Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Electrical and optical properties of poly͑3-hexylthiophene-2.5diyl͒ ͑P3HT͒ used as the main component in a polymer/fullerene solar cell were studied. From the study of space-charge limited current behavior of indium-tin-oxide ͑ITO͒/P3HT/Au hole-only devices, the hole mobility and density were estimated to range from 1.4ϫ10 Ϫ6 cm 2 /V s and 5.3ϫ10 14 cm Ϫ3 at 150 K to 8.5 ϫ10 Ϫ5 cm 2 /V s and 1.1ϫ10 15 cm Ϫ3 at 250 K, respectively. The highest occupied to lowest occupied molecular orbital energetic difference was estimated from absorption spectrometry to be about 2.14 eV. Strong quenching of photoluminescence when the polymer was mixed with ͓6,6͔-phenyl-C 61 butyric acid methyl ester ͑PCBM͒, provided evidence of photoinduced charge transfer from P3HT to PCBM. Characterization of ITO/PEDOT:PSS/P3HT:PCBM/Al solar cells was done by analyzing the dependence of current density-voltage characteristics on temperature and illumination intensity. The main solar cell characteristics recorded at 300 K under 100 mW/cm 2 white-light intensity were: Open-circuit voltage 0.48 V, current density 1.28 mA/cm 2 , with an efficiency of 0.2%, and fill factor of 30.6%. Open-circuit voltage decreased almost linearly with increasing temperature, while short circuit current density increased with temperature, saturating at around 320 K, and decreased thereafter. Power conversion efficiency and fill factor were maximum around 3 mW/cm 2 due to the poor bulk transport properties of the active layer.

The addition of small amounts of dodecylamine-capped Au nanoparticles into the active layer of organic bulk heterojunction solar cells consisting of poly(3-octylthiophene) (P3OT) and C(60) was recently suggested to have a positive impact on device performance due to improved electron transport. This issue was systematically further investigated in the present work. Different strategies to incorporate colloidally prepared Au nanoparticles with a narrow size distribution into organic solar cells with the more common donor/acceptor system consisting of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C(61)-butyric acid methyl ester (PCBM) were pursued. Au nanoparticles were prepared with either P3HT or dodecylamine as ligands. Additionally, efforts were undertaken to incorporate nearly ligand-free Au nanoparticles into the system. Therefore, a procedure was successfully developed to remove the dodecylamine ligand shell by a postpreparative ligand exchange with pyridine, a much smaller molecule that can later partly be removed from solid films by annealing. However, for all types of nanoparticles studied here, the performance of the P3HT/PCBM solar cells was found to decrease with the Au particles as an additive to the active layer, meaning that adding Au nanoparticles is not a suitable strategy in the case of the P3HT/PCBM system. Possible reasons are discussed on the basis of detailed investigations of the structure, photophysics and charge transport in the system.

Protic organic ionic plastic crystals (POIPCs) are shown to be novel anhydrous solid-state proton conductors for fuel cells.

We report the synthesis of four conjugated copolymers based on alkylated fluorene or phenylene units which band gap is tuned by the regular insertion of an electron-donating or electronwithdrawing unit, (3,4-ethylenedioxy)thiophene and pyridine, respectively. The (AB) n regular sequence is achieved by Suzuki polycondensation reactions. The characterization of the copolymers by size exclusion chromatography reveals chains lengths of about 20-30 repeat units (40-60 rings), leading to a good processability for potential optical applications. The 1:1 ratio between the two units improves the solubility of the material in common organic solvents, allowing for physicochemical characterizations. Raman and FT-IR experiments indicate that the electronic structure of the backbone is rather benzenic in the neutral (undoped) state, as opposed to a quinoic oxidized structure. All copolymers exhibit interesting electrochromic properties as attested by cyclic voltammetry and UV-vis experiments. They reversibly switch among the entire visible spectra, which is of particular importance for display applications. Moreover, the EDOT-based copolymers strongly absorb in the NIR window (1200 nm up to 3000 nm) with some potential electrochromic applications related to this spectral window. Light-emitting diodes were fabricated using these copolymers as active layer. To improve hole and electron injection, the active layer was sandwiched between a ITO/PEDOT:PSSA/copolymer/Ba/Al. The emitting properties were studied on the base of photoluminescence (PL) and electroluminescence (EL) experiments. The spectral emission varies from blue-green to yellow, depending on the composition of the copolymers.

Electrical and optical design and characterisation of regioregular poly(3-hexylthiophene-2,5diyl)/fullerenebased heterojunction polymer solar cells.