(51) Int. Cl." ........................... H01G 9/20: H01M 14/00; HO1L 31/04 (52) U.S. Cl. .......................... 136/263; 136/252; 429/111; 429/212; 429/213; 257/40; 257/428; 257/431; 257/439; 556/136; 556/137; 544/225; 546/2: 546/8; 54.6/10 (58) Field of Search ..................................... 136/263, 252; 429/111, 212, 213; 257/40, 428,431, 439; 556/136, 137; 544/225; 546/2, 8, 10 (JP) ................................................. 12-064059

Dye-sensitized solar cells (DSSCs) are fabricated using natural sensitizers extracted from rengas ( Gluta spp.) and mengkulang ( Heritieraelata ) wood. The natural sensitizers are extracted using a cold extraction and the Soxhlet extraction methods. This paper presents the results of the analysis of the optical characteristics of the sensitizers via ultraviolet–visible spectrophotometry and Fourier transform infrared spectroscopy. The optical band gap and the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) levels of each investigated sensitizer are calculated on the basis of the analyzed data collected from photoluminescence and cyclic voltammetry. The DSSCs with the mengkulang sensitizer have better conversion efficiency ( ŋ = 0.1695%) than the DSSCs with the rengas sensitizer ( ŋ = 0.109%). The performance of the DSSCs indicates an increment as the ratios of the mixed mengkulang:rengas (60%:40%) and mengkulang:rengas (40%:60%) sensitizers increase up to 0.296 and 0.292%, respectively.

An extremely high conversion efficiency (11.9%) can be achieved for a dye-sensitized solar cell with a ruthenium sensitizer (TUS-38) by optimizing the dye-adsorption conditions and the electrolyte composition.

Solar cell performances of the cosensitized dye-sensitized solar cells (DSCs) with Black dye and D131 using the electrolyte solution containing a quaternary phosphonium iodide with a various alkyl chain length have been evaluated by the photoelectrochemical and the electrochemical impedance spectroscopic measurements. Effects of the difference of the central atom between the quaternary phosphonium iodide and the quaternary ammonium iodide on the solar cell performances have been clarified. The DSC using the electrolyte solution containing tetrabutylphosphonium iodide showed higher Jsc. value and lower Voc and FF values compared to those of the DSC using the electrolyte solution containing tetrabutylammonium iodide. In addition, effects of the alkyl chain length of the quaternary phosphonium iodide on the solar cell performances have been also investigated. The blocking effect of the quaternary phosphonium cation for the access of I3− to the TiO2 surface was found to be improved with increasing the alkyl chain length. The highest conversion efficiency (11.3%) could be obtained in the cosensitized DSC with Black dye and D131 using the electrolyte solution containing a moderate concentration of tetraoctylphosphonium iodide under AM 1.5 (100mW/cm2) irradiation. This study demonstrated that the quaternary phosphonium iodide with a longer alkyl chain is also effective for the improvement of the conversion efficiency of the DSCs due to both the improvement of the electron lifetime in the TiO2 photoelectrode and the slight increment of the conduction band energy of the TiO2.

安価で多機能な色素増感太陽電池(DSC)の効 率(η)は現在 5mm 角セルで 12~13%、1cm 角セ ルの AIST 認証値で 11.9%が最高である。我々 は、ガラス基板サブモジュール DSC で 10%、 フレキシブルプラ基板サブモジュール DSC で 6.5%と世界最高レベルの性能を達成した。(図 3)また、実証研究が NEDO プロで行われている。 二酸化チタン(TiO2)は図 1のDSCの作動機構 からわかるように、光電極として使用され、基 本的には励起色素からの電子を受取り、導電性 基板へ電子を渡す伝導体の役割を果たす。種々 の酸化物が検討されたが、その電子伝導性、色 素とのバンドマッチング、安定性などから、ア ナタース TiO2が最も優れているとされる。 しかし TiO2 光電極の構造により性能は大き く変化する。その具備すべき条件としては、高 表面積、メソポーラス構造、高電導性結晶子、 効率的な光閉じ込め効果、界面での逆反応制御 機能(図 2)などが挙げられる。表1に TiO2光電 極や電解液を最適化した DSC の性能を示す。 TiO2 光電極構造や電解液等の最適化により性 能が大きく変化することがわかる。 DSC の更なる高性能化には、入射光を最大に 利用できるモルフォロジー、TiO2 表面での逆電 子移動(図 1 の(2))の抑制、ナノ粒子の結晶性向 上、TiO2の電子伝導性の向上などが求められる。 本発表では、これらについて議論する。

Three novel metal-free organic dyes (DN458, DN475 and DN484) were designed for use in plastic-substrate dye-sensitized solar cells (PDSCs). The photoelectric conversion region of DN475 was successfully expanded into the near-infrared region. As a result, an energy conversion efficiency of 5.76% was achieved.

A ruthenium sensitizer with an extended π-conjugated terpyridine (TUS-42) has been synthesized for dye-sensitized solar cells (DSCs). Upon extension of the π-conjugated system of the terpyridine ligand, the conversion efficiency of the DSC with TUS-42 improved successfully to 10.7%, which is almost comparable to that of one of the most efficient ruthenium sensitizers (Black dye). Interestingly, an extremely large short-circuit current density (Jsc) value (22.7 mA/cm(2)) was obtained in the DSC with TUS-42 even though the amount of dye adsorption to the TiO2 photoelectrode is relatively small.

The spatial distribution of heterotrophic prokaryotes was investigated during the Tokyo–Palau cruise in the western part of the North Pacific subtropical gyre (NPSG) along a north–south transect between 33.60 and 13.25 N. The cruise was conducted in three different hydrological areas identified as the Kuroshio region, the subtropical gyre area and the transition zone. Two eddies were crossed along the transect: one cold-core cyclonic eddy and one warmcore anticyclonic eddy and distributions of the heterotrophic prokaryotes were recorded. By using analytical flow cytometry and a nucleic acid staining protocol, heterotrophic prokaryotes were discriminated into three subgroups depending on their nucleic acid content (low, high and very high nucleic acid contents labelled LNA, HNA and VHNA, respectively). Statistical analyses performed on the data set showed that LNA, mainly associated with low temperature and low salinity, were dominant in all the hydrological regions. In contrast, HNA distribution seemed to be associated with temperature, salinity, Chl a and silicic acid. A latitudinal increase in the HNA / LNA ratio was observed along the north–south transect and was related to higher phosphate and nitrate concentrations. However, the opposite relationship observed for the VHNA / HNA ratio suggested that the link between nucleic acid content and oligotrophic conditions is not linear, underlying the complexity of the biodiversity in the VHNA, HNA and LNA subgroups. In the Kuroshio Current, it is suggested that the high concentration of heterotrophic prokaryotes observed at station 4 was linked to the path of the cold cyclonic eddy core. In contrast, it is thought that low concentrations of heterotrophic prokaryotes in the warm core of the anticyclonic gyre (Sta. 9) are related to the low nutrient concentrations measured in the seawater column. Our results showed that the high variability between the various heterotrophic prokaryote cluster abundances depend both on the mesoscale structures and the oligotrophic gradient.

Two novel ruthenium sensitizers with a hexylthiophene-modified terpyridine ligand (TUS-35 and TUS-36) were synthesized to improve the molar absorptivity of the previously reported ruthenium sensitizer (TBA)[Ru{4'-(3,4-dicarboxyphenyl)-4,4″-dicarboxyterpyridine}(NCS)3], TBA = tetrabutylammonium (TUS-21). A relatively strong absorption appeared at ∼380 nm, and the molar absorption coefficient at the metal-to-ligand charge transfer (MLCT) band decreased in TUS-35 by introducing a 2-hexylthiophene unit to the 5-position of the terpyridine-derived ligand. For comparison, a relatively strong absorption was observed at ∼350 nm without decreasing the molar absorption coefficient at the MLCT band in TUS-36 by introducing a 2-hexylthiophene unit to the 4-position of the terpyridine-derived ligand. On the other hand, the energy levels of the highest occupied molecular orbitals and the lowest unoccupied molecular orbitals of these two sensitizers were found to be almost equal to those of TUS-21. The adsorption behavior of TUS-35 and TUS-36 was similar to that of (TBA)[Ru{4'-(3,4-dicarboxyphenyl)terpyridine}(NCS)3] (TUS-20), which binds to the TiO2 surface by using the 3,4-dicarboxyphenly unit, rather than that of TUS-21, which adsorbs to the TiO2 photoelectrode using one of the carboxyl groups at the terminal pyridines of the terpyridine-derived ligand. Therefore, TUS-35 and TUS-36 are considered to bind to the TiO2 surface by using the 3,4-dicarboxyphenly unit just like TUS-20. The dye-sensitized solar cells (DSCs) with TUS-35 and TUS-36 showed a relatively lower conversion efficiency (6.4% and 5.7%, respectively) compared to the DSC with TUS-21 (10.2%). Open-circuit photovoltage decay and electrochemical impedance spectroscopy measurements revealed that the promoted charge recombination and/or charge transfer of the injected electrons in the TiO2 photoelectrode is a main reason for the inferior performances of TUS-35 and TUS-36.

Five kinds of electrolyte solutions containing the imidazolium iodide with a different alkyl chain length (DMImI, EMImI, MPImI, DMPImI and HMImI; DMImI=1,3-dimethylimidazolium iodide, EMImI=1-ethyl-3-methylimidazolium iodide, MPImI=1-methyl-3-n-propylimidazolium iodide, DMPImI=1,2-dimethyl-3-n-propylimidazolium iodide, HMImI=1-n-hexyl-3-methylimidazolium iodide) have been prepared to investigate the effects of the alkyl chain length of the imidazolium iodide on the performance of dye-sensitized solar cells (DSCs) with Black dye and D131. The photocurrent density (Jsc) increased and the fill factor (FF) decreased with increasing the alkyl chain length of the imidazolium iodide. Electrochemical impedance spectroscopic measurements of the DSCs revealed that the conduction band energy of TiO2 shifted to the positive direction and the diffusion resistance of the redox couple in the electrolyte solution increased with increasing the alkyl chain length of the imidazolium iodide. Therefore, the observed increment of the Jsc value seems to be attributed mainly to the conduction band energy shift of TiO2, and the observed decrement of the FF value would be caused by increasing the diffusion resistance of the redox couple in the electrolyte solution.The conversion efficiency of the DSCs was found to depend on the ion conductivity of the electrolyte solution, which is closely related to the alkyl chain length of the imidazolium iodide. This study demonstrated that the conversion efficiency could be improved by using EMImI instead of the conventional imidazolium iodide (DMPImI) due to the larger ion conductivity with a slightly higher conduction band energy of TiO2.

Les émotions négatives ressenties au cours de la période diurne, telles que la tristesse, la colère, le regret et le stress, semblent avoir des effets néfastes sur les caractéristiques du sommeil. Par ailleurs, les travaux sur la privation de sommeil suggèrent que le sommeil paradoxal influence la régulation émotionnelle au réveil. Le but de la présente étude était d’explorer les effets d’un état émotionnel (EE), en particulier négatif, induit au coucher, sur la période de sommeil qui suit, ainsi que sur la réactivité émotionnelle au réveil. Douze hommes japonais droitiers (20,5 ± 1,2 ans), volontaires et payés, ont dormi 10 nuits au laboratoire : une nuit de familiarisation suivie de trois sessions de trois nuits consécutives. Chaque session incluait une nuit d’induction émotionnelle (NIE) précédée par une nuit d’adaptation et suivie par une nuit de récupération. L’intervalle entre chaque session était de quatre nuits. Avant le sommeil de la NIE, un EE était induit avec des films positifs, neutres ou négatifs. Au réveil, les participants devaient évaluer l’intensité d’expressions faciales émotionnelles, coléreuses, neutres, ou joyeuses. L’efficacité de l’induction émotionnelle a été mesurée avec la Positive and Negative Affect Scale et le Profile of Mood States. Un polysomnogramme standard a été enregistré. Premièrement, les données psychométriques montrent que les films positif et négatif induisent un EE congruent. Deuxièmement, le film négatif conduit à une augmentation du taux de sommeil paradoxal durant la NIE. Troisièmement, l’intensité subjective de visages coléreux, mesurée au réveil, tend à diminuer après une induction pré-hypnique négative. Ce travail confirme que les films émotionnels peuvent induire des EE de même valence, et qu’ils sont utiles pour caractériser l’impact des EE négatifs sur le sommeil. En outre, il montre, pour la première fois, un impact d’informations négatives pré-hypniques sur la sensibilité aux informations émotionnelles au réveil. Nos données sont compatibles avec l’hypothèse que le sommeil paradoxal module la réactivité émotionnelle au réveil et plaident en faveur d’un rôle adaptatif du sommeil sur la régulation émotionnelle.

A novel ruthenium sensitizer with a terpyridine ligand having a hexylthiophene unit at the 4-position (TUS-38) has been synthesized to investigate the effects of the substituent position on the photo- and electrochemical properties and on solar cell performance. The dye-sensitized solar cell (DSC) with TUS-38 showed a 10.6% conversion efficiency under AM 1.5 (100 mW/cm(2)) irradiation, which is much higher than that of the DSC with a previously reported ruthenium sensitizer with a terpyridine ligand having two hexylthiophene units at the 5- and 5-positions.

Co-sensitized dye-sensitized solar cells using black dye and a pyridine-anchor dye (NI5 or YNI-2) showing site-selective adsorption behaviour at the TiO2 surface have been prepared for the first time to reduce the competitive adsorption between the two dyes.

A novel ruthenium sensitizer ((TBA)[Ru(3',4'-dicarboxyterpyridine)(NCS)3], TBA = tetrabutylammonium, TUS-28) has been synthesized as an improved model sensitizer for (TBA)[Ru(4'-(3,4-dicarboxyphenyl)terpyridine)(NCS)3] (TUS-20). The molar absorptivity of TUS-28 in the whole visible region was smaller than that of TUS-20 due to the absence of the phenyl ring at the terpyridine ligand. On the other hand, the energy levels of HOMO and LUMO of TUS-28 were still suitable for effective electron transfer reactions in dye-sensitized solar cells (DSCs). TUS-28 did not show a superior adsorptivity to the TiO2 surface just like TUS-20, even though TUS-28 has an ortho-dicarboxyl group which is reported to be an efficient anchoring unit. ATR-IR measurements revealed that both carboxyl groups of TUS-28 participate in binding to the TiO2 surface just like TUS-20. Therefore, steric hindrance between the hydrogen atom at the 4-position of 3',4'-dicarboxyterpyridine and the OH group at the TiO2 surface seems to retard the rapid adsorption, and to weaken the binding strength of TUS-28. The DSC with TUS-28 showed 8.2% conversion efficiency, which is higher than that of TUS-20 (7.5%). The J(sc) value of the DSC with TUS-28 was larger than that of TUS-20 even though the amount of dye adsorption of TUS-28 was smaller than that of TUS-20. A more effective electron injection reaction is considered to contribute mainly to the efficiency improvement of TUS-28 since the path length of the electron injection from TUS-28 to the conduction band of the TiO2 is shorter than that of TUS-20 due to the absence of the phenyl ring.

Two novel ruthenium sensitizers having multiple carboxyl groups ((TBA)[Ru{4'-(3,4-dicarboxyphenyl)-4,4″-dicarboxyterpyridine}(NCS)3] (TUS-21) and (TBA)[Ru{4'-(3-carboxyphenyl)-4,4″-dicarboxyterpyridine}(NCS)3] (TUS-37); TBA = tetrabutylammonium) have been synthesized as improved model sensitizers for the previously reported ruthenium sensitizer TUS-20 ((TBA)[Ru{4'-(3,4-dicarboxyphenyl)terpyridine}(NCS)3]). The absorption maxima of two MLCT bands and the absorption onsets of TUS-21 and TUS-37 were shifted to longer wavelengths of about 30 nm in comparison to those of TUS-20 by introducing a carboxyl group to the each terminal pyridine ring of the terpyridine ligand. TUS-21 and TUS-37 showed quite similar adsorption behaviors to the TiO2 surface, and this adsorption behavior was found to be different from that of TUS-20. ATR-IR measurements revealed that TUS-21 and TUS-37 bind to the TiO2 surface by using two carboxyl groups at the 3-position of the phenyl ring and at one of the terminal pyridine rings of the terpyridine ligand, while TUS-20 is reported to bind by using two carboxyl groups at the 3,4-dicarboxyphenyl unit. The dye-sensitized solar cell (DSC) with TUS-21 exhibited 10.2% conversion efficiency, which is much higher than that of the DSC with TUS-20 (7.5%), under AM 1.5 (100 mW/cm(2)) irradiation.

Dependence of the suppression of the backward electron transfer reaction from the TiO2 photoelectrode to I3(-) in the electrolyte on the alkyl chain length of the quaternary ammonium cation has been investigated for further efficiency improvement of high-performance cosensitized dye-sensitized solar cells (DSCs). The tetraheptylammonium cation was found to be more effective than the tetraethylammonium and tetrabutylammonium cations for the suppression of the backward electron transfer reaction without changing the conduction band energy of TiO2. 12.0% conversion efficiency, which is the second highest efficiency for DSCs based on ruthenium sensitizers, was achieved in the cosensitized DSC with Black dye and D131 by using an electrolyte solution containing a moderate concentration of tetraheptylammonium iodide.