Dyes For Dye-sensitized Solar Cells Research Articles

Amphiphilic Indoline-Based Unsymmetrical Squaraine Dyes for Dye-Sensitized Solar Cells: Modulating the Dye-TiO2/Electrolyte Interface for Nonaqueous and Aqueous Electrolytes

A high molar extinction coefficient with sharp absorption properties from the range of visible to near-infrared regions makes squaraine dyes very attractive and potential chromophores for dye-sensi...

Performance of TiO2, Cu-TiO2, and N-TiO2 nanoparticles sensitization with natural dyes for dye sensitized solar cells

In this work, the eucalyptus and teak leave extracts are used as natural dyes for dye-sensitized solar cells (DSSCs). The TiO2, copper doped -TiO2 (Cu-TiO2), and nitrogen doped-TiO2 (N-TiO2) nanoparticles were synthesized by using the sol–gel method. The structural, morphological and elemental properties of the prepared samples were tested by X-ray diffractometer (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS). XRD revealed the anatase-TiO2 phase and calculated crystallite sizes are 10, 11.23, and 13.97 nm, correspondingly. SEM micrograph shows the spherical shaped nanoparticles with less agglomeration and primary elements (Ti, O, Cu, N) confirmed by EDS spectra. Further, the nanoparticles used as a photoanode in DSSC device with natural dyes and studied their performance.

Isomeric tetrazole-based organic dyes for dye-sensitized solar cells: Structure-property relationships

Two new organic dyes (SD-1 and SD-2) featured with donor–π–acceptor architecture were synthesized and applied to dye-sensitized solar cells (DSSCs). In these sensitizers, an azo bridge π-spacer is used to link the phenyl tetrazole acceptor with 2-naphthol donors. To amplify the pull-push effect, the nitro group was connected to the electron acceptor group. The effect of the position of the nitro group and the tetrazole group linked to the benzene ring on the photophysical, electrochemical, and photovoltaic properties of sensitizers are investigated in detail. They all show intense UV–Vis absorptions around 400 nm and 510 nm. The co-sensitizations of SD-1 and SD-2 with ruthenium complex HD-2 are further evaluated and the co-sensitization results were compared with DCA. Co-sensitization of HD-2 with SD-2 was more efficient than found for co-sensitization with DCA (5.6% higher). Moreover, the influences of molecular geometry on charge recombination and photovoltaic performance of DSSCs were systematically investigated by incident photon to current efficiency (IPCE) spectra and electrochemical impedance spectroscopy (EIS) investigations.

The role of the π-bridge length in the performance of diketopyrrolopyrrole-based organic dyes for dye-sensitized solar cells

Three novel diketopyrrolopyrrole-based metal-free organic dyes (TPh, BPh and SPh) with different π-bridge lengths were designed and synthesized for dye-sensitized solar cells (DSSCs). The phenyl units were employed as the additional π-bridge for the three dyes, which located between the diketopyrrolopyrrole core and cyanoacrylic acid unit. Interestingly, it is the first time to report a diketopyrrolopyrrole-based dye with only one additional π-bridge unit (SPh). The effects of π-bridge length on photophysical, molecular planarity, energy level and photovoltaic properties of the dyes were systematically investigated. The results revealed that the prolongation of π-bridge length by introducing an additional phenyl unit results in an extra torsion in the structural framework and reduces the molecule planarity, which has a negative impact on improving the light-harvesting ability, while it is beneficial in lowering the tendency of aggregation and enhancing the excited electron injection efficiency. Finally, with a moderate π-bridge length (BPh), the best balance of overall performances is achieved, resulting in the highest power conversion efficiency (6.57%) without chenodeoxycholic acid.

QSPR modeling of absorption maxima of dyes used in dye sensitized solar cells (DSSCs)

Dye-sensitized solar cells (DSSCs) have recently received a significant attention as possible sources of renewable energy. As a result, a significant effort is being made to develop organic dyes for highly power conversion efficient DSSCs, in order to overcome the disadvantages of previous solar cell systems, such as cost reduction, weight reduction, and production methods that minimize environmental pollution. As shown by multiple recent research publications, computational techniques such as quantitative structure–property relationship (QSPR) modeling may aid in the development of suitable dyes for DSSCs satisfying many fundamental desired characteristics. The current report provides robust, externally verified QSPR models for five chemical classes of organic dyes (Triphenylamines, Phenothiazines, Indolines, Porphyrins and Coumarins) based on experimentally determined absorption maxima values. The size of the dye data points utilized to develop the models is the largest known to date. The QSPR models were constructed using only two-dimensional descriptors with clear physicochemical meaning. Using the best subset selection approach, we built 5, 3, 4, 3 and 2 descriptor models for the Triphenylamine, Phenothiazine, Indoline, Porphyrin and Coumarin classes, respectively. The models were validated both internally and externally, and then consensus predictions were made for specific categories of dyes using the developed partial least squares (PLS) models, and the “Intelligent consensus predictor” tool (http://teqip.jdvu.ac.in/QSAR_Tools/) was used to determine whether the quality of test set compound predictions can be improved through the “intelligent” selection of multiple PLS models. We identified from the insights gained from the developed models several chemical attributes that are important in enhancing the absorption maxima. Thus, our study may be utilized to predict the λmax values of novel or untested organic dyes and to give insights that will aid in the development of new dyes for use in solar cells with increased λmax values and enhanced power conversion efficiency.

Organic Dyes in Dye-Sensitized Solar Cells Featuring Back Reflector

Dye-sensitized solar cells (DSSCs) were fabricated using a photoelectrode covered by a porous layer of titanium dioxide, platinum counter electrode, iodide/triiodide electrolyte and three different dyes: phenylfluorone (PF), pyrocatechol violet (PCV) and alizarin (AL). After the adsorption of the dyes on the mesoporous TiO2 layer, the measurement of absorption spectra of all the tested dyes revealed a significant broadening of the absorption range. The positions of highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO) levels of dye molecules were determined, indicating that all three dyes are good candidates for light harvesters in DSSCs. The cells were tested under simulated solar light, and their working parameters were determined. The results showed that the implementation of the back reflector layer made of BaSO4 provided an improvement in the cell efficiency of up to 17.9% for phenylfluorone, 60% for pyrocatechol violet and 21.4% for alizarin dye.

A Molecular Engineering Strategy of Phenylamine-Based Zinc-Porphyrin Dyes for Dye-Sensitized Solar Cells: Synthesis, Characteristics, and Structure–Performance Relationships

A Molecular Engineering Strategy of Phenylamine-Based Zinc-Porphyrin Dyes for Dye-Sensitized Solar Cells: Synthesis, Characteristics, and Structure–Performance Relationships

New isomeric pyridyl imine zinc(II) complexes as potential co-sensitizers for state of the Art N719 dye in DSSC

Three new isomeric Zn(II) complexes derived from pyridine based Schiff bases synthesized by condensation of pyridine-2-carboxyaldehyde and three positional isomers 2-amino pyridine (2-Py-Zn), 3- amino pyridine (3-Py-Zn) and 4-amino pyridine (4-Py-Zn). The synthesized ligands and their Zn(II) complexes have been characterized by microanalyses, FT-IR, multinuclear NMR, UV-Vis and emission spectroscopy. These newly synthesized isomeric complexes have been used as the sensitizers as well as co-sensitizers with state-of-the-art N719 dye in dye sensitized solar cells (DSSCs). Amongst all three isomeric complexes, the DSSC assembly fabricated with 4-Py-Zn/N719 dye shown best performance with an overall photon-to-current conversion efficiency (PCE) of 6.52% with IPCE of 44%. The obtained co-sensitization results are better in comparison to the DSSC fabricated using only N719 (η = 4.22%; IPCE = 45%) under identical condition.

A computational approach on engineering short spacer for carbazole-based dyes for dye-sensitized solar cells

Donor-π-linker-acceptor (D-π-A) push–pull dye molecules are most common in dye-sensitized solar cells (DSSCs) applications. Selection of dye molecules for DSSCs is based on their ability to absorb light in the visible spectrum. This can be done more efficiently by positioning the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) with respect to the conduction band of the semiconductor and the redox potential of the electrolyte, respectively. The photocurrent is manipulated by the extent of light absorption, planarity of the π-linker for efficient intramolecular charge transfer (ICT), oxidized dye reorganization energy (Λ) and dye regeneration driving force (ΔGreg). In a quest of achieving panchromatic absorption up to near-IR region, mostly electron-rich chromophores and their oligo form were used in the π-segment, but this approach led to poor ICT. In this computational analysis, we have explored the effect of electron-withdrawing (cyano (–CN)) and donating groups (methoxy (-OMe)) in three different π-segment length to understand the carbazole dyes’ suitability for DSSCs using onset wavelength (λonset), Λ, ICT and ΔGreg as the figure-of-merits.

First principles design novel D5 derivative dyes with excellent acceptors for highly efficient dye-sensitized solar cells

As the third generation photovoltaic technology, dye-sensitized solar cells (DSSC) use solar energy for photosynthesis like plants. The development of efficient organic dyes in DSSC remains one of the most important scientific challenges. The anchor group has an important influence on the performance of DSSC. A series of metal-free organic D-π-A dye-derivatives (SPL301-SPL307) based on the given D5 were designed using first-principles calculations and their application potential was evaluated in DSSC. The ground state, energy levels and optical properties of a series of organic dyes have been studied by density functional theory (DFT) and time-dependent density functional theory (TD-DFT). These results show that SPL304 is the most promising sensitizer. Then the dyes adsorbed on specific semiconductor, TiO2 (101), are further studied, including the number of injected electrons of the adsorbed dye molecules and the injected electrons of their device components. In this work, we successfully screened the most promising dye-sensitizer SPL304. The adsorption model also shows great performance. The results indicate that among all dyes, SPL304 dye is considered the most promising candidates.

Optical and morphological properties of Curcuma longa dye for dye-sensitized solar cells.

New experimental results of morphological and optical properties of Curcuma longa dye thin film were investigated. The thin films were deposited by physical vapor deposition technique. Morphological properties were measured using atomic force microscopy technique and they show a granular structure which above there are nanotubes shapes. Photoluminescence of Curcuma longa at low temperature was investigated and discussed for the first time. The temperature effect from 77 to 300 K of Curcuma longa thin film has been shown and luminescence was strongly observed. Photoelectrochemical parameters of the dye-sensitized solar cell based on Curcuma longa have been computed via the finite element method. The power conversion efficiency is about 0.86% obtained from short circuit current, open-circuit voltage, and fill factor of 0.13 mA/cm2, 0.52 mV, and 0.83, respectively. As a result, Curcuma longa dye can be applied to dye-sensitized solar cells.

Experimental and theoretical studies of the electrochemical properties of mono azo dyes derived from 2-nitroso-1- naphthol, 1-nitroso-2-naphthol, and C.I disperse yellow 56 commercial dye in dye-sensitized solar cell

Quantum chemical computational tools were used to investigate the charge transfer electron excitation of two mono azo dyes derived from 2-nitroso-1- naphthol, 1-nitroso-2-naphthol, and C.I Disperse Yellow 56 commercial dye. The studied compounds were experimentally synthesized and characterized using UV-Vis and FT-IR spectrophotometry. Theoretical calculations were conducted with the synthesized dyes using density functional theory (DFT) and time-dependent DFT with 6-311+G(d,p) basis set in acetone, chloroform, DMSO, ethanol, gas, and water respectively. The solvent model (CPCM) is used in the calculations. The photovoltaic properties of the studied compounds were analyzed in terms of open-circuit voltage (Voc), electron injection, light-harvesting efficiency (LHE), HOMO-LUMO, and energy gap. The highest oscillator strength transition is observed at the HOMO–LUMO region of all the studied dyes molecules at 0.0534, 0.0012, 0.0048, 0.0543, 0.0542, 0.0024, 0.0074, 0.0534, 0.4903, 0.0531 for dye DA, DB, and DC in the various solvents respectively. Dye DC and DB gave the highest energy gap in acetone, DMSO, ethanol, gas, water, and chloroform media respectively. Interestingly, the LHE of the dyes was high in all the solvents used with the highest result obtained in acetone at 0.7308 for dye DC. The ∆Greg varies between -10.5 eV to11.8 eV in all the studied solvents which indicates a high electron injection capacity within the studied dyed molecules. The open-circuit voltage Voc, the ΔGinject and ΔGreg values for the selected molecule play a vital role in the comparison of both the selected dyes and thus they can be regarded as promising molecules for application in dye-sensitized solar cells.

Electronic and optical properties’ tuning of phenoxazine-based D-A2-π-A1 organic dyes for dye-sensitized solar cells. DFT/TDDFT investigations

Modulation of molecular features of metal free organic dyes is important to present sensitizers with competing electronic and optical properties for dye sensitized solar cells (DSSCs). The D-A2-π-A1 molecular design based on phenothiazine skeleton (D) connected with benzothiadiazole (A2) linked with furan π-spacer and acceptor unit of cynoacrylic acid (A1) were fabricated and examined theoretically for possible use as DSSCs. Density functional theory (DFT) and time dependent density functional theory TDDFT were used to study the effect of additional donors on the photophysical properties of the dyes. Eight (8) different donor subunits were introduced at C7 of phenoxazine based dye skeleton to extend the π-conjugation, lower HOMO-LUMO gap (Eg) and improve photo-current efficiency of the dye sensitizer. All the dye sensitizers (except P3 and P4) exhibited capability of injecting electrons into the conduction band of the semiconductor (TiO2) and regenerated via redox potential (I−/I3-) electrode. Attachment of 2-hexylthiophene (P2) remarkably lowered the Eg, extended π-electron delocalization, hence, gives higher absorption wavelength (λmax) at 752 nm. The donor subunit containing 2-hexylthiophene (P2) presented the best chemical hardness, open circuit voltage (Voc), and other comparable electronic properties, making P2 the best DSSC candidate amongst the optimized dyes. The reported dyes would be interesting for further experimental research.

Analysis of Absorbance Patterns and Functional Groups of BIO-Dye (<i>Ocimum sanctum</i>) Based on pH Variations in the Wet and Dry Extraction Method

Bio-Dye is a dye derived from natural ingredients that have an important role in DSSC performance. This Bio-Dye is later in charge of absorbing sunlight entering the DSSC cells. Bio-Dye is a dye derived from natural ingredients that have an important role in the performance of the DSSC. This Bio-Dye is the one that will be in charge of absorbing sunlight entering the DSSC cells). One important key to know DSSC performance is to pay attention to the quality of the BIO-Dye. A good BIO-Dye can be seen by knowing the absorbance pattern and the function group of the dye its self. This research was conducted to determine absorbance patterns and functional groups based on pH variations in the wet and dry extraction methods contained in the Ocimum sanctum. The absorbance pattern was seen using a UV-Vis spectrophotometer and a functional group using FTIR. The chlorophyll pigment contained in the BIO-Dye (Ocimum sanctum leaf) was extracted using an ethanol solvent and added acetic acid to produce variations in pH values. The UV-Vis spectrometer measurement results showed the highest absorbance pattern was possessed by Ocimum sanctum dye in the dry extraction method and at natural pH (pH = 6.5). The peak absorbance they have is 648 nm, 614 nm, and 537 nm. The FTIR spectrum was obtained from Ocimum sanctum information containing the same functional groups when variations in pH values ​​were carried out in the wet and dry extraction methods. The functional groups are OH groups at wave number 3356.57 cm-1, CH at 2975.37 cm-1, C = O at 1652.50 cm-1, CN at 1383.81 cm-1, C = C at 880.25 cm-1, and CH absorbed at wave number 1087.78 cm-1. In general, it can be concluded that natural dye from Ocimum sanctum has a high absorbance in the visible light region and contains COOH compounds that can strengthen the bond of dye with TiO2 semiconductors so that Ocimum sanctum can be used as a dye in Dye-Sensitized Solar Cells (DSSC).

Comparative Studies on the Structure-Performance Relationships of Phenothiazine-Based Organic Dyes for Dye-Sensitized Solar Cells.

A D–A−π–A dye (PTZ-5) has been synthesized by introducing a benzothiadiazole (BTD) unit as an auxiliary acceptor in a phenothiazine-based D−π–A dye(PTZ-3) to broaden its spectral response range and improve the device performance. Photophysical properties indicate that the inclusion of BTD in the PTZ-5 effectively red-shifted the absorption spectra by reducing the Egap. However, the device measurements show that the open-circuit voltage (Voc) of PTZ-5 cell (640 mV) is obviously lower than that of the PTZ-3 cell (710 mV). This results in a poor photoelectric conversion efficiency (PCE) (4.43%) compared to that of PTZ-3 cell (5.53%). Through further comparative analysis, we found that the introduction of BTD increases the dihedral angle between the D and A unit, which can reduce the efficiency of intramolecular charge transfer (ICT), lead to a less qCT and lower molar extinction coefficient of PTZ-5. In addition, the ESI test found that the lifetime of the electrons in the PTZ-5 cell is shorter. These are the main factors for the above unexpected result of PCE. Our studies bring new insights into the development of phenothiazine-based highly efficient dye-sensitized solar cells (DSSCs).

Treatment of the ZnO and TiO2 Thin Films by Electric Field in Plasma Sheath to Improve the Metal-Dye Electronic Coupling in Dye-Sensitized Solar Cells

In this study, the effect of the electric field of Ar and N2 plasma sheath on the crystalline structure and the optoelectronic properties of ZnO and TiO2 thin films were investigated, in order to improve the electronic coupling of metal-N719 dye in dye-sensitized solar cells. The thin films were prepared via the sol-gel method and then treated in Ar and N2 glow discharge plasma. The plasma effect on the crystalline structure was determined using the XRD spectra and the scanning electron microscope images. The electric field in the Ar plasma sheath is stronger than the N2 plasma, so the crystalline changes in the ZnO/Ar and TiO2/Ar were larger in comparison to ZnO/N2 and TiO2/N2. The variations evaluated via the UV-VIS spectra for the optoelectronic properties coincided with the changes in the crystalline structure. A detailed study of the dispersion parameters and the third-order nonlinear optical susceptibilities represented alterations in the chemical properties of the surface of the thin films.The thin films of ZnO, ZnO/Ar, ZnO/N2, TiO2, TiO2/Ar, and TiO2/N2 were sensitized by the N719 dye via the immersion method, with enough duration of time for the adsorption and the aggregation to take place. According to the measurements of the short circuit photocurrent density, the order of enhancement in the electronic coupling is: ZnO/Ar-N719> ZnO/N2-N719> TiO2/Ar-N719> TiO2/N2-N719. The plasma remarkably enhances the Zn-N719 electronic coupling via the reduction of the Zn2+/dye complexes, in the case of the Ti-N719, increment in the electronic coupling occurs by the reduction of the H-bonds.

Influence of various dithienoheterocycles as conjugated linker in Naphtho[2,3-d] [1,2,3]triazole-based organic dyes for dye-sensitized solar cells

Three metal-free sensitizers HJL-1−HJL-3 based on the D-A′-π-A structure configuration incorporating electron-deficient naphtho[2,3-d] [1,2,3]triazole (NTz) as the conjugation spacer, various dithienoheterocycles as π linkers, were developed and used as the photosensitizers in dye-sensitized solar cells (DSSCs). The results indicate that all of the three dyes exhibit strong light-capturing ability in the visible region and obtain relatively high molar extinction coefficients (> 40000 M−1 cm−1) due to their strong charge transfer (CT) from donor to acceptor. Under standard global AM 1.5 G illumination, the DSSCs performance from these dyes exhibited conversion efficiencies ranging from 5.85% to 6.91%. After coadsorbed with CDCA, the DSSCs based on HJL-3 dyes gives 7.17%, which is about 95% of the N719-based standard cell.

Conjugating pillararene dye in dye-sensitized solar cells

Summary The improvement of open-circuit voltage (VOC) is a crucial goal to develop efficient dye-sensitized solar cells (DSSCs). Here, conjugating pillar[5]arene dyes (PPI and PPII) are designed, synthesized, and applied in DSSCs. The presence of pillar[5]arene moiety in the dyes inhibits the dye aggregation and charge recombination in the DSSCs, leading to the enhancement of VOC. PPI with a single D-π-A backbone and a pillar[5]arene moiety achieves a VOC of 715 mV, which is much higher than the reference dye (VOC of 674 mV) with the same D-π-A backbone but no pillar[5]arene moiety. PPII with 2 D-π-A backbones also achieves a VOC of 746 mV and a much higher short-circuit photocurrent (JSC) than the reference dyes. In addition, the host-guest interaction can adjust the VOC and JSC by coupling dye with the imidazolium in electrolyte, as confirmed by the electrolyte engineering.

Dye extracted from Costus woodsonii leave as a natural sensitizer for dye-sensitized solar cell

Current work employs dye extracted from leaves of Costus woodsonii as a new sensitizer for dye-sensitized solar cells (DSSCs). The leave was extracted in three different solvents namely ethanol, methanol, and acetone. Extraction of leaves was carried out by the freezing method. DSSCs with the configuration of TiO2/dye/electrolyte/Pt were assembled. The dyes in DSSCs were Costus woodsonii leaves extracted in methanol, ethanol, and acetone. DSSC with methanol extract of leaves has an efficiency of 0.23 % and short-circuit current density (Jsc) of 0.63 mA cm-2. DSSC sensitized with ethanol extract of leaves has an efficiency of 0.37 % and Jsc of 0.85 mA cm-2. DSSC sensitized with acetone extract of leaves shows the highest efficiency of 0.48 % and Jsc of 1.35 mA cm-2. The performance of the DSSCs in this work is compared with other natural dye-based DSSCs. The efficiency obtained in this work is better or at par with the works reported by other researchers.
 Keywords: Natural dye; Costus woodsonii; Leave; Dye-sensitized solar cells

Efficient tuning of zinc phthalocyanine-based dyes for dye-sensitized solar cells: a detailed DFT study.

The growing energy demand speed up the designing of competent photovoltaic materials. Herein, five zinc phthalocyanine-based donor materials T1–T5 are designed by substituting various groups (isopropoxy, cyano, fluoro, methoxycarbonyl, and dicyanomethyl) around zinc phthalocyanine. B3LYP/6-31G (d,p) level density functional theory (DFT) was used to investigate the optoelectronic properties of five zinc phthalocyanine-based dyes T1–T5 for dye-sensitized solar cells. The designed molecule T1 shows maximum absorption wavelength (λmax) in the absorption spectrum at 708.89 and 751.88 nm both in gaseous state and in THF (tetrahydrofuran) solvent. The Eg value of T1 (1.86 eV) is less than reference R, indicating a greater charge transfer rate for T1 among the molecules. The values of open-circuit voltages achieved with acceptor polymer PC71BM are higher than R except for T1 and are 0.69 V, 1.95 V, 1.20 V, 1.44 V, and 1.84 V for T1, T2, T3, T4, and T5, respectively. The lower the reorganization energy, the higher the charge transfer for T1 due to its lower hole mobility (0.06297 eV) than R. Thus, the designed T1–T5 molecules are expected to exhibit superior performance in dye-sensitized solar cells.