The recent rapid development of transparent electronics, notably displays and control circuits, requires the development of highly transparent energy storage devices, such as supercapacitors. The devices reported to date utilize carbon-based electrodes for high performance, however at the cost of their low transparency around 50%, insufficient for real transparent devices. To overcome this obstacle, in this communication highly transparent supercapacitors were fabricated based on ZnO/MnO₂ nanostructured electrodes. ZnO served as an intrinsically transparent skeleton for increasing the electrode surface, while MnO₂ nanoparticles were applied for high capacitance. Two MnO₂ synthesis routes were followed, based on the reaction of KMnO₄ with Mn(Ac)₂ and PAH, leading to the synthesis of β-MnO₂ with minority α-MnO₂ nanoparticles and amorphous MnO₂ with embedded β-MnO₂, respectively. The devices based on such electrodes showed high capacitances of 2.6 mF cm⁻² and 1.6 mF cm⁻², respectively, at a scan rate of 1 mV s⁻¹ and capacitances of 104 μF cm⁻² and 204 μF cm⁻² at a very high rate of 1 V s⁻¹, not studied for transparent supercapacitors previously. Additionally, the Mn(Ac)₂ devices exhibited very high transparencies of 86% vs. air, far superior to other transparent energy storage devices reported with similar charge storage properties. This high device performance was achieved with a non-acidic LiCl gel electrolyte, reducing corrosion and handling risks associated with conventional highly concentrated acidic electrolytes, enabling applications in safe, wearable, transparent devices.

Amorphous In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) are employed in current flat-panel displays. It is known that deposition conditions and post-deposition thermal annealing affect structure and electrical properties of a-IGZO thin films. It was previously reported that total pressure during sputter-deposition deteriorates subthreshold swing, defect density and operation characteristics of a-IGZO TFTs. Here, we provide comprehensive results on effects of total pressure on film density, chemical composition, and TFT characteristics. Rutherford backscattering measurements detected a small amount of argon incorporated in all of the a-IGZO films. We found that increasing the total pressure deteriorated TFT characteristics; i.e., saturation mobility was dropped from 10 to 4 cm ² /(V·s), subthreshold swing was increased from 0.2 to 0.5 V/dec, and threshold voltage was positive-shifted from 2 to 15 V. It is related to increased oxygen concentration and decreased weight density of the a-IGZO films. Thermal desorption spectra showed that amounts of weakly-bonded oxygen increased as the total pressure increased, which is considered to be related to the TFT deterioration.

With the development of novel device applications, e.g. in the field of robust and recyclable paper electronics, came an increased demand for the understanding and control of IGZO Schottky contact properties. In this work, a fabrication and characterization of flexible Ru–Si–O/IGZO Schottky barriers on paper is presented. It is found that an oxygen-rich atomic composition and microstructure of Ru–Si–O containing randomly oriented Ru inclusions with diameter of 3–5 nm embedded in an amorphous SiO ₂ matrix are effective in preventing interfacial reactions in the contact region, allowing to avoid pre-treatment of the semiconductor surface and fabricate reliable diodes at room temperature characterized by Schottky barrier height and ideality factor equal 0.79 eV and 2.13, respectively.

With the development of novel device applications, e.g., in the field of Internet of Things or point-of-care personalized diagnostic systems, came an increased demand for MESFETs for fast and low-power consumption integrated circuits and active-matrix displays. In this paper, we present fabrication and characterization of transparent Ru-Si-O/In-Ga-Zn-O MESFETs on flexible substrates. The use of transparent conducting oxide, namely, Ru-Si-O, as Schottky gate electrode, allows for processing the devices at room temperature, enabling the utilization of such low-temperature substrates as polyethylene terephthalate foil and paper. It was shown that tuning the device geometry allows realization of transistors providing on-current up to 2 mA, while the highest on-to-off current ratio equals 2 × 10 ⁵ , with off-current below 1 nA, carrier mobility in the channel exceeds 9 cm ² ·V ^-1 ·s ^-1 , and subthreshold swing is below 250 mV·decade ^-1 .