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Facile, room-temperature, and surfactant-free seed-mediated chemical bath deposition was developed to directly grow CuBi2O4 nanostructures on an electrode substrate for applications in electrochemical reforming of glucose and photoelectrochemical (PEC) hydrogen generation. The metal precursor concentration and Cu2+/Bi3+ molar ratio were found to be decisive factors in determining the structure of CuBi2O4, and single crystal CuBi2O4 submicron-square columns (microCuBi2O4), nano-square columns (nanoCuBi2O4), and c-axis oriented nano-square columns (c-nanoCuBi2O4) were selected for detailed electrochemical and PEC characterization. The results of Tauc plots and ultraviolet photoelectron spectroscopy (UPS) resolved the band structure of these CuBi2O4 compounds. Mott–Schottky and UPS analyses showed that these CuBi2O4 compounds had flat-band potentials of >1.10 V vs. RHE, which makes them promising photocathodes for PEC hydrogen generation. The synthesized CuBi2O4 compounds exhibited different levels of electrocatalytic activity towards electroreforming of glucose, in the order of nanoCuBi2O4 > c-nanoCuBi2O4 > microCuBi2O4, which is attributed to the structure-dependent kinetics of the chemical reaction between glucose and electrochemically activated Cu species in CuBi2O4 at elevated anodic potentials. Additionally, all synthesized CuBi2O4 samples showed high selectivity (faradaic efficiency > 93%) for formate generation from electro-oxidative conversion of glucose. This study opens up a new avenue for the synthesis of nanostructured CuBi2O4 with promising bi-functionality towards PEC biomass reforming.

In this study, CoOx nanoparticles decorated CuBi2O4 submicron-sized square columns (microCuBi2O4|CoOx) modified electrodes were fabricated and their electrocatalytic properties were investigated. microCuBi2O4, for the first time, was directly grown onto the electrode substrate using chemical bath deposition (CBD) at room temperature, whereas microCuBi2O4|CoOx was prepared by subjecting microCuBi2O4 to additional CBD process and subsequent electrochemical treatment. It was found that the crystalinity of microCuBi2O4 and the amount of CoOx play a decisive role in the overall electrocatalytic activity of microCuBi2O4|CoOx. In addition, the redox couples of the active species, responsible for the electrocatalytic glucose oxidation, in microCuBi2O4 and CoOx overlaps, and these active species exert a synergetic electrocatalytic effect in enhancing the overall electrocatalytic activity, in terms of overpotential and catalytic current, of microCuBi2O4|CoOx towards glucose oxidation. Under optimal conditions, the developed microCuBi2O4|CoOx exhibits a promising sensing characteristics for glucose detection, including a high sensitivity of 383.0 ± 32.3 µA/cm2/mM, a low limit of detection of 0.8 µM, a wide linear range upto 8.0 mM, a fast response time (t95) of

We report a fabrication method of controlling the doped concentration of phosphorescent dye to induce the trap-site in an emitting layer (EML) for an efficient near-infrared (NIR) organic upconversion device (OUD). Such an OUD was used as a device configuration of ITO/mixed layer of chloroaluminum phthalocyanine and C60/1,1-bis(di-4-tolylaminophenyl) cyclohexane/4,4′ -Bis(N-carbazolyl)-1,1′ -biphenyl doped with fac-tris (2-phenylpyridine) iridium (III) [Ir(ppy)3]/4,7-diphenyl-l,10-phenanthroline/CS2CO3/Ag to provide a green emission under NIR illumination. Our optimized OUD with a high Ir(ppy)3 doped concentration of ∼13 wt% exhibited a higher electroluminescent efficiency in the display unit and was suitable for inducing a large amount of trap-sites in the EML, which effectively blocked the hole and electron carrier in the EML. To induce the trap-site in the EML by the doping process, we used a hole- and electron-only device to examine the OUD with a lower dark current density. As a result, an optimal OUD with a current gain as high as 21,300 (defined as the light current density divided by dark current density) at a driving voltage of 3 V was successfully achieved.

We report here synthesis and photovoltaic properties of three merocyanines dyes (DPPT, DTPT, 1-NPPT) which are functionalized with electron withdrawing thiazolidenemalononitrile and electron rich diarylamine functionalities. It is found that structural feature of the diarylamino groups has a profound effect on the physical properties such as the absorption spectrum, oxidation potential, and HOMO/LUMO energy levels. The compound DTPT containing a better electron-donating ditolyl group, exhibits red-shifted absorption with relatively higher molar extinction coefficient, indicating its better light-harvesting ability. Hole mobility of these compounds is found to be strongly dependent on the various intermolecular interactions. Interestingly, single crystal structures reveal that the crystal packing motifs are rather closely related to the observed hole mobility in a trend of DPPT > DTPT > 1-NPPT. Vacuum-processed small-molecule organic solar cells were fabricated using the title merocyanines as p-type materials (donor) in combination with fullerene (C60 or C70) as n-type material (acceptor) with various device configurations. Among them, the DPPT-based devices outperform the devices based on DTPT and 1-NPPT. The power conversion efficiency (PCE) of DPPT-based device was improved from 1.55% of a BHJ device to 2.63% of a PMHJ device and 3.52% of a PMHJ device without the thin donor layer.

Organic materials are used in novel optoelectronic devices because of the ease and high compatibility of their fabrication processes. Here, we demonstrate a low-driving-voltage cathodic-controlled organic upconverter with a mapping application that converts near-infrared images to produce images of visible blood vessels. The proposed upconverter has a multilayer structure consisting of a photosensitive charge-generation layer (CGL) and a phosphorescent organic light-emitting diode (OLED) for producing clear images with a high resolution of 600 dots per inch. In this study, temperature-dependent electrical characterization was performed to analyze the interfacial modification of the cathodic-controlled upconverter. The result shows that the upconverter demonstrated a high conversion efficiency of 3.46% because of reduction in the injection barrier height at the interface between the CGL and the OLED.

The organic donor/acceptor of chloroaluminum phthalocyanine and C 70 as a charge generation layer (CGL) enabled a realization of near-infrared (NIR) image sensing for a highly efficient organic up-conversion device. The well-alignment energy level of CGL played an important role in controlling the conduction-path of a hole carrier for our device (i.e., electron-rich type), which effectively blocked the injection carrier at the interface of the anode/CGL. The proposed up-converter used was a device configuration of ITO/CGL/1,1-bis(di-4-tolylaminophenyl) cyclohexane/4,4′-Bis(N-carbazolyl)-1,1′-biphenyl doped with fac-tris (2-phenylpyridine) iridium (III)/2-phenyl-9-(3-(2-phenyl-1,10-phenanthrolin-9-yl)phenyl)-1,10-phenanthroline/CS 2 CO 3 /Ag to provide a green emission under NIR illumination. As a result, an optimal device with a current gain as high as 10 000 (i.e., on-off ratio from dark to light testing) at a driving voltage of 3 V was successfully achieved. In addition, our transparent device (i.e., device with ultra-thin cathode of ∼ 12 nm Ag) was proposed from a clear three-dimensional image of a real object with a high resolution of 420 dots per inch, indicating the high sensitivity of this organic device for NIR sensing.

Transparent organic upconversion devices are shown in a night-vision demonstration of a real object under near-infrared (NIR) illumination in the dark. An extraordinarily high current gain - reflecting the on-off switching effect - greater than 15 000 at a driving voltage of 3 V is demonstrated, indicating the high sensitivity to NIR light and potential of using the proposed upconverter in practical applications. A maximum luminance exceeding 1500 cd m(-2) at 7 V is achieved. Unlike previous studies, where 2D aperture projection is reported, the current study shows 3D images of real objects under NIR illumination in the dark.