The effects of annealing and fullerene loading in regioregular poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM) based bulk heterojunction photovoltaics have been investigated. Under specific loading and annealing conditions, a combination of morphological and electronic factors can be brought to play to achieve optimal filling factors, open-circuit voltage (Voc), and short-circuit current density (Jsc). We demonstrate that this occurs at surprisingly low loadings of PCBM and annealing temperatures nearing the melting point of the polymer. Further, we report power conversion efficiencies approaching 5% in the P3HT:PCBM system.

Multipod gold nanocrystals have been synthesized via a simple solution-phase chemical reduction method at room temperature. Two types of structurally different particles are observed, including the regular tripod, which lies on the substrate with its {111} plane, and the cross-like tetrapod that sits on its {100} plane. Both structures have pods of 10 nm sizes and grow along 110 directions. Variously shaped particles, including tadpole-like or teardrop-like monopods, 90 degrees L-shaped, 180 degrees I-shaped, and 120 degrees V-shaped bipods, T-shaped, Y-shaped, and regular triangular tripods, and cross-like tetrapods, have been produced. Due to the high conductivity of metal, these branched structures are quite promising considering their applications as interconnections in the "bottom-up" self-assembly approach toward future nanocircuits and nanodevices, as well as in other related fields.