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The surface destruction of the ZnO nanorod electrodes occurs in the dye-sensitization process, resulting in the extreme decreases of the short-circuit photocurrent density (JSC), compared to TiO2electrodes. To solve these problems, the TiO2nanolayer is coated on the ZnO nanorod electrodes using a titanium tetrachloride (TiCl4) assisted sonochemical process, which provides faster surface modification. The TiO2nanolayer can form new energy barrier on the ZnO nanorods, which can effectively inhibit the surface charge recombination and improve the energy conversion efficiency of the ZnO nanorod-based dye sensitized solar cells (DSSCs). [ABSTRACT FROM AUTHOR]

In order to improve the P3HT/PCBM polymer photovoltaic devices, C70-PCBM ([6,6]-phenyl C71-butyric acid methyl ester) was employed instead of C60-PCBM ([6,6]-phenyl C61-butyric acid methyl ester). C70-PCBM showed significant increase of visible region light absorption to enhance the photocurrent. To optimize the device performance, we changed the device fabrication conditions such as atmosphere, solvents, post-annealing time, active layer materials composition, and thickness. The best power conversion efficiency of 4.7% was achieved under AM 1.5 G, 75 mA/cm2 condition. [ABSTRACT FROM AUTHOR]

In this article, we fabricated photovoltaic devices based on poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene) (MEH-PPV), as a donor and [6,6]-phenyl C61-butyric acid methyl ester(PCBM) as an electron acceptor materials. The effect of different solvents such as chlorobenzene, o-dichlorobenzene, chloroform, and cosolvent systems prepared with 1:1 ratio of chlorobenzen:o-dichlorobenzene, chlorobenzen:chloroform and o-dichlorobenzene:chloroform on the performance of devices was studied. Further, the effect of a thin electron transport layer of Alq3 inserted between active layer and cathode in the device structure, on the performance of devices was studied with the best solvent. [ABSTRACT FROM AUTHOR]

Two interlayers, blended interlayer based on TPD-oxetane with PFO-TPD-OCH3 and crosslinkable polymer interlayer based on Poly(RO2-spiro-TPA-oxetane), were introduced in polymer light-emitting diodes (PLEDs). Both interlayers showed resistance to organic solvents and the performance of PLEDs was greatly enhanced when each interlayer was inserted. The maximum luminescence efficiency of 0.147 cd/A at 11 V and the maximum luminescence of 739 cd/m2 at 15 V have been achieved with blue light emitting polymer, Poly(RO2-spirobifluorene). [ABSTRACT FROM AUTHOR]

N,N'-Di(1-nonadecyl)perylene-3,4:9,10-bis(dicarboximide) (PDI-C9) based bulk-heterojunction photovoltaic devices increased the power conversion efficiency (PCE) with increasing PDI-C9 concentration and showed the highest incident photon-to-current conversion efficiency (IPCE) of 19% at 495 nm and PCE of 0.18% under AM 1.5 (100 mW/cm2) have been achieved with 1:4 ratio of P3HT: PDI-C9. 1,7-Bis(N-pyrrolidinyl)-N,N'-dicyclohexyl-3,4:9,10-perylenebis(dicarboximide) (5-PDI-DI) based devices showed best performance of 9% IPCE at 525 nm and 0.18% (AM 1.5) PCE at 1:1 blend ratio of P3HT: 5-PDI-DI and the PCEs were drastically decreased by increasing 5-PDI-DI ratio. [ABSTRACT FROM AUTHOR]

Soluble thiophene-based copolymers, poly[(3-alkylthiophene)-co-(3-thiophene acetic acid)]s (P3AT-co-3TAA-n's), were synthesized to apply to the polymer sensitizer of the polymer-sensitized solar cell devices. In order to improve the solubility and the chemical adsorption onto nanoporous TiO2 layers in the polymer-sensitized solar cell devices, thiophene-based copolymers having the chemical structures of the carboxyl group and the alkyl group were designed. We have fabricated solid-state polymer-sensitized solar cell devices using polymer sensitizers and polymer electrolytes, and investigated on the photovoltaic performances. In the polymer-sensitized solar cell devices using polymer sensitizers, Voc is 0.37-0.46 V, Jsc is 0.82-7.71 mA/cm2, and the power conversion efficiency is 0.14-0.38%, respectively. [ABSTRACT FROM AUTHOR]

Chemical oxidative polymerization of 3,3-diheptyl-3,4-dihydro-2H-thieno[3,4-b] [14]dioxepine, (heptyl 2 -PDOT) with iron trichloride (FeCl 3 ) gave the regiosymmetric poly(3,3-diheptyl-3,4-dihydro-2H-thieno[3,4-b] [14] dioxepine), poly(heptyl 2 -PDOT), which has a high glass transition temperature (195°C) and a good solubility behavior in most of common solvents. Electrochemically polymerized one showed higher conductivity at the positively applied potential (1.50 × 10 -2 S/cm at +1.0 V) than the negatively applied one (2.99 × 10 -5 S/cm at -0.3 V). [ABSTRACT FROM AUTHOR]

Three novel alternating copolymers containing 9,9-dioctylfluorene and thiophene derivatives, poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(4,4'-bis(3''-hexyl-2''thienyl)-biphenyl-5”,5''-diyl)] (P1), poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(5,5'-bis(3''-hexyl-2”thienyl)-2,2'-bithiophenyl-5”,5''-diyl)] (P2), and poly[(9,9-dioctylfluorene-2,7-diyl)-alt-(5,5'-bis(3''-hexyl-2''thienyl)-2,2'-biselenophenyl-5”,5''-diyl)] (P3) were synthesized by a palladium-catalyzed Suzuki polymerization. The synthesis, thermal stability, as well as the optical and electrochemical properties of these polymers are systematically investigated. The polymers were thermally stable up to 400°C, and readily soluble in common organic solvent. The absorption and emission maxima of the copolymers varied according to the type of incorporated aromatic group (thiophene, selenophene, or phenylene). [ABSTRACT FROM AUTHOR]

We have fabricated organic solar cells using highly conductive poly 3,4-ethylenedioxythiophene: poly styrenesulfonate (PEDOT:PSS), which are modified by adding 5 wt. -% ethylene glycol (EG) as an anode without using transparent conducting oxide (TCO). The conductivity of the modified PEDOT:PSS (PEDOT:PSS-EG) film with ethylene glycol (EG) additive was enhanced by three orders of magnitude. With the modified PEDOT:PSS film, we investigated the transmittance of visible range light at various film thicknesses and device performance levels on ITO-free organic solar cells-based highly conductive polymer anodes. The power conversion efficiency (PCE) was governed by the series resistance, which directly determines a short circuit current density (Jsc). [ABSTRACT FROM AUTHOR]

In order to confirm the application possibility to the molecular electronic device, the morphological property of arachidic acid (AA) was investigated. We have determined morphology by BAM and AFM. π-A curves investigated surface pressure of this LB film from liquid to solid state ranged between 40 to 45 mN/m. BAM images investigated the different states of AA LB film. When the surface pressure reaches at 40 mN/m, the monolayer was deposited onto the hydrophilic glass substrates by Y-type deposition. We investigated morphological property of arachidic acid by AFM. As a result, we obtained the frequency characteristic and morphology of LB films from controlling the deposited layers. In this paper, I review this subject mainly based on our recent results in merocyanine dye. LB films of merocyanine dye, mixed with arachidic acid, exhibit J-aggregate formation and have been serving as typical systems in revealing the physical and structural aspects of nano-sized molecular aggregates constructed as muiltilayers. [ABSTRACT FROM AUTHOR]

We investigated the electrical and optical properties of single-layered films of indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO) as well as of double-layered ITO/AZO films. These transparent conducting oxide (TCO) films were deposited by sputtering. The ITO/AZO film (500/250 nm thick) had a transmittance slightly higher than that of the ITO film in the visible region, and exhibited slightly lower resistivity than that of the ITO film. These results suggested that photoelectric devices based on double-layered TCO films could be expected to exhibit higher photocurrents. To determine whether this was the case, we used the double-layered ITO/AZO film as the anode electrode in an organic photovoltaic (OPV) cell. The cell was found to exhibit better device performance than that of an OPV cell based on the single-layered ITO film. [ABSTRACT FROM AUTHOR]

In this paper, we fabricated and compared the photovoltaic properties of two different kinds of PEDOT:PSS buffer layer systems. The first was with the PEDOT:PSS buffer layers of different PEDOT to PSS ratios, 1 to 2.5 for Baytron P and 1 to 6 for Baytron PVP AI4083, respectively. The second system included the buffer layers with the same PEDOT to PSS ratio, but with the changed conductivities by doping with 2, 4, 6, 8, and 10 wt% of glycerol. The power conversion efficiency was governed by the series resistance of the device and the resistivity of the applied PEDOT:PSS films, while the parallel resistance and the diode rectification characteristics are affected by the ratio of PEDOT to PSS on buffer layer. [ABSTRACT FROM AUTHOR]

In this article, we report the fabrication of bulk heterojunction photovoltaic devices with combination of three materials. A blend of poly(3-hexylthiophene) (P3HT) and poly(2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylenevinylene) (MEH-PPV) has been used as donor polymer. A fullerene derivative, [6, 6]-phenyl C61-butyric acid methyl ester (PCBM) is used as an electron acceptor material. The donor blend ratio (50:50) is kept constant whereas the ratio of donor to acceptor is varied. The influence of the active layer thickness, and cathode metals on photovoltaic performance has been investigated. The results are compared with the performances of MEH-PPV:PCBM and P3HT:PCBM photovoltaic devices fabricated in similar conditions. [ABSTRACT FROM AUTHOR]

Room temperature ionic liquids have been used as electrolytes to investigate the performance and the characteristics in dye-sensitized solar cells (DSSCs). We focused on quasi-solid state electrolyte using ionic liquids, which are non-volatile liquids having relatively high conductivities. We studied the performance of the DSSC device with different anion or cation structures of ionic liquids. The power conversion efficiency of the DSSC device using [EMIm]+[PF6]- under 100 mA/cm2 is achieved up to 4.37%. [ABSTRACT FROM AUTHOR]

A new class of high brightness and luminance efficiency of poly[2-{4-[5-(3-(3,7-dimethyloctyloxy)phenyl)-1,3,4-oxadiazole-2-yl]phenyl}-1,4-phenylenevinylene] (C10PhOxa-PPV) was synthesized by Gilch polymerization. The weight average molecular weight (Mw) and the polydispersity of C10PhOxa-PPV were found to be 2.7 × 104 and 2.6, respectively. Double-layer light-emitting device with an ITO/PEDOT/C10PhOxa-PPV/Al was fabricated and characterized. The maximum brightness, and luminance efficiency of C10PhOxa-PPV showed values of up to 8.3 cd/A and 4,426 cd/m2, respectively. [ABSTRACT FROM AUTHOR]