Guanidinium Iodides-based Ionic Liquids: Synthesis and Application for Dye-sensitized Solar Cells(DSSCs)

A series of guanidinium ionic liquids（GILs） was designed, synthesized, and used as electrolytes for dye-sensitized solar cells（DSSCs）. The effect of electrolytes containing GILs on the photovoltaic performance of DSSCs was investigated. It is demonstrated that these GILs are promising for being used as electrolytes for DSSCs and a conversion efficiency of 4.1% can be obtained under AM 1.5 sun light irradiation.

Effects of structure and electronic properties of D-π-A organic dyes on photovoltaic performance of dye-sensitized solar cells

Herein,we examine the performance of dye-sensitized solar cells containing five D-π-A organic dyes designed by systematic modification of π-bridge size and geometric structure.Each dye has a simple push-pull structure with a triarylamino group as an electron donor,bithiophene-4,4-dimethyl-4 H-cyclopenta 1,2-b:5,4-b’]dithiophene(M11),4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophenethiophene(M12),thiophene-4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophene(M13),4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophene-benzene(M14),and 4,4-dimethyl-4 H-cyclopenta[1,2-b:5,4-b’]dithiophene(M15)units asπ-bridges,and cyanoacrylic acid as an electron acceptor/anchor.The extension of theπ-bridge linkage favors wide-range absorption but,because of the concomitant molecular volume increase,hinders the efficient adsorption of dyes on the TiO_(2) film surface.Hence,higher loadings are achieved for smaller dye molecules,resulting in(i)a shift of the TiO_(2) conduction band edge to more negative values,(ii)a greater photocurrent,and(iii)suppressed charge recombination between the photoanode and the redox couple in the electrolyte.Consequently,under one-sun equivalent illumination(AM 1.5 G,100 mW/cm^(2)),the highest photovoltage,photocurrent,and conversion efficiency(η=7.19%)are observed for M15,which has the smallest molecular volume among M series dyes.

A new D–D–π–A dye for efficient dye-sensitized solar cells

New metal-free organic dye sensitizers containing mono-triphenylamine or bis-triphenylamine as the electron donor, a thiophene as the π-conjugated system, and a cyanoacrylic acid moiety as the electron acceptor were synthesized. The optical and electrochemical properties of the dyes were investigated,and their performance as sensitizers in solar cells was evaluated. Dye-sensitized solar cells based on dye containing bis-triphenylamine as the electron donor produced a photon-to-current conversion efficiency of 6.06%（Jsc = 14.21 m A/cm;, Voc = 0.62 V, ff = 0.69） under 100 m W/cm;simulated AM 1.5 G solar irradiation（100 m W/cm;）.

Purification of Bipyridyl Ruthenium Dye and Its Application in Dye-Sensitized Solar Cells

Bipyridyl ruthenium dye N3 and N719 was synthesized, purified by the gel chromatogram method and characterized by the proton NMR and UV-Vis spectra. After the purification most of the impurities that decreased the photoelectrochemical properties were removed and the open-circuit voltage （Voc）, short-circuit photocurrent density （Jsc） and overall photo-electric conversion efficiency （η） of the dye-sensitized solar cells （DSCs） increased dramatically. The standard curve of absorbance vs. concentration of N3 and N719 dye was achieved by using UV-Vis quantitative analytic spectrophotometry. This method was employed to determine the concentration of the dye solution after coating of TiO2 films. The linear concentration range of absorbance vs. concentration of N719 was between 6.25×10^-6 mol·L^-1 and 1×10^-4 mol·L^-1 with the molar extinction coefficient （ε） 1.58 ×10^4 L mol·L^-1·cm^-1 at a wavelength of 533 - 531 nm and 1.50 × 10^4 Lmol·L^-1·cm^-1 at a wavelength of 393 - 384 nm , accordingly. The linear concentration range of the N3 dye was 6.25 × 10^-6mol·L^-1 to 1.5× 10^-4 mol·L^-1 with ε of 1.47 × 10^4 L mol·L^-1· cm^-1 at a wavelength of 538 - 535 nm and 1.48 × 10^4 L ·mol·L^-1·cm^-1 at a wavelength of 399 - 393 nm.

Synthesis and photophysical properties of donor–acceptor system based bipyridylporphyrins for dye-sensitized solar cells

Bipyridylporphyrin derivatives possessing a porphyrin moiety as the electron donor and bipyridyl moiety as the electron-acceptor were designed and synthesized for dye-sensitized solar cells （DSSCs）. The photo- physical and electrochemical properties were investigated by absorption spectrometry and cyclic voltam- metry. Density functional theory （DFT） was employed to study electron distribution. From the photovoltaic performance measurements, a maximum conversion efficiency （η） of 0.38% was achieved based on the bipyridylporphyrin ruthenium dye A7 （Jsc = 1.33 mA/cm^2, Voc = 0.45 V, FF = 0.64） under 1,5 irradiation （100 mW/cm^2）.

Photoelectric Characterization of Dye Sensitized Solar Cells Using Natural Dye from Pawpaw Leaf and Flame Tree Flower as Sensitizers

Natural dyes from flame tree flower, Pawpaw leaf and their mixtures were used as sensitizers to fabricate dye-sensitized solar cells (DSSC). The photoelectrochemical performance of the Flame tree flower dye extract showed an open-circuit voltage (VOC) of 0.50 V, short-circuit current density (JSC) of 0.668 mA/cm2, a fill factor (FF) of 0.588 and a conversion efficiency of 0.20%. The conversion efficiency of the DSSCs prepared by pawpaw leaf extract was 0.20%, with VOC of 0.50 V;short-circuit current density, JSC of 0.649 mA/cm2 and FF of 0.605. The conversion efficiency for the flame tree flower and pawpaw leaf dye mixture was 0.27%, with VOC of 0.518 V, JSC of 0.744 mA/cm2 and FF of 0.69. Although the conversion efficiencies, Jsc and the Voc of the prepared dye cells were lower than the respective 1.185%, 7.49 mA/cm2 and 0.64V reported for ruthenium, their fill factors (FF) were higher than that of ruthenium (0.497). It was also observed that both the short-circuit current density and the fill factors of the cells were enhanced using mixed dye.

Plant Seeds-Based Dye-Sensitized Solar Cells

In this work, we investigate the performance of dye-sensitized solar cells (DSSCs) based on natural dyes extracted from ten different plant seeds. The extracts were characterized by UV-VIS absorption spectra. The solar cells were assembled using a TiO2 mesoporous film on FTO-coated glass. The photovoltaic properties of the DSSCs were studied under an incident irradiation of 100 mW/cm2. The best performance was for the DSSC sensitized with Eruca sativa with a solar energy conversion efficiency of 0.725%. Moreover, the validity of these extracts was compared using two types of semiconductor layers (TiO2 and ZnO), and finally the photovoltaic properties of one of these dyes were studied using different types of electrolytes.

The Effect of Electrolyte on Dye Sensitized Solar Cells Using Natural Dye from Mango (<i>M. indica</i>L.) Leaf as Sensitizer

Dye-sensitized solar cells (DSSC) were fabricated with mango leaf dye extracts as natural dye sensitizers at pH value of 5.20 and temperature of 18.1°C. Methanol was used as dye-extracting solvent. DSSCs from dye extract of M. indica L. with KMnO4 electrolyte had the highest photocurrent density of 1.3 mA/cm2 and fill factor FF of 0.46 for the sun at its peak. Potassium permanganate (KMnO4) had a photocurrent density of 1.3 mA/cm2 and FF of 0.8 at sundown. Potassium Iodide (KI), Potassium Bromide (KBr) and Mercury Chloride (HgCl2) electrolytes had 0.2 mA/cm2, 0.08 mA/cm2 and 0.02 mA/cm2 photocurrent densities respectively. The fill factors of 0.09, 0.03 and 0.003 respectively for sun overhead while 0.08 mA/cm2, 0.01 mA/cm2 and 0.01 mA/cm2 were the values of photocurrent densities respectively at sundown. The fill factors were 0.02, 0.0006 and 0.003 respectively at sundown. The maximum power Pmax of the DSSCs were 0.5 mW/cm2, 0.10 mW/cm2, 0.01 mW/cm2 and 0.012 mW/cm2 respectively at 1300 h at 1630 h 0.9 mW/cm2, 0.14 mW/cm2, 0.005 mW/cm2 and 0.0015 mW/cm2 respectively.

Photovoltaic Performance of Triphenylamine Dyes-sensitized Solar Cells Employing Cobalt Redox Shuttle and Influence of π-conjugated Spacers

Developing photosensitizers suitable for the cobalt electrolyte and understanding the structure-property relationship of organic dyes is warranted for the dye-sensitized solar cells （DSSCs）. The DSSCs incorporating tris（1,10-phenanthroline）eobalt（Ⅱ/Ⅲ）-based redox elec- trolyte and four synthesized organic dyes as photosensitizers are described. The photovoltaic performance of these dyes-sensitized solar cells employing the cobalt redox shuttle and the influences of the w-conjugated spacers of organic dyes upon the photovoltage and photocur- rent of mesoscopic titania solar cells are investigated. It is found that organic dyes with thiophene derivates as linkers are suitable for DSSCs employing cobalt electrolytes. DSSCs sensitized with the as-synthesized dyes in combination with the cobalt redox shuttle yield an overall power conversion efficiency of 6.1% under 100 mW/cm2 AM1.5 G illumination.

Effect of Surface Protonation on Device Performance and Dye Stability of Dye-sensitized Ti02 Solar Cell

A flat thin TiO2 film was employed as the photo-electrode of a dye sensitized solar cell （DSSC）, on which only a geometrical mono-layer of dye was attached. The effect of sur- face protonation by HCI chemical treatment on the performance of DSSCs was studied. The results showed that the short-circuit current Jsc increased significantly upon the HCI treatment, while the open-circuit voltage Voc decreased slightly. Compared to the untreated DSSC, the Jsc and energy conversion efficiency was increased by 31% and 25%, respectively, for the 1 mol/L HCI treated cell. TiO2 surface protonation improved electronic coupling between the chemisorbed dye and the TiO2 surface, resulting in an enhanced electron in- jection. The decreased open-circuit voltage after TiO2 surface protonation was mainly due to the TiO2 conduction band edge downshift and was partially caused by increased electron recombination with the electrolyte. In situ Raman degradation study showed that the dye stability was improved after the TiO2 surface protonation. The increased dye stability was contributed by the increased electron injection and electron back reaction with the electrolyte under the open-circuit condition.

Performance Improvement of Dye-Sensitized Solar Cell by Phenanthrothiadiazole Unit-Based π-Conjugated Bridge

New organic dyes (D1, D2, and D3) containing a phenanthrothiadiazole unit as a π-conjugated system, a triarylamine as an electron donor, and a cyanoacrylic acid moiety as an electron acceptor were synthesized. The optical and electrochemical properties of dyes D1, D2, and D3 were investigated, and their performance as sensitizers in solar cells was evaluated. Dye-sensitized solar cells based on dye D3 produced a photon-to-current conversion efficiency of 5.23% (Jsc = 9.70 mA/cm2, Voc = 0.77 V, ff 0.70) under 100 mW/cm2 simulated AM 1.5 G solar irradiation.

Impact of Dye-Sensitized Solar Cell Anode Preparation on Performance

In this paper, the suitable molecular weight of polyethylene glycol (PEG) and annealing temperature for dye-sensitized solar cells (DSSCs) anode was obtained by assessing the performance of DSSCs. The output current characteristic of the DSSCs is to explore factors that affect cell conversion efficiency and the effect of the mechanism. Experimental results show that the annealing temperature of 500&deg;C and adding PEG of molecular weight 2000, the TiO2 thin film electrode TiO2 film electrode has good optical properties.

Characterization of Dye Sensitized Cells Using Natural Dye from Oil Bean Leaf (<i>Pentaclethra macrophylla</i>): The Effect of Dye pH on the Photoelectric Parameters

Fresh leaves of oil bean (P. macrophylla) were used as sensitizers for fabrication of dye sensitized solar cells (DSSCs) at four dye pH values of 2.58°C at 23.7°C, 2.62°C at 22.2°C, 2.65°C at 22.3°C and 3.61°C at 22.1 °C. The methanol extracts of P. macrophylla were extracted and used as sensitizers for the development of dye sensitized solar cells. The solar cells sensitized by P. macrophylla leaf extracts realised up to short circuit current (Jsc) 0.16 mA/cm2, open circuit voltage (Voc) 0.045 V, Pmax 0.031 mW/ cm2 and fill factor (FF) 0.50. The energy conversion efficiency (η) of the DSSCs is 0.43%. Phytochemical screening of P. macrophylla leaf extract shows the presence of flavonoids and anthraquinones. The nanostructured dye shows conversion of solar energy into electricity using low cost natural dyes as wide band-gap semiconductor sensitizers in DSSCs. This will provide economically viable substitute to silicon p-n junction photovoltaic (PV).

Substituent Effect of Chiraldiphenyl Salen Metal （M = Fe（Ⅱ）, Co（Ⅱ）, Ni（Ⅱ）, Cu（Ⅱ）, Zn（Ⅱ）） Complexes for New Conceptual DSSC Dyes

The authors have designed and synthesized new chiral salen-type metal （M = Fe, Co, Ni, Cu, Zn） complexes （1-5） for new conceptual dyes （co-sensitizer or colorful multi-dyes） of DSSCs （dye-sensitized solar cells）. The authors measured substituent effects on their absorption spectra and redox properties, and compared them with TD-DFT （time-dependent density functional theory） calculations. Electron withdrawing groups resulted in red-shift of ultraviolet-visible （UV-Vis） spectra. For the first time, the authors also proposed and confirmed the importance of substituent effects on their electric transition dipole moments, calculated by TD-DFT for designing dyes. Chemisorption for TiO2 of the complex by carboxyl groups was confirmed by XPS measurement. In view of electronic properties, all compounds have the possibility to be dyes of DSSCs.

New D-π-A dyes for efficient dye-sensitized solar cells

Functional organic dyes have promising prospect in dye-sensitized solar cells as a crucial element, of which sensitizers based on donor-π-acceptor are the most important dyes. On the basis of the structures of the aromatic amine donors such as triphenylamine and indoline, this paper reviews the photoelectric conversion properties of organic sensitizers since 2008, and highlights research work in our laboratory in this area.

Recent advances in phenothiazine-based dyes for dye-sensitized solar cells

Dye-sensitized solar cells（DSSCs） have attracted significant attention as alternatives to conventional silicon-based solar cells owing to their low-cost production,facile fabrication,excellent stability and high power conversion efficiency（PCE）.The dye molecule is one of the key components in DSSCs since it significant influence on the PCE,charge separation,light-harvesting,as well as the device stability.Among various dyes,easily tunable phenothiazine-based dyes hold a large proportion and achieve impressive photovoltaic performances.This class of dyes not only has superiorly non-planar butterfly structure but also possesses excellent electron donating ability and large π conjugated system.This review summarized recent developments in the phenothiazine dyes,including small molecule phenothiazine dyes,polymer phenothiazine dyes and phenothiazine dyes for co-sensitization,especially focused on the developments and design concepts of small molecule phenothiazine dyes,as well as the correlation between molecular structures and the photovoltaic performances.

2D-π-A Type Organic Dyes Based on N,N-Dimethylaryl Amine and Rhodamine-3-acetic Acid for Dye-sensitized Solar Cells

Three organic dyes XS17--19 based on N,N-dimethylaryl amine and rhodamine-3-acetic acid moieties are designed and synthesized. These dyes were applied into nanocrystalline TiOa dye-sensitized solar cells through standard operations, showing strong absorption bands at around 320--650 rim, and exhibiting broad IPCE responses. Cell based on XS17 gave a Jsc of 3.7 mA/cm2, an open circuit voltage of 550 mV, and a fill factor of 0.68, corresponding to an overall conversion efficiency of 1.4%. The low overall conversion efficiency is due to the modest IPCE and Voc values, which mainly stem from the acceptor of rhodanine-3-acetic acid.

Ethoxy-substituted Oligo-phenylenevinylene-Bridged Organic Dyes for Efficient Dye-Sensitized Solar Cells

Organic dyes with ethoxy-substituted oligo-phenylenevinylene as chromophores were synthesized for dye-sensitized solar cells （DSSCs）, and the detailed relationships between the dye structures, photophysical properties, electrochemical properties, and performances of DSSCs were described. The dye S3O showed broad IPCE spectra in the spectral range of 350--750 nm, and the dye S1P showed solar energy-to-electricity conversion efficiency （1/） of up to 4.23% under AM 1.5 irradiation （100 mW/cm2） in comparison with the reference Ru-complex （N719 dye） with an r/value of 5.90% under similar experimental conditions.

电沉积法制备DSSCs的CNTs对电极

以碳纳米管(CNTs)为原料,采用电沉积方法制备了染料敏化太阳能电池的对电极。研究了电沉积过程中外加电压、水浴温度、沉积时间对CNTs对电极及其组装电池性能的影响。用扫描电子显微镜对CNTs薄膜的表面形貌进行表征,通过电池的短路电流密度、开路电压、填充因子和光电转换效率等指标来表征CNTs对电极组装电池的性能。结果表明,当外加电压为20V、电沉积时间为10min、水浴温度为65℃时,CNTs对电极组装的电池光电转换性能最佳,为3.77%。

PDDA/CNTs对电极在DSSCs中的应用

对电极是染料敏化太阳能电池(dye-sensitized solar cells,DSSCs)的重要组成部分,将PDDA(poly dimethyl diallyl ammonium chloride)功能化的碳纳米管的复合材料PDDA/CNTs(carbon nanotubes)用作对电极,取代传统的高成本Pt对电极可降低成本。文章用滴加法将复合材料水溶液滴加到导电玻璃基底FTO(fluorine-doped tin oxide)上,制备成对电极薄膜;分析了PDDA/CNTs对电极电池的光电性能及其主要影响因素以及电池的稳定性。该文最优化的电池光电转换效率η和单色光光电转换效率(IPCE)分别达到5.65%和61.6%,相对于纯CNTs对电极组装的电池,其光学性能明显提高。分析结果表明,PDDA/CNTs复合材料是DSSCs中Pt对电极较好的替代品。