Effect of solvent and subsequent thermal annealing on the performance of phenylenevinylene copolymer: PCBM solar cells.

The morphology of the photoactive layer used in the bulk heterojunction photovoltaic devices is crucial for efficient charge generation and their collection at the electrodes. We investigated the solvent vapor annealing and thermal annealing effect of an alternating phenylenevinylene copolymer P:PCBM blend on its morphology and optical properties. The UV-visible absorption spectroscopy shows that both solvent and thermal annealing can result in self-assembling of copolymer P to form an ordered structure, leading to enhanced absorption in the red region and hole transport enhancement.

Effect of the incorporation of a low-band-gap small molecule in a conjugated vinylene copolymer: PCBM blend for organic photovoltaic devices.

The effect of the incorporation of a low-band-gap small-molecule BTD-TNP on the photovoltaic properties of vinylene copolymer P:PCBM bulk heterojunction solar cells has been investigated. The introduction of this small molecule increases both the short-circuit photocurrent and the overall power conversion efficiency of the photovoltaic device. The incident photon-to-current efficiency (IPCE) of the device based on P:PCBM:BTD-TNP shows two distinct bands, which correspond to the absorption bands of P:PCBM and BTD-TNP.

Novel p-phenylenevinylene compounds containing thiophene or anthracene moieties and cyano-vinylene bonds for photovoltaic applications.

Two novel soluble compounds T and A that contain a central dihexyloxy-p-phenylenevinylene unit, intermediate moieties of thiophene or anthracene, respectively, and terminal cyano-vinylene nitrophenyls were synthesized and characterized. They showed moderate thermal stability and relatively low glass transition temperatures. These compounds displayed similar optical properties.

Strong two photon absorption and photophysical properties of symmetrical chromophores with electron accepting edge substituents.

Two photon absorption (TPA) and photophysical properties of three new symmetrical chromophores with electron accepting phthalimide edge substituents have been studied. The three chromophores contain fluorene, alcoxy-substituted divinyl benzene, and carbazole moieties as central cores, respectively. The femtosecond time-resolved fluorescence upconversion spectroscopy and two photon excited fluorescence technique have been carried out.

Synthesis and photophysical characteristics of 2,7-fluorenevinylene-based trimers and their electroluminescence.

Three new 2,7-fluorenevinylene-based trimers were synthesized and characterized. The synthesis was carried out by the Heck coupling reaction of 9,9-dihexyl-2,7-divinylfluorene with 2-(4-bromophenyl)-5-phenyl-1,3,4-oxadiazole, N,N-diphenyl-4-bromoaniline, or 3-bromopyrene to afford the trimers OXD, TPA, and PYR, respectively. All the trimers were readily soluble in common organic solvents such as tetrahydrofuran, dichloromethane, chloroform, and toluene.

Femtosecond time resolved fluorescence dynamics of a cationic water-soluble poly(fluorenevinylene-co-phenylenevinylene).

A recently synthesized cationic water-soluble poly(fluorenevinylene-co-phenylenevinylene) was studied by means of steady state and femtosecond time resolved upconversion spectroscopy in aqueous and EtOH solutions. Steady state spectroscopic measurements showed that the polymer emits at the blue-green spectral region and that aggregates are formed in concentrated polymer solutions. The fluorescence dynamics of the polymer in concentrated solutions, studied at a range of emission wavelengths, exhibited a wavelength dependent and multiexponential decay, indicating the existence of various decay mechanisms.

Substituent effect on the photobleaching of pyrylium salts under ultrashort pulsed illumination.

The current article presents the photobleaching properties of a group of pyrylium salts under ultrashort pulsed illumination. These pyrylium salts have the same basic chemical structure and differ only by a specific substituent. It is proven experimentally that two different mechanisms are simultaneously present to the photobleaching of all molecules studied (independently of their specific chemical structure).