ABSTRACT
Copper thiocyanate (CuSCN) is introduced as a hole-injection/hole-transport layer (HIL/HTL) for solution-processed organic light-emitting diodes (OLEDs). The OLED devices reported here with CuSCN as HIL/HTL perform significantly better than equivalent devices fabricated with a PEDOT:PSS HIL/HTL, and solution-processed, phosphorescent, small-molecule, green OLEDs with maximum luminance ≥10 000 cd m(-2) , maximum luminous efficiency ≤50 cd A(-1) , and maximum luminous power efficiency ≤55 lm W(-1) are demonstrated.
ABSTRACT
In this paper, we report a fabrication, characterization and stability study of p-GaN/n-ZnO nanorod heterojunction light-emitting devices (LEDs). The LEDs were assembled from arrays of n-ZnO vertical nanorods epitaxially grown on p-GaN. LEDs showed bright electroluminescence in blue (440 nm), although weaker violet (372 nm) and green-yellow (550 nm) spectral components were also observed. The device characteristics are generally stable and reproducible. The LEDs have a low turn-on voltage (â¼5 V). The electroluminescence (EL) is intense enough to be noticed by the naked eye, at an injection current as low as â¼ 40 µA (2.1 × 10(-2) A cm(-2) at 7 V bias). Analysis of the materials, electrical and EL investigations point to the role of a high quality of p-n nano-heterojunction which facilitates a large rectification ratio (320) and a stable reverse current of 2.8 µA (1.4 × 10(-3) A cm(-2) at 5 V). Stability of EL characteristics was investigated in detail. EL intensity showed systematic degradation over a short duration when the LED was bias-stressed at 30 V. At smaller bias (<20 V) LEDs tend to show a stable and repeatable EL characteristic. Thus a simple low temperature solution growth method was successfully exploited to realize nanorod/film heterojunction LED devices with predictable characteristics.
ABSTRACT
Recently, the ability to create bio-semiconductor hybrid devices has gained much interest for cell activity analysis. AlGaN material system has been demonstrated to be a promising cell-based biosensing platform due to a combination of unique properties, such as chemical inertness, optical transparency and low signal to noise ratios. To investigate the potential application of hybrid cell-AlGaN/GaN field effect transistor for cell electrophysiological monitoring, saos-2 human osteoblast-like cells were cultured in high density in non-metallized gate area of a transparent AlGaN/GaN heterostructure field effect transistor. We implemented and characterized the transistor recording of extracellular voltage in the cell-chip junction using the FET chip. The effect of ion channel blocker TEA on transistor signal was explored in order to test the capability of this hybrid chip for in vitro drug screening bioassay. Finally, the effect of cell adhesion on transistor signal was also studied by applying the protein kinase inhibitor H-7.
