Dye-sensitized Nanocrystalline TiO2 Solar Cells Research Articles

Enhancing the Performance of Nanocrystalline TiO2 Dye-Sensitized Solar Cells with Phenothiazine-Doped Blended Solid Polymer Electrolyte

Enhancing the Performance of Nanocrystalline TiO2 Dye-Sensitized Solar Cells with Phenothiazine-Doped Blended Solid Polymer Electrolyte

Efficient dye-sensitized solar cell based on a new porphyrin complex as an inorganic photosensitizer

The synthesis of new porphyrin complexes that can absorb light in a broad range of the spectrum is very important for getting a high efficiency in dye-sensitized solar cells. The primary reason for using these complexes is good photophysical characteristic like good absorption and high quantum efficiency. Most of the metal porphyrin shows good photophysical characteristics with changing their ligands. In this work, the synthesis of a new Zn-porphyrin complex, that has a good spectral and electrochemical characteristic, is reported. Then, this complex is used as a dye in dye-sensitized solar cells, using titanium dioxide as a semiconductor. The application of this complex in a dye-sensitized nanocrystalline TiO2 solar cell has indicated a short circuit density of 11.60 mA, an open circuit potential of 0.65 V with an overall efficiency of 5.33%. The overall conversion efficiency of this system is due to the efficient electron injection into the conduction band during light absorption. In this work, the synthesis of a new Zn-porphyrin complex, together with its spectral and electrochemical properties, is described. The application of this complex in a dye-sensitized nanocrystalline TiO2 solar cell indicated a short circuit density of 11.60 mA, an open circuit potential of 0.65V with an overall efficiency of 5.33%.

Synthesis of new dyes containing double tetrazole groups for sensitization of TiO2 nanoparticles in dye-sensitized solar cells

Di(1H-tetrazol-5-yl)methane is employed as a new electron acceptor group in the synthesis of two metal-free organic dyes containing triphenylamine donor group. Dye-sensitized nanocrystalline TiO2 solar cell (DSSC) applying these novel dyes is constructed for consideration of their photovoltaic properties. The electronic properties of the dyes are also considered with the aid of theoretical calculations. The DSSC constructed from 4-(2,2-di(1H-tetrazol-5-yl)vinyl)-N,N-diphenylaniline (T1) shows a short-circuit photocurrent density of 13.38 mA cm−2, an open circuit voltage of 578 mV, and a fill factor of 0.54, with a resulted solar energy-to-electricity conversion efficiency of 4.18% under simulated 1 sun irradiation (100 mW cm−2). This result reveals that the dye with the di(1H-tetrazol-5-yl)methane anchoring group injects more electrons to the conduction band of TiO2 in comparison with its analogs with single tetrazole ring in their anchoring group. It is found that in spite of a red-shift of the absorption spectrum resulted from the lengthening of the molecule, the dye with two di(1H-tetrazol-5-yl)methane groups gives lower performance than the dye with a single electron acceptor.

Iridium dimer complex for dye sensitized solar cells using electrolyte combinations with different ionic liquids

In this paper, we report the synthesis and characterization of a new cyclometallated iridium complex, [tetrakis(2,2′-bipyridine-4,4′-dicarboxylic acid)(μ-dichloro)diiridium(III)] chloride complex, [(dcbpy)2Ir(μ-Cl)]2Cl4. Four different ionic liquids are also synthesized and characterized for electrolyte combinations. Photovoltaic performance of dye sensitized solar cells have been studied by using four different ionic liquids. The dye sensitized nanocrystalline TiO2 solar cell (DSSC) based on the iridium complex using triethyleneglycol-bis(3-methylimidazolium)diiodide [K36-TFSI] as ionic liquid in electrolyte showed the best photovoltaic performance with a maximum short-circuit photocurrent density (Jsc) of 4.45mAcm−2, an open circuit photovoltage (Voc) of 550mV, and a fill factor (FF) of 0.60, corresponding to an overall conversion efficiency of 1.47% under AM 1.5 sun light.

Zn(II)-porphyrin dyes with several electron acceptor groups linked by vinyl-fluorene or vinyl-thiophene spacers for dye-sensitized solar cells

Herein we report the design, synthesis, and characterization of a series of new organic dyes, as well as their application in dye-sensitized nanocrystalline TiO2 solar cells. In the designed dyes, the diphenylamine Zn(II) porphyrin group plays the role of the core electron donor unit and the cyanoacrylic acid, rhodanine acetic acid, and dicyanorhodanine groups are the acceptors. These electroactive units are linked by either vinyl-fluorene or vinyl-thiophene spacer units. To study the electron distribution and the intramolecular charge transfer the HOMO-LUMO levels of the dyes were calculated by computational methods and experimentally using electrochemical measurements. The DSSCs based on the dyes bearing a cyanoacrylic acid acceptor group showed the best photovoltaic performance with short-circuit photocurrent densities of 12.66 and 13.58 mA/cm2, open-circuit photovoltages of 0.675 and 0.651 V, and fill factors of 0.628 and 0.441, corresponding to an overall conversion efficiency of 5.56 and 4.13%, respectively, under AM 1.5 irradiation (100 mW/cm2).

Synthesis and photovoltaic properties of new [1,2,5]thiadiazolo[3,4-c]pyridine-based organic Broadly absorbing sensitizers for dye-sensitized solar cells

In this paper, by introducing [1,2,5]thiadiazolo[3,4-c]pyridine (PT) as an auxiliary acceptor into the molecular design of organic sensitizers, we have synthesized four new dyes (PT1–PT4) for dye-sensitized solar cells (DSSCs) with triphenylamine or N,N-diphenylthiophen-2-amine as the donor units and thiophene or benzene as the π-bridges, respectively. All the structures, optical and electrochemical properties were fully characterized. Nanocrystalline TiO2 dye-sensitized solar cells were also fabricated using these dyes. Among them, PT2-based DSSCs showed the highest overall conversion efficiency of 6.11% with Voc=668 mV, Jsc=12.61 mA cm−2 and a fill factor (FF)=0.74 after a chenodeoxycholic acid (CDCA) treatment under standard illumination condition (100 mW cm−2 simulated AM 1.5 solar light).

Organic dyes incorporating a thiophene or furan moiety for efficient dye-sensitized solar cells

Four novel carbazole organic dyes containing either a furan or a thiophene unit as the conjugated bridge have been designed, synthesized and characterized for nanocrystalline TiO2 dye-sensitized solar cells. The modified carbazole containing linear or branched alkyl side chain acts as an electron donor, triphenylamine acts as an electron-donating group and cyanoarylic acid acts as an electron acceptor and anchoring unit. The absorption spectra, electrochemical, photovoltaic and sensitizing properties of the new dyes were fully characterized. Among these four dyes, the dye incorporating an octyl-substituted carbazole and disubstituted furan shows the best photovoltaic performance: a maximum monochromatic incident photon-to-current conversion efficiency of 92.4%, a short-circuit photocurrent density of 13.26 mA cm−2, an open-circuit photovoltage of 724 mV, and a fill factor of 0.66, corresponding to an overall conversion efficiency of 6.68% under standard global AM 1.5 solar light condition. The results indicate that the introduction of longer alkyl chain into the carbazole moiety will retard recombination and the introduction of furan as the conjugate bridge will increase the photocurrent response. For comparison, the ruthenium dye, designated as N719, sensitized TiO2 solar cell showed an efficiency of 6.98% under the same experiment conditions.

Dye-sensitized solar cells with natural dyes extracted from rose petals

Nanocrystalline TiO2 dye-sensitized solar cells have been fabricated using TiO2 photoelectrode sensitized using the extracts of red rose and table rose as natural sensitizers and their characteristics have been studied. The extracts having anthocyanin pigment (pelargonidin, peonidin and cyanidin), which have hydroxyl and carboxylic groups in the molecule can attach effectively to the surface of TiO2 film. The solar cell constructed using the red rose sensitized TiO2 photo-electrode exhibited a short-circuit photocurrent of 4.57 mA/cm2 and a power conversion efficiency of 0.81 % and that of table rose sensitized TiO2 photo-electrode exhibited a short-circuit photocurrent of 4.23 mA/cm2 and a power conversion efficiency of 0.67 %. Natural dye sensitized TiO2 photo electrodes present the prospect to be used as an environment-friendly, low-cost alternative system.

A bright entry to improve the performance of DSSCs with the influence of novel optoelectronic acridinedione based macromolecules in I−/I3− electrolytes

The performance of Ru(II) dye-sensitized nanocrystalline TiO2 solar cells (DSSCs) is described with newly synthesized multivalent macromolecules, containing excellent optoelectronic acridinedione linked with 1,2,3-triazole units, via a novel and convenient Cu(I)-catalyzed alkyne and azide 1,3-dipolar cycloaddition (CuAAC) reaction. These unique macromolecules have proved to be highly suitable for utilizing additives in I−/I3− redox couple electrolytes. Among the various substitutions, the maximum photo-current conversion efficiency of about 6.4% with a Voc of 810 mV was obtained with electron rich substitutions in the nitrogen heteroatom.

High Efficiency Dye-Sensitized Solar Cells based on a Bi-Layered Photoanode Made of TiO2 Nanocrystallites and Microspheres with High Thermal Stability

Submicrometer-sized monodispersed TiO2 spheres were synthesized by a controlled hydrolysis of titanium tetraisopropoxide (TTIP) and subsequent solvothermal treatment. The X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–visible spectroscopy analyses revealed that aqueous ammonia concentration and calcining temperature significantly influence the morphology, crystallization, dye loading, and light scattering capacity of TiO2 microspheres. And it was found that the TiO2 microspheres prepared by this method showed a good thermal stability of phase. Bilayered dye-sensitized solar cells (DSSCs) composed of TiO2 microspheres as the scattering cover layers and TiO2 nanocrystallines as the underlayer exhibited a remarkable improvement in the power conversion efficiency (8.25%) compared with the nanocrystalline TiO2 DSSC (6.38%), owing to high light scattering efficiency and the dye-loading capacity of the microsphere cover layer. In addition, electrochemical impedance spectra (EIS) and open-circuit photovoltage decay curves (OCVD) testing indicated that the microsphere cover layer passivated the surface states, increased the density of bulk traps, enlarged the lifetime of electrons, and promoted more efficient charge-transfer, which was also an important reason for the improved power conversion efficiency of double-layered DSSCs.

Electron Transfer in Dye-Sensitized Nanocrystalline TiO2 Solar Cell

The dye-sensitized solar cells (DSSC) have been regarded as one of the most promising new generation solar cells. Tremendous research efforts have been invested to improve the efficiency of solar energy conversion which is generally determined by the light harvesting efficiency, electron injection efficiency and undesirable electron lifetime. In this review, various characteristics of dye- sensitized nanostructured TiO2 solar cells, such as working principle, electron transport and electron lifetime, were studied. The review avoids detailed mathematical and spectroscopic discussion, but rather tries to summarize the key conclusions relevant to materials design.

Pyreno-chalcone dendrimers as an additive in the redox couple of dye-sensitized solar cells

Novel pyreno-chalcone dendrimers 1, 2, and 3 were synthesized and their ability to act as an additive in the redox couple (I−/I3−) of dye-sensitized nanocrystalline TiO2 solar cell has been tested. The redox couple doped with pyreno-chalcone dendrimer 3 gave a short circuit photocurrent density (Jsc) of 7.40 mA/cm2, open circuit voltage (Voc) of 820 mV, and a fill factor of 0.51, corresponding to an overall conversion efficiency (η) of 7.89% under 40 mW/cm2 irradiation.

An organic redox mediator for dye-sensitized solar cells with near unity quantum efficiency

The organic redox mediator tetramethylformaminium disulfide/tetramethylthiourea was evaluated in dye-sensitized nanocrystalline TiO2 solar cells, as an alternative to the conventional I3−/I− redox couple. Devices were optimized by judicious variation of electrolyte composition and selection of sensitizing dye. The best performance of the dye-sensitized solar cells incorporating this redox mediator was achieved by using a metal-free indoline-based sensitizer (D131). It was found that conventional ruthenium based sensitizers (e.g. Z907) exhibited inferior performance, possibly as a result of an insufficient driving force for sensitizer regeneration. A near unity incident photon-to-collected-electron conversion efficiency was achieved at low light intensity for optimized devices. The overall light-to-electric power conversion efficiency under AM 1.5 1 Sun illumination reached 3.88%. This represents an increase of ca. 25% compared with previously reported DSCs using this redox mediator. Factors limiting cell performance were further investigated using transient absorption spectroscopy and electrochemical impedance spectroscopy.

Nanotechnology and Solar Energy

Interest in solar energy conversion and the associated materials research and development has been inspired due to concerns regarding carbon dioxide emissions, job creation, and market instabilities due to the geopolitics and widespread consumption of fossil fuels. The wide introduction of solar powered devices made from nanomaterials has the potential to revolutionize global economic development. Increasing the efficiency and decreasing the costs of solar power are two key areas where nanoscience and nanotechnology can contribute most. Nanotechnology has assumed a special status in semiconductor materials and catalysts. These two classes of materials could be considered as the key for solar energy conversion. Nanomaterials applied in solar energy conversion may be classified depending on their proposed application. Photocatalysts are a big family of nanomaterials (semiconductors or transitionmetal oxides) mostly applied in water treatment and solar water splitting for hydrogen production, among other useful applications. Nanomaterials possess certain desirable properties like high catalytic activity, better stability in aqueous media, comparatively easier preparation techniques, and material economy. Still, nanomaterials suffer from certain drawbacks when they are used in photocatalytic and photoelectrochemical devices. The fascinating optical properties of nanostructured materials find important applications in a number of solar energy utilization schemes and devices. Nanotechnology provides methods for fabrication and use of structures and systems with size corresponding to the wavelength of visible light. This opens a wealth of possibilities to explore the new, often of resonance character, phenomena observed when the object size and the electromagnetic field periodicity (light wavelength λ) match. Titanium dioxide (TiO2) is an n-type semiconductor that has attracted tremendous attention from researchers worldwide due to its potential applications in environmental protection and energy generation. It has demonstrated unique properties such as high adsorption ability and good photocatalytic activity. Dye-sensitized solar cells (DSSCs) are molecular system that consists of TiO2, an anchored molecular photosensitizer, a redox electrolyte, and a platinized photocathode. The sensitizers play a vital role in DSSCs, and a large number of Ru-complex sensitizers and organic sensitizers have been developed and tested. So far, sensitizers such as black dye, N719, and N3 are known as best sensitizers in DSSC. Black dye-sensitized nanocrystalline TiO2 solar cells have been reported to yield a solar to electric power conversion efficiency of over 11% under standard AM 1.5 conditions. Much effort has been made to increase photovoltaic performance (stability) of the DSSCs with the development of new sensitizers, electrodes, and nanostructured photoanode materials. This special issue shows the current trends of research in this branch by presenting two reviews and 14 research articles covering several important areas, ranging from fundamental to applied topics.

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

AbstractThree 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 TiO2 dye‐sensitized solar cells through standard operations, showing strong absorption bands at around 320–650 nm, 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.

Organic Dyes Incorporating Bis-hexapropyltruxeneamino Moiety for Efficient Dye-Sensitized Solar Cells

We report here on the synthesis and photophysical/electrochemical properties of three functional triarylamine organic dyes (MXD5−7) as well as their application in dye-sensitized nanocrystalline TiO2 solar cells (DSSCs). For the designed dyes, the nonplanar structures of bis-hexapropyltruxeneamino take the role of electron donor. The introduction of bis-hexapropyltruxeneamino units brought about superior performance over the simple triphenylamine dye, in terms of light-capturing abilities and suppressing dye aggregation. Among three dyes, the DSSCs based on the dye MXD7 showed the best photovoltaic performance: a short-circuit photocurrent density (JSC) of 11.8 mA cm−2, an open-circuit photovoltage (VOC) of 772 mV, and a fill factor (ff) of 0.68, corresponding to an overall conversion efficiency of 6.18% under 100 mW cm−2 irradiation. These dyes exhibited high VOC values, possible origin for which was investigated regarding the TiO2 surface blocking, conduction band movement, and electrolyte-dye interaction.

PENGGUNAAN EKSTRAK ANTOSIANIN KOL MERAH SEBAGAI FOTOSENSITIZER PADA SEL SURYA TiO2 NANOKRISTAL TERSENSITISASI DYE

The use of Red Cabbage's anthocyanine extract as a photosensitizer on a Dye-Sensitized Nanocrystalline TiO2 Solar Cell. A solid-state dye-sensitized nanocrystalline TiO2 solar cell utilizing anthocyanin extract form red cabbage as photosensitizer was fabricated. The solar cell was formed in sandwich structure, which two electrodes sandwiching polymer electrolyte containing a redox couple (I - /I3 - ). One of the electrodes, namely working electrode, TiO2 layer on TCO (transparent conducting oxide) coated glass substrate was sensitized with anthocyanin dye as electron donor in the system. Another electrode was a carbon sheet as a counter electrode. Gel electrolyte based on PEG (polyethylene glycol) containing a redox couple (I - /I3 - ) used instead of liquid electrolyte in this photoelectrochemical cell. Two fabricated cells have an active area of 1 cm 2 were soaked with anthocyanine dye for 1 hr and 24 hrs, respectively. The

Organic Dyes Containing Thieno[3,2-b]indole Donor for Efficient Dye-Sensitized Solar Cells

Three new organic dyes, comprising thieno[3,2-b]indole moiety as an electron donor, n-hexyl substituted oligothiophene units as a π-conjugated bridge, and cyanoacrylic acid group as an electron acceptor and anchoring group, have been designed and synthesized for nanocrystalline TiO2 dye-sensitized solar cells (DSSCs). Compared with our previous carbazole-based MK dyes, in the similar donor-π-acceptor structure, thieno[3,2-b]indole not only has stronger electron donating ability but also could hold the dye molecule in a more planar conformation than carbazole. The newly synthesized thieno[3,2-b]indole-based dyes exhibit their major electronic absorption in the range of 400−600 nm in the visible region in solution. Solar energy to electricity conversion efficiency (η) up to 7.8% was obtained with a DSSC using 2-cyano-3-[5′′-(4-ethyl-4H-thieno[3,2-b]indol-2-yl)-3′,3′′,4-tri-n-hexyl-[2,2′,5′,2′′]terthiophen-5-yl]acrylic acid (MKZ-40) as light harvesting sensitizer under simulated AM 1.5 G irradiation (100 mW cm−2) with an aperture mask: short-circuit photocurrent density (Jsc) = 14.6 mA cm−2, open-circuit voltage (Voc) = 0.70 V, and fill factor (FF) = 0.76, suggesting that thieno[3,2-b]indole-based organic dyes are promising candidates for DSSCs. However, the DSSCs based on thieno[3,2-b]indole dyes showed shorter electron lifetime compared to that for the solar cell with a conventional carbazole dye, resulting in lower Voc.

N-Aryl Arenedicarboximides as Tunable Panchromatic Dyes for Molecular Solar Cells

Three organic dyes designed as molecular dyads were prepared that feature a common naphthalimide acceptor andN-aryl donors. One of these incorporated an additional cyanoacrylic acid linker and conjugated thiophene bridge inserted between donor and acceptor groups. Electrochemical and photochemical characterizations have been carried out on nanocrystalline TiO2dye-sensitized solar cells which were fabricated with these dyes as the sensitizing component. HOMO and LUMO energies were also calculated using TDDFT methods and validated by the cyclic voltammetry method. A key finding from this study indicates that computational methods can provide energy values in close agreement to experimental for theN-aryl-naphthalimide system. Relative to HOMO/LUMO energy levels ofN719, the dyes based on naphthalimide chromophore are promising candidates for metal-free DSSCs.

Molecular design of organic dyes based on vinylene hexylthiophene bridge for dye-sensitized solar cells

Three donor-(π-spacer)-acceptor (D-π-A) organic dyes, containing different groups (triphenylamine, di(p-tolyl)phenylamine, and 9-octylcarbazole moieties) as electron donors, were designed and synthesized. Nanocrystalline TiO2 dye-sensitized solar cells were fabricated by using these dyes. It was found that the variation of electron donors in the D-π-A dyes played an important role in modifying and tuning photophysical properties of organic dyes. Under standard global AM 1.5 solar condition, the DSSC based on the dye D2 showed the best photovoltaic performance: a short-circuit photocurrent density (Jsc) of 13.93 mA/cm2, an open-circuit photovoltage (Voc) of 0.71 V, and a fill factor (FF) of 0.679, corresponding to solar-to-electric power conversion efficiency (η) of 6.72%.