With atomic-layer-deposition grown zinc oxide as the electron selective layer, we developed plastic substrate compatible processing for organic photovoltaic devices and demonstrated flexible inverted organic solar cells on poly(ethylene naphthalate) with a power conversion efficiency of 4.18%.

Conformal deposition of Pt nanoparticles with good dispersion on carbon nanotubes (CNTs) is performed by atomic layer deposition (see image). The particle density and loading depend on surface condition and cycle number. The anode made of CNTs exhibits a higher catalytic efficiency than a commercial E‐TEK electrode, suggesting that it is a promising technique for application in proton‐exchange membrane fuel cells.

Our controlled growth of Ni/ZnO nanorod heterostructures by MOVPE opens up significant opportunities for the fabrication of spintronic device structures on a single nanorod. The simple yet accurate thickness control allows tunable magnetic properties in nanosized magnetic layers on individual nanorods due to a crossover from superparamagnetism to ferromagnetism. These magnetic building blocks may be used as components for nanoscale spin-valve transistors, spin lightemitting diodes, and nonvolatile storage and logic devices. More generally, we believe that the simple ªbottom±upº heterostructural approach might readily be expanded to create many other magnetic-semiconductor nanorod heterostructures. ExperimentalFor the fabrication of magnetic-metal/ZnO nanorod heterostructures, ZnO nanorods were prepared on Al 2 O 3 (0001) substrates using a low-pressure MOVPE system [11]. No metal impurity catalyst was deposited on the substrates. For ZnO nanorod growth, diethylzinc, and oxygen were employed as reactants with argon as the carrier gas. For magnetic metal evaporation on the ZnO nanorods, Ni was evaporated on vertically aligned ZnO nanorods at room temperature using an electron-gun evaporation system with a base pressure 7±8 10 ±8 torr [12]. During metal evaporation, metal flux was incident on the top surfaces of the ZnO nanorods. The deposition rate was monitored using a thickness monitor and controlled to be 0.2 s ±1 . Metal layer thickness was in the range of 50±400 , as determined by TEM [12].The crystal orientation of nanorod heterostructures was characterized using SR-XRD. The SR-XRD measurements of Ni/ZnO nanorod heterostructures were performed using a four-circle diffractometer of the 3C2 synchrotron X-ray diffraction beam line at the Pohang Accelerator Laboratory [17]. The beam size at the focal point was typically less than 1 mm 2 and a fixed-exit double-crystal monochromator was used. The diffracted beam intensity was measured using a scintillation detector. High X-ray flux yielded a significant signal-to-noise ratio to measure very thin Ni layers on the nanorods. The crystal orientation of Ni layers was confirmed using TEM. Details in the SEM and TEM measurements have been reported elsewhere [11,12].The topography and magnetic images of Ni/ZnO nanorods were measured using a MFM that was modified from a commercial AFM. The MFM was operated in amplitude detection mode. MFM tips are AFM cantilevers coated with 30 nm of cobalt and have a resonance frequency of 18 kHz. Before measuring the magnetic properties of samples, they were saturated in a fixed direction along their easy axis under the applied magnetic field of 3000 Oe, after which an MFM image was taken to determine its magnetization. The AFM and MFM images were measured simultaneously on the same region.Further magnetic properties of Ni/ZnO nanorod heterostructures were measured using both SQUID and a high-sensitivity AGM at room temperature in a field of up to 60 kOe. For the data presented here, the diamagnetic background from Al 2 O 3 (0001) substr...

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