Printing Fabrication of Bulk Heterojunction Solar Cells and In Situ Morphology Characterization.

Polymer-based materials hold promise as low-cost, flexible efficient photovoltaic devices. Most laboratory efforts to achieve high performance devices have used devices prepared by spin coating, a process that is not amenable to large-scale fabrication. This mismatch in device fabrication makes it difficult to translate quantitative results obtained in the laboratory to the commercial level, making optimization difficult.

Fast printing and in situ morphology observation of organic photovoltaics using slot-die coating.

The mini-slot-die coater offers a simple, convenient, materials-efficient route to print bulk-heterojunction (BHJ) organic photovoltaics (OPVs) that show efficiencies similar to spin-coating. Grazing-incidence X-ray diffraction (GIXD) and GI small-angle X-ray scattering (GISAXS) methods are used in real time to characterize the active-layer formation during printing. A polymer-aggregation-phase-separation-crystallization mechanism for the evolution of the morphology describes the observations.

Sequential deposition: optimization of solvent swelling for high-performance polymer solar cells.

Organic solar cells based on a typical DPP polymer were systematically optimized by a solvent swelling assisted sequential deposition process. We investigated the influence of solvent swelling on the morphology and structure order of the swollen film and the resultant device performance. Morphological and structural characterization confirmed the realization of ideal bulk heterojunctions using a suitable swelling solvent.

New insights into morphology of high performance BHJ photovoltaics revealed by high resolution AFM.

Direct imaging of the bulk heterojunction (BHJ) thin film morphology in polymer-based solar cells is essential to understand device function and optimize efficiency. The morphology of the BHJ active layer consists of bicontinuous domains of the donor and acceptor materials, having characteristic length scales of several tens of nanometers, that reduces charge recombination, enhances charge separation, and enables electron and hole transport to their respective electrodes. Direct imaging of the morphology from the molecular to macroscopic level, though, is lacking.

Organic single-crystalline p-n junction nanoribbons.

This article focuses on the growth and transport properties of organic single-crystalline p-n junction nanoribbons. The development of organic nanoelectronics requires the fabrication of organic nanometer-sized p-n junctions for high-performance devices and integrated circuits. Here we demonstrate the formation of single-crystalline p-n junction nanoribbons of organic semiconductors by selective crystallization of copper hexadecafluorophthalocyanine (F(16)CuPc, n-type) on copper phthalocyanine (CuPc, p-type) single-crystalline nanoribbons.

Facile synthesis of bimetallic Ag/Ni core/sheath nanowires and their magnetic and electrical properties.

This paper describes a facile method for coating Ag nanowires with uniform, ferromagnetic sheaths made of polycrystalline Ni. A typical sample of these core/sheath nanowires had a saturation magnetization around 33 emu g(-1). We also demonstrated the use of this magnetic property to align the nanowires by simply placing a suspension of the nanowires on a substrate in a magnetic field and allowing the solvent to evaporate.