High-Performance Photovoltaic Hydrogen Sensing Platform with a Light-Intensity Calibration Module.

Although battery-free gas sensors (, photovoltaic or triboelectric sensors) have recently appeared to resolve the power consumption issue of conventional chemiresistors, severe technical barriers still remain. Especially, their signals varying under ambient conditions such as light intensity restrict the utilization of these sensors. Insufficient sensing performances (low response and slow sensing rate) of previous battery-free sensors are also an obstacle for practical use.

Plasmon enhanced up-conversion nanoparticles in perovskite solar cells for effective utilization of near infrared light.

As an alternative to silicon-based solar cells, organic-inorganic hybrid perovskite solar cells (PSCs) have attracted much attention and achieved a comparable power conversion efficiency (PCE) to silicon-based ones, although the perovskite materials can absorb only visible light. Hence, the challenge remains to enhance the PCE utilizing near infrared (NIR) light in the solar light spectrum. One of the easiest ways to utilize the NIR is to incorporate NIR active materials in PSCs such as up-conversion nanoparticles (UCNPs); however, such a stratergy is not simple to adopt in PSCs due to the inherent vurnerability of perovskite materials towards moisture.

Improvement of perovskite crystallinity by omnidirectional heat transfer radiative thermal annealing.

As promising photo-absorbing materials for photovoltaics, organic-inorganic hybrid perovskite materials such as methylammonium lead iodide and formamidinium lead iodide, have attracted lots of attention from many researchers. Among the various factors to be considered for high power conversion efficiency (PCE) in perovskite solar cells (PSCs), increasing the grain size of perovskite is most important. However, it is difficult to obtain a highly crystalline perovskite film with large grain size by using the conventional hot-plate annealing method because heat is transferred unidirectionally from the bottom to the top.

Surface conversion of ZnO nanorods to ZIF-8 to suppress surface defects for a visible-blind UV photodetector.

ZnO nanomaterials are promising building blocks for an efficient UV photodetector; however, their slow sensing behavior and undesired response to visible light, which are attributed to surface defects, such as oxygen or zinc vacancies, are challenges that remain to be addressed. Here, we transformed the ZnO nanorod surface into a zeolitic imidazolate framework-8 (ZIF-8) to eliminate ZnO surface defects. Vertical-type photodetectors were fabricated incorporating a Schottky junction at the ZIF-8/gold (Au) top electrode and could respond to UV light with a rapid response and recovery (1-2 s) and demonstrated a UV-to-visible rejection ratio in the order of 10, qualifying them as efficient visible-blind UV photodetectors.

Effect of Channel Thickness, Annealing Temperature and Channel Length on Nanoscale Ga2O3-In2O3-ZnO Thin Film Transistor Performance.

We demonstrated the effect of active layer (channel) thickness and annealing temperature on the electrical performances of Ga2O3-In2O3-ZnO (GIZO) thin film transistor (TFT) having nanoscale channel width (W/L: 500 nm/100 μm). We found that the electron carrier concentration of the channel was decreased significantly with increasing the annealing temperature (100 degrees C to 300 degrees C). Accordingly, the threshold voltage (V(T)) was shifted towards positive voltage (-12.

Palladium Nanoribbon Array for Fast Hydrogen Gas Sensing with Ultrahigh Sensitivity.

A lithographically aligned palladium nano-ribbon (Pd-NRB) array with gaps of less than 40 nm is fabricated on a poly(ethylene terephthalate) substrate using the direct metal transfer method. The 200 μm Pd-NRB hydrogen gas sensor exhibits an unprecedented sensitivity of 10(9) % after bending treatment, along with fast sensing behavior (80% response time of 3.6 s and 80% recovery time of 8.

A tunable sub-100 nm silicon nanopore array with an AAO membrane mask: reducing unwanted surface etching by introducing a PMMA interlayer.

Highly ordered silicon (Si) nanopores with a tunable sub-100 nm diameter were fabricated by a CF4 plasma etching process using an anodic aluminum oxide (AAO) membrane as an etching mask. To enhance the conformal contact of the AAO membrane mask to the underlying Si substrate, poly(methyl methacrylate) (PMMA) was spin-coated on top of the Si substrate prior to the transfer of the AAO membrane. The AAO membrane mask was fabricated by two-step anodization and subsequent removal of the aluminum support and the barrier layer, which was then transferred to the PMMA-coated Si substrate.

Orientation-Controllable ZnO Nanorod Array Using Imprinting Method for Maximum Light Utilization in Dye-Sensitized Solar Cells.

We present a holey titanium dioxide (TiO2) film combined with a periodically aligned ZnO nanorod layer (ZNL) for maximum light utilization in dye-sensitized solar cells (DSCs). Both the holey TiO2 film and the ZNL were simultaneously fabricated by imprint technique with a mold having vertically aligned ZnO nanorod (NR) array, which was transferred to the TiO2 film after imprinting. The orientation of the transferred ZNL such as laid, tilted, and standing ZnO NRs was dependent on the pitch and height of the ZnO NRs of the mold.

Palladium-decorated hydrogen-gas sensors using periodically aligned graphene nanoribbons.

Polymer residue-free graphene nanoribbons (GNRs) of 200 nm width at 1 μm pitch were periodically generated in an area of 1 cm(2) via laser interference lithography using a chromium interlayer prior to photoresist coating. High-quality GNRs were evidenced by atomic force microscopy, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy measurements. Palladium nanoparticles were then deposited on the GNRs as catalysts for sensing hydrogen gases, and the GNR array was utilized as an electrically conductive path with less electrical noise.