an inkjet printing technique in which the soluble donor and acceptor components are printed individually and combine on the substrate to form complex films. The method enables us to produce conductive (10 S/cm) tetrathiafulvalene‐tetracyanoquinodimethane thin film electrodes that afford high performance organic transistors and inverters operating at low voltages.

Lead halide perovskite is a candidate for nextgeneration solar cells. Improvements in photovoltaic conversion efficiency and cell durability in different environments, such as moisture, heat, and light, are pertinent for practical use. Researchers must solve the problem of light-induced degradation (LID) of perovskite solar cells. Oxygen accelerates LID. However, a buffer layer between the electron transport layer (ETL)/ perovskite interface suppresses LID. Herein, we report the influence of oxygen and the buffer layer on LID at the perovskite [(FA 0.83 MA 0.17 ) 0.95 Cs 0.05 (I 0.95 Br 0.05 ) 3 with 2.5 mol % RbI additive]/ hole transport layer (HTL) and ETL/perovskite interfaces by hard X-ray photoelectron spectroscopy. We confirmed that oxygen accelerated the increase in the fraction of neutral iodine at the perovskite/HTL interface after light illumination and the introduction of a self-assembled monolayer as the buffer layer greatly suppressed the increase in the fraction of neutral lead at the ETL/perovskite interface, suggesting that photoelectrochemical reactions at the interfaces play an important role in the LID of perovskite solar cells.

The interface engineering of dibenzotetrathiafulvalene organic thin-film transistors (OTFTs) is reported. Polycrystalline-film morphologies are successfully controlled by surface treatments of silicon dioxide dielectric substrates using hexamethyldisilazane, a silane coupling agent, to tune the average lateral grain sizes between 0.2 and 20μm. The field-effect mobility of the resulting OTFTs is approximately 0.55cm2∕Vs. The effects of the grain sizes on subthreshold properties are discussed in terms of the charge transport against the grain boundaries through the films.

In this work the authors fabricated patterned thin films made of highly conductive organic charge-transfer complexes using the ink-jet printing technique. The overprinted films of BO9(C14-TCNQ)4 exhibit low sheet resistivity and are available for carrier injection and interconnection of organic field-effect transistors (FETs). The performance of pentacene thin film FETs, where the top contact and bottom contact are ink-jet-printed organic electrodes, demonstrates the potential of organic/organic heterointerfaces.

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Kelvin probe force microscopy has been employed to monitor the cross-sectional potential profile in lead-halide perovskite photovoltaic cells. From systematic investigations on many devices under varying bias voltage and light illumination conditions, we are able to deduce quantitative profile features with low noise that allows us to compare the local electronic properties in the working devices against numerical calculations. We applied the technique to devices before and after degradation. Through the profile change before and after, we located the degraded components and inferred the source of the loss of the performance.