Time-evolution of poly(3-hexylthiophene) as an energy relay dye in dye-sensitized solar cells

Energy relay dyes (ERD) and F?rster resonant energy transfer (FRET) are useful techniques for increasing absorption in dye-sensitized solar cells. We use femtosecond transient absorption spectroscopy to monitor charge generation processes in a solid-state DSC containing poly(3-hexylthiophene) (P3HT) as both the hole-transporter and the ERD with a zinc phthalocyanine dye (TT1) as the sensitizer. We observe efficient FRET occurring on picosecond time scales and subsequent hole transfer from TT1 to P3HT occurring onward from 100 ps.     

Charge collection and pore filling in solid-state dye-sensitized solar cells

The solar to electrical power conversion efficiency for dye-sensitized solar cells (DSCs) incorporating a solid-state organic hole-transporter can be over 5%. However, this is for devices significantly thinner than the optical depth of the active composites and by comparison to the liquid electrolyte based DSCs, which exhibit efficiencies in excess of 10%, more than doubling of this efficiency is clearly attainable if all the steps in the photovoltaic process can be optimized. Two issues are currently being addressed by the field. The first aims at enhancing the electron diffusion length by either reducing the charge recombination or enhancing the charge transport rates. This should enable a larger fraction of photogenerated charges to be collected. The second, though less actively investigated, aims to improve the physical composite formation, which in this instance is the infiltration of mesoporous TiO(2) with the organic hole-transporter 2,2',7,7'-tetrakis(N,N-di-p-methoxypheny-amine)-9,9'-spirobifluorene (spiro-MeOTAD). Here, we perform a broad experimental study to elucidate the limiting factors to the solar cell performance. We first investigate the charge transport and recombination in the solid-state dye-sensitized solar cell under realistic working conditions via small perturbation photovoltage and photocurrent decay measurements. From these measurements we deduce that the electron diffusion length near short-circuit is as long as 20?μm. However, at applied biases approaching open-circuit potential under realistic solar conditions, the diffusion length becomes comparable with the film thickness, ～2?μm, illustrating that real losses to open-circuit voltage, fill factor and hence efficiency are occurring due to ineffective charge collection. The long diffusion length near short-circuit, on the other hand, illustrates that another process, separate from ineffective charge collection, is rendering the solar cell less than ideal. We investigate the process of TiO(2) mesopore infiltration with spiro-MeOTAD by examining the cross-sectional images of and performing photo-induced absorption spectroscopy on devices with a range of thickness, infiltrated with spiro-MeOTAD with a range of concentrations. We present our interpretation of the mechanism for material infiltration, and by improving the casting conditions demonstrate efficient charge collection through devices of over 7?μm in thickness. This investigation represents an improvement in our understanding of the limiting factors to the dye-sensitized solar cell. However, much work, focused on composite formation and improved kinetic competition, is required to realize the true potential of this concept.     

Influence of donor moiety in ruthenium sensitizers on the properties of dye-sensitized solar cells

Heteroleptic ruthenium complexes cis-[Ru(H2dcbpy)(L)(NCS)2], where H2dcbpy is 4,4'-dicarboxylic acid-2,2'-bipyridine and L is 4-(4-(N,N-di-(p-hexyloxyphenyl)-amino)styryl)-4'-methyl-2,2'-bipyridine (Rut-A) or 4-(4'-(3,6-dihexyloxycarbazole-9-yl)-styryl)-4'-methyl-2,2'-bipyridine (Rut-B), have been synthesized and characterized by NMR, UV-Vis spectroscopy, and cyclic voltammogram. The effect of different electron donors on the properties of dye-sensitized solar cells has been studied. The power conversion efficiency of DSSC based on Rut-B is 6.1% while Rut-A delivered a lower efficiency of 4.52% under the same device fabrication and measuring conditions. The better photovoltaic performance of Rut-B is mainly associated with enhanced dye absorptivity and charge recombination suppression.     

A perspective on using experiment and theory to identify design principles in dye-sensitized solar cells

Dye-sensitized solar cells (DSCs) have been the subject of wide-ranging studies for many years because of their potential for large-scale manufacturing using roll-to-roll processing allied to their use of earth abundant raw materials. Two main challenges exist for DSC devices to achieve this goal; uplifting device efficiency from the 12 to 14% currently achieved for laboratory-scale ‘hero’ cells and replacement of the widely-used liquid electrolytes which can limit device lifetimes. To increase device efficiency requires optimized dye injection and regeneration, most likely from multiple dyes while replacement of liquid electrolytes requires solid charge transporters (most likely hole transport materials – HTMs). While theoretical and experimental work have both been widely applied to different aspects of DSC research, these approaches are most effective when working in tandem. In this context, this perspective paper considers the key parameters which influence electron transfer processes in DSC devices using one or more dye molecules and how modelling and experimental approaches can work together to optimize electron injection and dye regeneration.     

高分子电解质中锂盐与高分子的相互作用

以共聚氯醚橡胶和丁腈橡胶的溶液共混物为主体 ,含浸 L i Cl O4 / PC液 ,制得两相高分子电解质。用DSC、FT- IR和 X射线衍射法研究了在高分子中的存在状态及其与高分子的相互作用。结果表明 ,L i+主要与 ECO中的醚氧原子配位 ,且被 PC溶剂化 ,L i Cl O4 完全溶解在体系中。亦有少量 L i+与 NBR中的 -CN键发生作用。含浸 L i Cl O4 / PC后 ,ECO/ NBR的相容性提高     

Novel heteroleptic ruthenium (II) complex with DPBPZ derivative for dye-sensitized solar cells

Herein, as Ru(II) complex for the dye-sensitized solar cells (DSSCs), we designed and investigated a novel heteroleptic ruthenium complex [Ru(dcbpy)(dpbpz)(NCS)2] with dpbpz derivative to enhance photovoltaic performance. The density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were used to gain insight into the factors responsible for photovoltaic properties as dye sensitizer. Molecular orbitals analysis confirmed that HOMO of [Ru(dcbpy)2(NCS)2] and [Ru(dcbpy)(dpbpz)(NCS)2] are delocalized over the ruthenium t2g character with sizable contribution from the NCS ligand orbitals. The LUMO of [Ru(dcbpy)2(NCS)2] is localized over the dcbpy moiety. However, LUMO of [Ru(dcbpy)(dpbpz)(NCS)2] is localized over the dpbpz moiety and LUMO + 1 is localized the dcbpy moiety. Overall, the absorption spectrum of the present Ru complex was more broad than that of [Ru(dcbpy)2(NCS)2] known as N3 dye. Especially, absorption band in the region between 500 nm and 600 nm was red-shifted. Moreover, the distance between the HOMO of [Ru(dcbpy)(dpbpz)(NCS)2] and the anchoring moiety is longer than that of [Ru(dcbpy)2(NCS)2]. This means that [Ru(dcbpy)(dpbpz)(NCS)2] have longer charge-separated lifetime than [Ru(dcbpy)2(NCS)2. These results are attributed to the extended pi-conjugation of dpbpz moiety. Therefore, we suggest that newly designed [Ru(dcbpy)(dpbpz)(NCS)2] heteroleptic ruthenium complex would be a good candidate as a dye sensitizer of DSSCs, comparable to [Ru(dcbpy)2(NCS)2].     

Characteristics of dye-sensitized solar cells using natural dye

Dye-sensitized solar cells are expected to be used for future clean energy. Recently, most of the researchers in this field use Ruthenium complex as dye in the dye-sensitized solar cells. However, Ruthenium is a rare metal, so the cost of the Ruthenium complex is very high. In this paper, various dye-sensitized solar cells have been fabricated using natural dye, such as the dye of red-cabbage, curcumin, and red-perilla. As a result, it was found that the conversion efficiency of the solar cell fabricated using the mixture of red-cabbage and curcumin was about 0.6% (light source: halogen lamp), which was larger than that of the solar cells using one kind of dye. It was also found that the conversion efficiency was about 1.0% for the solar cell with the oxide semiconductor film fabricated using polyethylene glycol (PEG) whose molecular weight was 2,000,000 and red-cabbage dye. This indicates that the cost performance (defined by [conversion efficiency]/[cost of dye]) of the latter solar cell (dye: red-cabbage) is larger by more than 50 times than that of the solar cell using Ruthenium complex, even if the effect of the difference between the halogen lamp and the standard light source is taken into account.     

网状聚合物冠醚的压电性能研究

合成了３种网状聚合物冠醚;聚乙二醇双环氧丙基醚,聚一缩二乙二醇双环氧丙基醚和聚二缩三乙二醇双环氧丙基醚。实验表明,ＮＰＣＥ与金属盐络合后具有良好的压电性能,并络合金属直 多,了子价态越高和阴离子体积越小,则压电性能越好,电导率越高。     

Characterization of lithium sulfate as an unsymmetrical-valence salt bridge for the minimization of liquid junction potentials in aqueous-organic solvent mixtures

The transference numbers t of lithium sulfate in acetonitrile/water and methanol/water solvent mixtures have been studied by measuring the emfs of such transference cells as Pb(Hg)|PbSO(4)|Li(2)SO(4) (m(2))||Li(2)SO(4) (m(1))|PbSO(4)| Pb(Hg), Hg|Hg(2)SO(4)|Li(2)SO(4) (m(2))||Li(2)SO(4) (m(1))|Hg(2)SO(4)|Hg, and Li(x)Hg(1-)(x)|Li(2)SO(4) (m(1))||Li(2)SO(4) (m(2))|Li(x)Hg(1-)(x), in view of characterizing Li(2)SO(4) as an unsymmetrical salt bridge for the minimization of liquid junction potentials in potentiometric applications. In water, Li(2)SO(4) is nearly as good a salt bridge as the popular KCl one. Its effectiveness has been verified through the operational pH-metric cell using various aqueous pH(S) standards. In acetonitrile/water solvents of 0.09 mass fraction of acetonitrile at 298.15 K, Li(2)SO(4) shows exact ionic equitransference, obeying the general condition t(+)/z(+) = t(-)/|z(-)|. The Li(2)SO(4) salt bridge can be used either for simple insertion between two different electrolyte solutions to minimize the intervening liquid junction potentials, as the outer component of a double-bridge arrangement of any commonly available reference electrode, or, obviously, for structural incorporation in sulfate-reversible reference electrodes as the appropriate supporting and bridge electrolyte. The operational potential of the Hg| Hg(2)SO(4)|2 m Li(2)SO(4) reference electrode in aqueous solutions is 0.6326 V at 298.15 K.     

Insights into photovoltaic properties of ternary organic solar cells from phase diagrams

The efficiency of ternary organic solar cells relies on the spontaneous establishment of a nanostructured network of donor and acceptor phases during film formation. A fundamental understanding of phase composition and arrangement and correlations to photovoltaic device parameters is of utmost relevance for both science and technology. We demonstrate a general approach to understanding solar cell behavior from simple thermodynamic principles. For two ternary blend systems we construct and model phase diagrams. Details of EQE and solar cell parameters can be understood from the phase behavior. Our blend system is composed of PC₇₀BM, PBDTTT-C and a near-infrared absorbing cyanine dye. Cyanine dyes are accompanied by counterions, which, in a first approximation, do not change the photophysical properties of the dye, but strongly influence the morphology of the ternary blend. We argue that counterion dissociation is responsible for different mixing behavior. For the dye with a hexafluorophosphate counterion a hierarchical morphology develops, the dye phase separates on a large scale from PC₇₀BM and cannot contribute to photocurrent. Differently, a cyanine dye with a TRISPHAT counterion shows partial miscibility with PC₇₀BM. A large two-phase region dictated by the PC₇₀BM: PBDTTT-C mixture is present and the dye greatly contributes to the short-circuit current.     

Integration of polymer electrolytes in dye sensitized solar cells by initiated chemical vapor deposition

The mesoporous titanium dioxide electrode of dye sensitized solar cells (DSSC) has been successfully filled with polymer electrolyte to replace the conventional liquid electrolyte. Polymer electrolyte was directly synthesized and deposited using the initiated chemical vapor deposition (iCVD) process, and an iodide-triiodide redox couple in different redox solvents was then incorporated into the polymer. We have investigated different candidate polymer electrolytes, including poly(2-hydroxyethyl methacrylate) (PHEMA). The open circuit voltage of cells fabricated with iCVD PHEMA was found to be higher when compared with a liquid electrolyte that is attributed to a lower rate of electron recombination.     

Nanoforest Nb2O5 photoanodes for dye-sensitized solar cells by pulsed laser deposition

Vertically aligned bundles of Nb(2)O(5) nanocrystals were fabricated by pulsed laser deposition (PLD) and tested as a photoanode material in dye-sensitized solar cells (DSSC). They were characterized using scanning and transmission electron microscopies, optical absorption spectroscopy (UV-vis), and incident-photon-to-current efficiency (IPCE) experiments. The background gas composition and the thickness of the films were varied to determine the influence of those parameters in the photoanode behavior. An optimal background pressure of oxygen during deposition was found to produce a photoanode structure that both achieves high dye loading and enhanced photoelectrochemical performance. For optimal structures, IPCE values up to 40% and APCE values around 90% were obtained with the N(3) dye and I(3)(-)/I(-) couple in acetonitrile with open circuit voltage of 0.71 V and 2.41% power conversion efficiency.     

染料敏化太阳能电池中凝胶电解质的研究

为提高染料敏化太阳能电-池中电解液的稳定性,对凝胶电解质进行了研究.以1,2-二1甲基-3-丙基咪唑碘(DMPII)作为Ⅰ-源,以3甲氧基丙腈作为溶剂,以偏四氟乙烯一六氟丙烯聚合物(P(VDF-HFP))作为胶凝剂,N-甲基苯并咪唑作为添加剂,制备了凝胶电解质.结果表明,随着电解质中DMPII量及碘量的增加,染料敏化太...     

Liquid Densities, Kinematic Viscosities, and Heat Capacities of Some Ethylene Glycol Dimethyl Ethers at Temperatures from 283.15 to 423.15 K

Liquid densities and heat capacities at 1 MPa, and kinematic viscosities at atmospheric pressure of monoethylene glycol dimethyl ether (MEGDME), diethylene glycol dimethyl ether (DEGDME), triethylene glycol dimethyl ether (TrEGDME), tetrathylene glycol dimethyl ether (TEGDME), pentaethylene glycol dimethyl ether (PeEGDME), and polyethylene glycol 250 dimethyl ether (PEGDME 250) were measured in the temperature range from 283.15 to 423.15 K. For each substance, experimental data were correlated with temperature using empirical polynomial equations. The experimental data were also used to evaluate the predictive capability of some estimation methods of liquid densities and heat capacities for the studied ethylene glycol dimethyl ethers. The densities estimated by the Yen–Woods equation agree with our experimental values with a root-mean-square relative deviation (RMSD) of 3.21% for all ethylene glycol dimethyl ethers. The best estimated results of liquid heat capacities were obtained from the Rowlinson equation based on the corresponding-states principle, with a RMSD of 1.12%. The group-contribution methods give the worst results, especially at high temperatures.     

Extremely thin absorber solar cells based on nanostructured semiconductors

Abstract

Extremely thin absorber (eta) solar cells aim to combine the advantages of using very thin, easily and cheaply produced absorber layers on nanostructured substrates with the stability of all-solid-state solar cells using inorganic absorber layers. The concept of using nanostructured substrates originated from the dye-sensitised solar cell, where having a very high surface area allows the use of very thin layers of dye while still absorbing sufficient sunlight. However, both the dye and liquid electrolyte used in these devices demonstrated poor stability, and efforts were made to replace them with very thin inorganic absorber layers and solid state hole collectors respectively. The combination of these concepts – a nanostructured substrate coated with a very thin inorganic absorber and completed with a solid state hole collector – is known as an eta solar cell. This review summarises the development of both the inorganic absorbers and solid state hole collectors in porous TiO₂ and ZnO nanorod based cells, focusing on the material properties and growth/deposition methods. Future possibilities for eta solar cells are discussed, including utilisation of a wider range of materials, synthesis methods and novel materials such as quantum dots to produce tuned band gap and multijunction solar cells.     

Stable, high-efficiency ionic-liquid-based mesoscopic dye-sensitized solar cells

Efficient and stable mesoscopic dye-sensitized solar cells (DSCs) introducing a low-viscosity binary ionic liquid (1-propyl-3-methyl-imidazolium iodide (PMII) and 1-ethyl-3-methyl-imidazolium tetracyanoborate (EMIB(CN)(4))) electrolyte in combination with a new high-molar-extinction-coefficient ruthenium complex, Ru(2,2'-bipyridine-4,4'-dicarboxylic acid)(4,4'-bis(2-(4-tert-butyloxy -phenyl)ethenyl) -2,2'-bipyridine) (NCS)(2), are demonstrated. The dependence of photovoltaic performance, charge transport and electron lifetime on the composition of the binary ionic-liquid electrolyte with different ratios of PMII/EMIB(CN)(4) were investigated by electrochemical impedance and photovoltage transient techniques. A photovoltaic conversion efficiency of 7.6 % was obtained under simulated full sunlight illumination, which is a record for solvent-free DSCs. These devices exhibit excellent stability at 80 degrees C in the dark or under visible-light soaking at 60 degrees C during 1000 h of accelerated tests.     

ZnO纳米四脚状阵列电极染料敏化太阳能电池

采用化学气相沉积(CVD)法制备了不同尺寸的四脚状纳米ZnO和ZnO纳米棒。采用X射线粉末衍射(XRD)、扫描电子显微镜(SEM)对纳米ZnO的晶型结构和形貌进行表征,研究结果表明CVD法制备的四脚状纳米ZnO具有三维空间结构,其最小平均臂宽约为70nm,臂长约300nm,制备的纳米棒直径约为84nm,长约2μm,且都为六方纤锌矿晶型结构。将ZnO纳米四脚状及纳米棒利用滚涂法在FTO导电玻璃上形成ZnO光阳极,经N719染料敏化后组装成染料敏化太阳能电池,光电性能结果表明,染料敏化小尺寸的四脚状纳米ZnO太阳能电池光电转换效率(η=1.88%)高于染料敏化大尺寸的四脚状纳米ZnO太阳能电池光电转换效率(η=1.18%),远高于染料敏化ZnO纳米棒太阳能电池的光电转换效率(η=0.7%)。     

利用高度稳定的发光薄膜提高多晶硅太阳能电池的光伏效率（英文）

硅基太阳能电池已经主导了整个光伏市场,但是仍然面临着光电转化效率低的问题,其中部分原因是其对紫外线的利用率较低.稀土铕配合物能够将紫外光转化为可见光,有望提高硅基太阳能电池的光电转化效率.然而,这类配合物较低的稳定性限制了它们的实际应用.本文中,我们制备了一种高度稳定的EVA/Eu(ND)4-CTAC发光薄膜,将其覆盖在大尺寸的多晶硅太阳能电池表面(110 cm^2)可以使得光电转化效率从15.06%提高到15.57%.在500 h的加速老化实验中荧光性能几乎没有下降,证明了发光薄膜的超强稳定性.在如此大的有效面积上,发光薄膜使硅基太阳能电池的转换效率提高0.51%的绝对值,同时实现超高的稳定性,说明该发光膜在光伏工业上具有广阔的应用前景.     

Influence of thermal annealing-induced molecular aggregation on film properties and photovoltaic performance of bulk heterojunction solar cells based on a squaraine dye

Squaraine (SQ) dyes have been considered as efficient photoactive materials for organic solar cells. In this work, we purposely controlled the molecular aggregation of an SQ dye, 2,4-bis[4-(N,N-dibutylamino)-2-dihydroxyphenyl] SQ (DBSQ-(OH)₂) in the DBSQ(OH)₂:[6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) blend film by using the thermal annealing method, to study the influence of the molecular aggregation on film properties as well as the photovoltaic performance of DBSQ(OH)₂:PCBM-based bulk heterojunction (BHJ) solar cells. Our results demonstrate that thermal annealing may change the aggregation behavior of DBSQ(OH)₂ in the DBSQ(OH)₂:PCBM film, and thus significantly influence the surface morphology, optical and electrical properties of the blend film, as well as the photovoltaic performance of DBSQ(OH)₂:PCBM BHJ cells.     

硝磷酸腐蚀的CdTe太阳电池性能

CdTe薄膜的腐蚀是制作CdS/CdTe光伏电池的重要技术之一,本实验采用硝磷酸溶液（硝酸1%＋磷酸70%＋去离子水29%）腐蚀CdTe薄膜,通过XRD测试发现在CdTe膜上生成了碲层.随后,在腐蚀后的CdTe薄膜上分别沉积了几种结构的背接触层,并制备出相应结构的CdTe太阳能光伏电池.通过电池的光、暗I-V和C-V特性测试,以ZnTe/ZnTe：Cu/Ni为背接触的小面积太阳电池,其性能优于其它背接触的电池.实验结果表明器件性能与碲的生成和铜的扩散密切相关.