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Influence of annealing temperature and thickness on the optical characteristics of the blend of poly (3-hexylthiophene) (P3HT) and Phenyl C61 butyric acid methylester (PCBM) layer has been investigated in this report. Photoactive polymer material (P3HT:PCBM) was deposited on indium tin oxide (ITO) substrate by spin-coating. The morphology of P3HT:PCBM composite layer was investigated by Atomic Force Microscope (AFM). The surface roughness was found to reduce after heat treatment. The absorption of the composite layer was found to increase with its number of layer (thickness). On the other hand, the photoluminescence (PL) quenching, which indicates efficient charge separation in the bulk heterojunction, was found higher for the thinner layer. Absorption was also found to increase with the annealing temperature. Therefore, to optimize the thickness of the P3HT:PCBM photoactive layer that will provide best absorption while providing efficient charge separation, annealing at optimized temperature might be an effective tool.

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We successfully confirmed spin injection and detection in the MnAs/GaAs/InAs hybrid system on GaAs(111)B through lateral nonlocal spin valve (NLSV) measurement at 1.5 K and 77 K. Surprisingly, we found larger NLSV signals at 77 K than that at 1.5 K. This seems to be interesting behavior compared to typical temperature dependent spin injection and detection study. We studied in depth the NLSV signals to extract spin parameters such as spin diffusion length and spin injection efficiency in the hybrid system. We found spin diffusion length to be ∼10 μm and ∼7 μm at 1.5 K and 77 K, respectively, and also found spin injection efficiency to be ∼1.6% and ∼2.5% at 1.5 K and 77 K, respectively. The reason behind higher injection efficiency at 77 K comes from better impedance matching between MnAs and InAs at 77 K than that at 1.5 K due to large temperature variation of MnAs resistivity.

Facile electrochemical synthesis of ZnO@Co and ZnO@Ni hybrid core@shell nanowires with enhanced ferromagnetism.