A polyamide 6,6 (PA66) fabric pre-treated with a double barrier dielectric (DBD) atmospheric plasma in air was coated with 1 and 5 layers of an intrinsically conducting glycerol-doped PEDOT:PSS polymer (PEDOT:PSS + GLY) with the final objective of developing a cost-competitive and temperature controllable flexible-heating element to be used in clothing encapsulated between an outer and an inner separator layer in order to provide heat-reflecting properties and uniform temperature distribution, respectively. FTIR, DSC, TGA, SEM, EDS, XRD and DMA analyses show significant changes in morphology, chemistry, enthalpy, crystallinity and glass transition temperature confirming that PEDOT:PSS and glycerol are not only spread over the PA66 yarn surfaces but are dispersed in the bulk facilitating relaxation and increasing structure and chain flexibility. Electrochemical and electrical resistivity (ρ) measurements confirm that the plasma treated PA66 coated with 5 layers of PEDOT:PSS + GLY presents the highest stability, resistance and capacitive behaviour, and the best capability of storing electrical energy. This configuration needs only 7.5 V to induce a temperature change up to 38 °C at a current density of 0.3 A g−1. The desired temperature is easily adjustable as a function of the applied voltage and by the number of coated layers of PEDOT:PSS + GLY. Despite the need to improve the uniformity of the coating thickness on the fabric for uniform heat generation, the observed results are quite impressive since they can be compared to the temperature obtained in carbon nanotube composites using similar voltages. This cost-competitive, safe, highly flexible and stable thermoelectric fabric has potential for use in large area textiles as a heating element in a wide range of applications such as garments, carpets, blankets and automotive seats.
27 September 2019 in ACS Applied Materials & Interfaces
Self‐powered photodetectors (PDs) have been recognized as one of the developing trends of next‐generation optoelectronic devices. Herein, it is shown that by introducing a thin layer of SnO film between the Si substrate and the ZnO film, the self‐powered photodetector Al/Si/SnO/ZnO/ITO exhibits a stable and uniform violet sensing ability with high photoresponsivity and fast response. The SnO layer introduces a built‐in electrostatic field to highly enhance the photocurrent by over 1000%. By analyzing energy diagrams of the p‐n junction, the underlying physical mechanism of the self‐powered violet PDs is carefully illustrated. A high photo‐responsivity (R) of 93 mA W−1 accompanied by a detectivity (D*) of 3.1 × 1010 Jones are observed under self‐driven conditions, when the device is exposed to 405 nm excitation laser wavelength, with a laser power density of 36 mW cm−2 and at a chopper frequency of 400 Hz. The Si/SnO/ZnO/ITO device shows an enhancement of 3067% in responsivity when compared to the Al/Si/ZnO/ITO. The photodetector holds an ultra‐fast response of ≈ 2 µs, which is among the best self‐powered photodetectors reported in the literature based on ZnO.
Here, the ability of using p-type tin oxide (SnO x ) thin films as a thermal sensor has been investigated. Firstly, the thermoelectric performance was optimized by controlling the thickness of the SnO x film from 60 up to 160 nm. A high Seebeck coefficient of +263 μ V K −1 and electrical conductivity of 4.1 × 10 2 (S m −1 ) were achieved in a 60 nm thick SnO x film, due to a compact nanostructured film and the absence of the Sn metallic phase, which was observed for the thicker SnO x film leading to a typical thermoelectric transport properties of a n-type Sn film. Moreover, x-ray photoelectron spectroscopy revealed the co-existence of SnO (79.7%) and SnO 2 (20.3%) phases in the 60 nm thick SnO x film, while the optical measurements revealed an indirect gap of 1.8 eV and a direct gap of 2.7 eV, respectively. The 60 nm-SnO x thin film have been tested as a thermoelectric touch sensor, achieving a
V
signal /
V
noise ≈ 20, with a rise time <1 s. Therefore, this work provides an efficient way for developing highly efficient thermal sensors with potential use in display technologies.