Fabrication of organic photovoltaic devices by the layer-by-layer polyelectrolyte deposition method

Organic photovoltaic cells were fabricated by the layer-by-layer polyelectrolyte deposition process by which the film thickness can be controlled accurately. Ruthenium/rhenium complexes containing poly(p-phenylenevinylene) and sulfonated polyaniline were used in the process. This new method provides flexibility in the fabrication of multilayer polymeric devices with well-defined structure. © 2005 IEEE.published_or_final_versio

Fabrication of Photovoltaic Cell from Ruthenium Containing Polymer Using Layer by Layer Polyelectrolytes Adsorption Technique

Multilayer photovoltaic devices were fabricated by the sequence adsorption of different polyelectrolytes. A ruthenium terpyridine complex containing poly(p-phenylenevinylene) was used as the polycation layer. This polymer has been shown to exhibit large photo-sensitivity due to the presence of the ruthenium complex, which has relatively long-lived excited state. This polymer absorbs strongly in the visible region at ca. 480-550 nm and it can act as the electron transporter. Sulfonated polyaniline was used as the hole-transporting polyanion layer. The ITO/(polyanion/polycation) n/A1 devices were found to exhibit photovoltaic properties under the illumination of AM1 solar radiation. The short-circuit current I sc, open-circuit voltage V oc, and the fill factor FF were measured to be 14 μA/cm 2, 0.84 V and 0.16 respectively. It was found that the power conversion efficiencies of the devices were dependent on the device thickness. This simple layer-by-layer self-assembly method allowed us to control the devices thickness accurately.published_or_final_versio

Low-band-gap, sublimable rhenium(I) diimine complex for efficient bulk heterojunction photovoltaic devices

The fabrication of efficient bulk heterojunction photovoltaic cells using the chlorotricarbonyl rhenium(I) diimine complex as photosensitizer was discussed. The complex has a lower band gap, which can be adjusted easily by changing the structure of the ligand. The electric properties of the complex were studied using time-of-flight analysis. It was observed that the rhenium complex showed bipolar charge transport character with relatively high electron and hole mobilities.published_or_final_versio

Nanosized micelles formed by the self-assembly of amphiphilic block copolymers with luminescent rhenium complexes

We have synthesized a series of polystyrene-block-poly(4-vinylpyridine)s (PS-&-PVP) to which luminescent tricarbonyl(2,2′-bipyridyl)rhenium(I) complexes were attached. The rhenium complexes could induce the self-assembly of the copolymers into nanosized micelles with different shapes and dimensions, depending on the block size distribution of the copolymers and the solvent system being used. In general, spherical micelles were observed when methanol, a nonsolvent for the polystyrene block, was added to a copolymer solution in dichloromethane. Micellization was observed when the added methanol concentration was approximately 30%. When toluene, a nonsolvent for the poly(4-vinylpyridine) block, was added to the copolymer solution in dichloromethane, micelles with different interesting shapes were observed. For copolymers with larger PVP block size, spherical micelles were observed. When the relative block size of the PVP block was reduced, the micelles gradually changed to disk or vesicle structures and then to rodlike structures. The rhenium complex can act as a luminescent probe in the resulting nanosized micelles and provide sufficient contrast for electron microscopic studies. Significant changes in luminescence spectra were observed after the micellization.link_to_subscribed_fulltex

Efficient Photodetectors Fabricated from a Metal-Containing Conjugated Polymer by a Multilayer Deposition Process

Photovoltaic devices were fabricated by layer-by-layer polyelectrolyte deposition techniques using bisterpyridyl ruthenium(II) complex containing conjugated polymer as the polycation and sulfonated polyaniline as the polyanion. The maximum external quantum efficiencies of the devices were in the range of 1-2%, and the power conversion efficiency was on the order of 10 -3% with the fill factor of 0.2.link_to_subscribed_fulltex

Fabrication of photovoltaic cells using rhenium diimine complex containing polyelectrolytes by the layer-by-layer electrostatic self-assembly method

A series of poly(p-phenylenevinylene)s polycations incorporated with rhenium(I) chlorotricarbonyl bis(phenylimino)acenaphthene complex and pendant pyridinium side groups was synthesized. Due to the presence of ionic pendant groups, the polymers could be used to form multilayer thin films with sulfonated polyaniline (SPAN) by the layer-by-layer (LbL) electrostatic assembly process. The rhenium complexes could function as photosensitizers and SPAN could serve as a charge carrying polymer, and the resulting multilayer films form the active layer of photovoltaic cells. Upon irradiation of the photovoltaic devices by simulated AM 1.5 solar light, the power conversion efficiencies were measured to be of the order of 10 -4%. Measurement of the incident photon-to-electron conversion efficiency (IPCE) at different wavelengths confirmed that the photosensitization was due to the presence of rhenium complexes in the polymer. The photocurrent generation and decay processes could be simulated by triexponential functions, which consisted of a rapid process followed by a relatively slow process. © 2007 Springer Science+Business Media, LLC.link_to_subscribed_fulltex

Synthesis and characterization of random and block copolymers with pendant rhenium diimine complexes by controlled radical polymerization

We report the polymerization of rhenium-containing methacrylates by atom transfer radical polymerization. The structure of the monomer was confirmed by X-ray crystallography, which showed the bulkiness of the metal-complex moiety. The rhenium complexes were polymerized in the presence of copper(I) bromide, 1,1,4,7,7-pentamethyl-diethylenetriamine, and methyl 2-bromopropionate. They were copolymerized with methyl methacrylate in different monomer ratios. An ABA triblock copolymer was also synthesized with poly(methyl methacrylate) as the macroinitiator. When 2,2'-bipyridine was used as the ligand for the copper catalyst in the polymerizations, it underwent a ligand exchange process with the iminopyridine ligand in the monomer. The neutral rhenium complex in the homopolymers and copolymers could be converted into ionic forms by the replacement of the chloride with an imidazole ligand, and the solubility of the resulting ionic polymers was greatly enhanced. The photosensitizing properties of the doped and undoped polymer films were investigated by the measurement of the photocurrent response under an externally applied electric field. The photoconductivities of the polymers were approximately 10 -12-10 13 Ω 1 cm -1. The experimental quantum efficiencies were simulated with On-sager's theory, and they showed that the initial quantum yield and thermalization distance were 10 -3 and 1.7 nm, respectively. Transmission electron microscopy showed that the rhenium complexes aggregated to form domains with dimensions of approximately 20-30 nm. © 2005 Wiley Periodicals, Inc.link_to_subscribed_fulltex