The preparation of water‐processable nanoparticles (NPs) of polymer semiconductors assembled using an amphiphilic rod‐coil block copolymer (BCP), and their application to active layer sustainable fabrication of organic photovoltaic devices are reported. The hydrophobic rod is a p‐type semiconductor, while the hydrophilic coil is a short chain of poly‐4‐vinylpyridine strongly interacting with [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM). Through miniemulsion technique stable water‐suspended blend NPs are obtained, avoiding nonconducting surfactant use. The amphiphilic BCP fulfills a dual function, as surfactant for stabilizing the blend NPs and as electron donor material in the active layer. After mild annealing of obtained films, blend NPs interconnect with each other forming compact and uniform layers with adequate morphology for efficient charge percolation to the electrodes. Space‐charge limited hole mobility of ≈5 × 10−3 cm2 V−1 s−1 in BCP‐only NP films annealed at 120 °C (corresponding to a tenfold increase in mobility as compared to the p‐type semiconductor films spin‐coated from chlorinated solvents) indicates strong p–p interactions in the self‐assembled NPs. Blend NPs were covered with thin PC61BM layer and used as active layers in photovoltaic devices displaying high photocurrents (11.5 mA cm−2) and average power conversion efficiency of 2.53% after annealing at 90 °C.

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Noble metal anisotropic nanostructures have achieved a growing interest in both academic and industrial domains mostly because of their shape-dependent plasmonic properties in the near-infrared region. In this paper, gold and gold-silver anisotropic nanostructures were synthesized in very high shape-yields through a wet, seed-mediated approach based on the use of nearly spherical silver nanoparticles as seeds and chitosan as stabilizing agent. Two chitosans of different origin and molecular properties were selected for the synthetic pathway, leading to the formation of variously sized and shaped end products. In detail, quite homogeneous nanoplatelets of about 25-nm size and 7-nm thickness or nearly spherical, highly porous nanocages of about 50-nm size were obtained, depending on the type of polysaccharide employed. The shape transition towards anisotropic morphologies occurred through a slow, spontaneous process, in which the chitosan nature seemed to play a key role. As expected, both nanoplatelets and nanocages exhibit shape-dependent plasmonic features and surface properties tunable for a variety of application fields. To prove this point, the nanostructures were successfully post-functionalized with poly(10,12-pentacosadiynoic acid) (PCDA), a carboxylic-endowed diacetylene able to anchor on noble metal substrates, to obtain versatile, chromic platforms suitable for sensing and spectroscopic purposes.