A direct/facile strategy for synchronizing the gas receptor and signal transport layers is demonstrated for highly sensitive flexible NOx sensors.

Solution‐processed polar hydroxyl containing polymers such as poly(4‐vinylphenol) are widely utilized in organic filed‐effect transistors (OFETs) due to their high dielectric constant (k) and excellent insulating properties owing to the crosslinking through their hydroxyl groups. However, hydroxyl functionalities can function as trapsites, and their crosslinking reactions decrease the k value of materials. Hence, in this study, new solution‐processable copolymers containing both carboxyl and hydrophobic functionalities are synthesized. A fluorophenyl azide (FPA) based UV‐assisted crosslinker is also employed to promote the movement of polar carboxyl groups toward the bulk region and the hydrophobic functionalities to the surface region, thereby maintaining the high‐k characteristics and hydrophobic surface in thin film. Thus, the addition of an FPA crosslinker eliminates the trapsites on the surface, allowing a stable operation and efficient charge transport. Additionally, the solution‐processability enables the production of uniform and thin films to yield OFETs with stable and low‐voltage driving characteristics. The printed layers are also applied as gate dielectrics for floating gate memory devices and in integrated one‐transistor‐one‐transistor based memory cells, displaying their excellent memory performance. The synthesis and fabrication strategies employed in this study can become useful guidelines for the production of high‐k dielectrics for stable OFETs and other applications.

This work reports the molecular engineering of polymeric semiconductors to get highly soluble inks, which enables the uniform deposition of semiconductors and contributes to high-performance transistor and sensor devices.

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Commercial hydrogen (H 2 ) sensors operate at high temperatures, which increases power consumption and poses a safety risk owing to the flammable nature of H 2 . Here, a polymer−noble metal−metal oxide film is fabricated using the spin-coating and printing methods to realize a highly sensitive, low-voltage operation, wide-operating-concentration, and near-monoselective H 2 sensor at room temperature. The H 2 sensors with an optimized thickness of Pd nanoparticles and SnO 2 showed an extremely high response of 16,623 with a response time of 6 s and a recovery time of 5 s at room temperature and 2% H 2 . At the same time, printed flexible sensors demonstrate excellent sensitivity, with a response of 2300 at 2% H 2 . The excellent sensing performance at room temperature is due to the optimal SnO 2 thickness, corresponding to the Debye length and the oxygen and H 2 spillover caused by the optimized coverage of the Pd catalyst. Furthermore, multistructures of WO 3 and SnO 2 films are used to fabricate a new type of dual-signal sensor, which demonstrated simultaneous conductance and transmittance, i.e., color change. This work provides an effective strategy to develop robust, flexible, transparent, and long-lasting H 2 sensors through large-area printing processes based on polymer−metal−metal oxide nanostructures.

Although semiconducting single-walled carbon nanotubes (sc-SWNTs) exhibit excellent sensing properties for various gases, commercialization is hampered by several obstacles. Among these, the difficulty in reproducibly fabricating sc-SWNT films with uniform density and thickness is the main one. Here, a facile fabrication method for sc-SWNT-based hydrogen (H 2 ) sensors with excellent reproducibility, high sensitivity, and selectivity against CO, CO 2 , and CH 4 is reported. Uniform-density and monolayer sc-SWNT films are fabricated using chemical immobilized through the click reaction between azide-functionalized polymer-wrapped sc-SWNTs and immobilized alkyne polymer on a substrate before decorating with Pd nanoparticles (0.5-3.0 nm). The optimized sc-SWNT sensor has a high room-temperature response of 285 with the response and recovery times of 10 and 3 s, respectively, under 1% H 2 gas in air. In particular, this sensor demonstrates highly selective H 2 detection at room temperature (25 °C), compared to other gases and humidity. Therefore, the chemical immobilization of the monolayer SWNT films with reproducible and uniform density has the potential for large-scale fabrication of robust room-temperature H 2 sensors.

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In this study, we investigated facile “dragging mode” electrohydrodynamic (EHD) jet printing of a polymer-wrapped semiconducting single-walled carbon nanotube (s-SWCNT) ink, for fabrication of NO gas-sensing field-effect transistors (FETs). The...