Indium tin oxide (ITO) is a transparent conducting material that is widely used in devices where high transparency of the electrodes is required, such as flat panel and liquid crystal displays, touch panels, smart windows, and many others. ITO layers are deposited on a large scale by magnetron sputtering and then structured by lithography to define desired patterns of transparent electrodes. Here, a method for direct printing of transparent conductive patterns from ITO nanoparticle ink is communicated. The method combines inkjet printing with fast flash lamp annealing whereby the main novelty is to use an additional layer of a colored organic dye onto printed ITO to increase light absorption. The dye coating is instantly heated together with the underlying ITO layer by a light pulse, leading to an instant rise of the surface temperature, which is translated into improved optoelectronic properties of the ITO layers. Inkjet‐printed ITO patterns processed with the dye‐assisted flash lamp annealing exhibit a transmittance of up to 88% at 550 nm and resistivity of 3.1 × 10−3Ω cm. Transparent touch‐sensing trackpad and capacitive touch sensors are demonstrated based on the printed ITO patterns, which can be utilized in transparent security systems and other transparent Internet‐of‐Things devices.
The integration of energy harvesting and energy storage in a single device both enables the conversion of ambient energy into electricity and provides a sustainable power source for various electronic devices and systems. On the other hand, mechanical flexibility, coupled with optical transparency of the energy storage devices, is required for many applications, ranging from self-powered rolled-up displays to wearable optoelectronic devices. We integrate a piezoelectric poly(vinylidene-trifluoroethylene) (P(VDF-TrFE)) film into a flexible supercapacitor system to harvest and store the energy. The asymmetric output characteristics of the piezoelectric P(VDF-TrFE) film under mechanical impacts results in effective charging of the supercapacitors. The integrated piezo-supercapacitor exhibits a specific capacitance of 50 F g −1 . The open-circuit voltage of the flexible and transparent supercapacitor reached 500 mV within 20 s during the mechanical action. Our hybridized energy harvesting and storage device can be further extended to provide a sustainable power source for various types of sensors integrated into wearable units.
12 October 2020 in Journal of Materials Chemistry A