Crystalline Au dendrites were formed by electrodeposition on a glassy carbon electrode from a solution of HAuCl(4) containing cysteine. The Au dendrites possessed a hierarchical architecture with three-fold symmetry; they comprised trunks, branches, and nanorod leaves, which all grew along the <111> direction.

This paper describes the optical responses and memory effects of poly͑3-hexylthiophene͒ ͑P3HT͒/ CdSe quantum dot ͑QD͒ thin-film transistors ͑TFTs͒. TFTs incorporating P3HT/CdSe QD blends as the active layer exhibited higher photocurrents than did the corresponding P3HT-only devices because the heterojunction between P3HT and the CdSe QDs enhanced the separation of excitons. Moreover, the CdSe QDs served as trap centers so that the memory effect was maintained for several hours, even when the device was operated without a gating voltage. Here, we demonstrate the potential applicability of such P3HT/CdSe QD TFTs through repeated optical programming and electrical erasing.

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The spin polarization of organic-ferromagnetic interfaces in an organic spin valve critically affects the efficiency of spin injection or detection. We examined the chemical and electronic properties of ferromagnetic Co deposited on organic Alq3 and the interfacial spin-polarized capability of the electronic states. Our x-ray photoemission spectra and calculations with density-functional theory indicate a sequential and unequal distribution of charge from Co clusters to N and then to O atoms in Alq3. The preferential orbital hybridization at specific functional sites produces efficient spin polarization of organic molecules. Element-specific measurements of x-ray magnetic circular dichroism demonstrate the preferential spin polarization in the lowest unoccupied molecular orbital state of N atoms at the complex interface for Co atop Alq3, which agrees satisfactorily with calculation. Our results indicate that an induced interfacial spin polarization on engineering the dominant reaction of Co with mainly N and O atoms in Alq3 might pave a way for effective spin filtering in organic spintronics.PACS number(s): 79.60. Fr, 75.70.Cn, 68.35.Fx, 75.76.+j Organic spin valves (OSV) in which an organic semicon ductor (OSC) spacer is sandwiched between two ferromagnetic (FM) electrodes have attracted much attention because of an enduring spin coherence of organic materials via weak spin-orbit coupling [1], Dediu et al. pioneered in achiev ing magnetoresistance (MR) up to 30% near 295 K in a LaovSrojMnOsfLSMOj/sexithiophenefTgj/LSMO OSV, ini tiating a great potential of organic-based spintronics [2], Xiong et al. subsequently made a remarkable observation of a giant MR at 40% at 11 K in a LSMO/Alq3/CoOSV [1], Among the most widely used OSC in OSV, tri(8-hydroxyquinoline) aluminum (Alq3) composed of 7r-conjugated molecules is considered to be a promising material for effective spin transport because of its great spin-relaxation time and unique molecular structure [1,3-6], The combination of Alq3 and d -band FM Co has achieved striking MR values [1,7-12], Although an ill-defined layer between Alq3 and top Co was manifested at an Alq3 thickness greater than 100 nm, it is one of few examples in which an OSV displayed a large MR [1], Such an ill-defined layer is ascribed to the diffusion of metal into a soft organic layer, which might be related to the disputed results of the MR sign and mechanism [1,12-15], To prevent the unexpected interdiffusion and chemical interaction at the interfacial region, a buffer layer inserted between the top Co and Alq3 has improved the device performance [9,16-18]. Although metal interdiffusion is preventable with those meth ods, it might not provide a deep understanding of the lacking essential mechanisms [19][20][21]. Moreover, in the case of an OSV with no buffer layer, a large MR was still achieved [1,8]. Various techniques have been used to engineer, to control, or to detect the efficient spin injection and transport [ 1,4,22,23] 'jenghan @ on traditionally applying a specific bias voltage to...

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