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To investigate the substituent effects introduced into oligothiophene units, a series of novel donor–acceptor conjugated polymers containing ester-substituted oligothiophenes were synthesized by the direct C–H arylation polycondensation of bis(ester-substituted thienyl)benzothiadiazole and dibromo-substituted oligothiophenes. The ultraviolet–visible absorption spectra of three polymers showed two absorption bands in the visible light wavelength region, ascribed to π–π* transition and the intramolecular charge transfer bands. The oxidation potentials of the polymers exhibited a negative shift with an increase in the chain length of the oligothiophene units. By comparing these polymers with alkyl-substituted analogues, it was found that the introduction of electron-withdrawing ester groups induced a negative shift in the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels and affected the LUMO rather than the HOMO energy levels. As a preliminary experiment, organic photovoltaic cells using these polymers were prepared, and their photoelectric conversion characteristics were investigated in relation to their chemical structures. [ABSTRACT FROM AUTHOR]

As a new class of D–π–A dye sensitizer for dye-sensitized solar cells (DSSCs), we have designed and synthesized the functionally separated D–π–A fluorescent dye YJY-1 with an aldehyde as an electron-accepting group and a carboxyl group as an anchoring group. Furthermore, not only to evaluate the usefulness of D–π–A dye sensitizers functionally separated into an electron acceptor moiety and an anchoring group, but also to gain insight into the influences of interaction between the aldehyde of the dyes and the TiO2 surface on the photovoltaic performances of DSSCs, the D–π–A fluorescent dye YJY-2 with an aldehyde as an electron-accepting group, but without a carboxyl group, was also synthesized. It was found that the functionally separated D–π–A dye YJY-1 exhibits not only high adsorption ability onto TiO2 film through the carboxyl group, but also efficient electron injection from the dye into the CB of TiO2 through the aldehyde which is located close to the TiO2 surface. This work demonstrates that the functionally separated D–π–A dyes would be expected to be one of the most promising classes of organic dye sensitizers for DSSCs. [ABSTRACT FROM AUTHOR]

D–π–A type boron dipyrromethene (BODIPY) dye YH-1, which has two pyridyl groups as electron-withdrawing-anchoring groups at the end of the 3- and 5-positions and a carbazole-diphenylamine moiety as an electron donor at the 8-position on the BODIPY core, was designed and developed as a photosensitizer for dye-sensitized solar cells (DSSCs). It was found that the dye YH-1 possesses a good light-harvesting efficiency (LHE) in the red/near-IR (NIR) region and good adsorption ability on TiO2 film. We demonstrate that the expansion of the π-conjugated system by the introduction of not only the carbazole-diphenylamine moiety and the thiophene unit at the 8-position but also two thienylpyridines at the 3- and 5-positions on the BODIPY core can lead to red-shift and broadening of the absorption band in the red/NIR region. DSSCs based on YH-1 exhibit incident photon-to-current conversion efficiency of ca. 10% over a range of 500 to 700 nm, with an onset at 800 nm. [ABSTRACT FROM AUTHOR]

The triads (nT-2C60) consisting of one oligothiophene and two fullerenes have been synthesized as single-component materials for photovoltaic cells. The sandwich-type cells of a configuration A1/nT-2C60/Au generate much higher photocurrents than those based on the oligothiophene-fullerene dyads (nT-C60). [ABSTRACT FROM AUTHOR]

Investigates the potential of oligothiopene/fullerene dyads as photovoltaic cells. Performance characteristics of the photovoltaic devices; Schematic structure of dyad-based photovoltaic cell; Percentage of monochromatic power conversion efficiency of a photovoltaic cell.

Electric and photovoltaic characteristics of an orgainic p-n junction photovoltaic cell are described, where the p-type and n-type compounds used are phthalocyaninatozinc (II) (ZnPc) and 5, 10, 15, 20 -tetra (3-pyridyl) porphyrin (TPyP), respectively. The p-n junction cell with a thin film of TPyP exhibited stronger spectral sensitization and better spectral match to a solar spectrum than the Schottky barrier cells using either TPyP and ZnPc. The energy conversion efficiency found was about 2% for monochromatic light at 430 nm. [ABSTRACT FROM AUTHOR]

Novel tetrathiafulvalene-oligothiophene-fullerene triads have been synthesized as single-component materials for photovoltaic cells. They showed somewhat improved photovoltaic performances, when compared to the corresponding oligothiophene-fullerene dyads. [ABSTRACT FROM AUTHOR]

A novel panchromatic donor-π-acceptor (D-π-A) dye composed of oligothiophene having 3,4-ethylenedioxythiophene (EDOT) as a π-linker and the bulky group on the triarylamine donor unit has been synthesized, and its photovoltaic performances were compared with those of dye without bulky group. It was found that the introduction of bulky substituent at the donor unit improved the electron injection efficiency from dye to TiO 2 electrode, leading to the enhancement of the short-circuit current ( J sc ). Also, the bulky substituent suppressed the dark current from TiO 2 to the redox electrolyte, which improved the open-circuit voltage ( V oc ). [ABSTRACT FROM AUTHOR]

Highlights: [•] We synthesize three types of copolymers and investigate their properties. [•] Three copolymers are compared with our previous main-chain type copolymer. [•] Highest power conversion efficiency reaches 4.49%. [•] Conjugated side-chain with an electron-deficient group enhances the performance. [Copyright &y& Elsevier]

Abstract: Novel copolymers (P1 and P2) comprising (E)-2,3-bis(2-thienyl)acrylonitrile and benzo[1,2-b;4,5-b′]dithiophene derivatives are designed and synthesized to be applied as an electron donor material in polymer solar cells blended with PC61BM as an electron acceptor. These copolymers show a good thermal stability with a 5% weight loss temperature beyond 340°C, and their films exhibit a broad absorption band with a low optical bandgap of ca. 1.84eV. Polymer solar cells based on P2, prepared under optimized preparation conditions, are found to exhibit a short-circuit photocurrent of 10.71mAcm−2, an open-circuit photovoltage of 600mV, a fill factor of 65%, and a power conversion efficiency of 4.17% under AM 1.5 illumination conditions, 100mWcm−2. [Copyright &y& Elsevier]

Abstract: New-type donor–acceptor π-conjugated benzofuro[2,3-c]oxazolo[4,5-a]carbazole fluorescent dyes with various lengths of non-conjugated alkyl chains containing a carboxyl group at the end position have been developed and their photovoltaic performances of dye-sensitized solar cells are investigated. It is found that in spite of the lengths of the alkyl chains, due to flexibility of alkyl chain, the cyano group of the dyes is located in close proximity to TiO2 surface and thus a good electron communication between the dyes and TiO2 surface is established. [Copyright &y& Elsevier]