Photosensitizers For Dye-sensitized Solar Cells Research Articles

Low-cost Schiff bases chromophores as efficient co-sensitizers for MH-13 in dye-sensitized solar cells

Herein, we reported on the synthesis of four Schiff bases (S1–4) based on salicylaldehyde moieties and their applications as metal-free organic chromophores for sensitization and co-sensitization of dye-sensitized solar cells (DSSCs). These sensitizers are comprised of a phenyl ring as a donor scaffold connected with a carboxylic group as acceptor/anchoring unit. To gauge their applicability as photosensitizers for DSSCs the photophysical, electrochemical, theoretical studies and charge transport characteristics were carried out. Interestingly, uses of S2 and S4 dyes as co-sensitizers with well-known MH-13 dye resulted in enhancing its photovoltaic properties from 8.217 to 8.79% and 8.48%, respectively. Furthermore, the photo-sensitizer S3 individually shows better photovoltaic properties compared to S1, S2 and S4, due to the fast photo-induced electron transfer from the phenyl ring to the nitro group. This fast electron transfer resulted from the overlapping between HOMO and LUMO levels on phenyl ring bearing nitro group. The results indicate that these simple and easy prepared Schiff bases moieties may be considered as promising and low-cost co-sensitizers for DSSCs.

Direct comparison of dithienosilole and dithienogermole as π-conjugated linkers in photosensitizers for dye-sensitized solar cells.

Dithienosilole (DTS) and dithienogermole (DTG) are useful building units of π-conjugated organic materials. In the present work, donor-π-acceptor (D-π-A) dyes with bis(dihexyloxyphenyl)aminophenyl, DTS or DTG, and pyridine or cyanoacrylic acid as the donor (D), the π-conjugated linker (π), and the acceptor (A) units, respectively, were prepared and their optical properties were investigated. The D-π-A dyes exhibited strong absorption in the visible region, indicating efficient intramolecular donor-acceptor interaction. The addition of trifluoroacetic acid to solutions of pyridine-containing dyes led to red-shifts of the absorption bands as a result of pyridinium salt formation. Similar red-shifts were observed for cyanoacrylic acid dyes, which were due to the enhanced formation of neutral dyes relative to the separated ion pairs. The D-π-A dyes, however, showed similar absorption spectra when attached to the TiO2 surface, indicating that the dye-TiO2 electronic interaction was rather weak. In contrast to the finding that these dyes exhibited similar optical properties regardless of the π-linker (i.e., DTS or DTG), dye-sensitized solar cells (DSSCs) based on DTG-containing dyes exhibited superior performance compared to those based on DTS-containing dyes. Electrochemical impedance spectroscopy measurements supported the higher performance of the DSSCs with DTG-containing dyes.

Triarylamine-based hydrido-carboxylate rhenium(i) complexes as photosensitizers for dye-sensitized solar cells.

Two new dyes based on a dinuclear rhenium complex and (E)-3-(5-(4-(bis(2',4'-dibutoxy-[1,1'-biphenyl]-4-yl)amino)phenyl)thiophen-2-yl)-2-cyanoacrylic acid (namely D35) have been investigated as sensitizers for dye sensitized solar cells (DSSCs). Two different pyridazine ligands have been used, namely 4-pyridazine-carboxylic acid for dye 2 ([Re2(μ-H)(-D35)(CO)6(μ-pyridazine-4-COOH)]) and 4-pyridazinyl-butanoic acid for dye 3 ([Re2(μ-H)(-D35)(CO)6(μ-pyridazine-4-C3H6-COOH)]). The performances of these new dyes have been compared with those of the dye containing the bare 4-diphenylaminobenzoic acid, namely TPA, as the ancillary ligand (dye 1). Compared to dye 1, dyes 2 and 3 show an impressive tenfold increase in the absorption intensity in the range of 487-493 nm on TiO2 films, with great improvement of the light harvesting. Cyclic voltammetry experiments, performed on derivatives containing the methyl ester of the pyridazine ligands, show narrow electrochemical band gaps in the range of 1.36-1.84 eV. Solar cells with each dye have been prepared, using both iodide/triiodide and cobalt redox couples as the electrolytes, platinum or carbon as the counter electrodes, and TiO2 or SnO2 as the metal oxide photoelectrodes, respectively. The best DSSC results have been obtained using dye 3, with an overall solar-to-electric conversion efficiency of 3.5%, which greatly overcomes the previous result of 1.0% obtained for dye 1 in a not-optimized setup of the device. The performances of dye 3 are due to the presence of D35 ligand, which further suppresses the recombination of the injected electron with the electrolyte and with the oxidized state of the dye.

Study of Surface Plasmon Assisted Reactions to Understand the Light‐Induced Decarboxylation of N719 Sensitizer

The factors that cause the instability of dye‐sensitized solar cells (DSSCs) remain to be elucidated. In this work, we focus on the light‐induced instability of N719 sensitizer that represents a large class of the ruthenium bipyridine sensitizers in DSSCs through in situ surface‐enhanced Raman spectroscopy (SERS) investigations. Systematic studies of surface plasmon‐driven reactions coupled with density functional theory (DFT) calculations clearly suggest the decarboxylation reaction induced by “hot electrons” generated on plasmonic metal surface as the reason for the instability. This decarboxylation reaction is also validated on TiO2 surface with the assistance of matrix‐assisted laser desorption/ionization time of flight mass spectrometry (MALDI‐TOF‐MS). This reaction is possibly the main reason leading to the inefficiency of N719 sensitization in DSSCs. Our findings may broaden the research scope of surface plasmon‐assisted catalytic reactions and provide insight into the optimal design of ruthenium based photosensitizers for DSSCs.

Exploring the potential of iron to replace ruthenium in photosensitizers: a computational study.

In an effort to replace the widely used ruthenium metal complexes with low-cost, earth abundant iron complexes as photosensitizers for dye-sensitized solar cell (DSSC) applications, herein we report the computational design of heteroleptic iron complexes (FC1-3) coordinated with benzimidazole-phenylcarbene (C^N) ligands. DFT and TDDFT calculations predicted the stronger σ-donating and π-accepting nature of phenyl carbene ligands substituted with electron-withdrawing CF3, donating -N(CH3)2, and benzothiazine annulation than the imidazole carbene ligands (FC4); consequently, the metal-ligand bond distances and interactions that influence the ordering of charge transfer states with respect to metal centered states are altered in FC1-3 complexes. Detailed analysis based on energy decomposition analysis, spin density distribution analysis, and ab initio ligand field theory parameters were enabled to understand the nature of heteroleptic ligand interactions with the rest of the metal complex. The results from the study shed light on the judicious choice of ligands, as the same non-innocent ligand that is experimentally proven as favorable for Ru-dyes (TC1) is found to be detrimental for Fe-dyes (FC1). Among the complexes studied, the FC3 complex is a promising sensitizer for DSSC with 1,3MLCT energy level well separated from 3,5MC, thereby preventing the deactivation of MLCT. The outcome of the study is therefore an important step toward the development of photosensitizers based on iron metal. Graphical abstract Potential photosensitzers based on earth-abundant, low cost iron metal have been designed for dye sensitized solar cell applications.

Synthesis and DSSC Applications of Ru(II) Complexes Bearing Benzimidazole Type Ligands

In this study, the synthesis of 7 Ru(II) polypyridine complexes (C1–7) and their characterization by FT-IR, UV–Vis, 1H-NMR and ESI–MS spectroscopic methods have been reported. The use of the complexes as photosensitizers in dye-sensitized solar cells (DSSCs) has been investigated. The photovoltaic characteristics of the fabricated DSSC devices were examined under 1.5 G solar simulation and TiO2 was used as a semiconductor. Absorption and emission spectra of the complexes were examined, cyclic voltammograms of the Ru complexes were performed and HOMO–LUMO energy levels were calculated. Thus, electrochemical properties of the complexes and the energy diagrams, which shows the charge transfer characteristics of the complexes were studied. The alterations in the current–potential characteristics of the Ru sensitizers by modifications in ligands have been investigated. The effects of the substitutions on ligands are evaluated and power conversion efficiency value up to half of the reference sensitizer was obtained by C6 complex.

Carotenoid pigment as sensitizers for applications of dye-sensitized solar cell (DSSC)

A dye-sensitized solar cell is the third generation of solar cells that can convert solar energy into electrical energy using photo-electrochemical principles. Natural dye extracted from carotenoid pigments such as orange fruits, carrots, and tomatoes. The absorbance of dye and TiO2 were characterized using UV-Vis spectrophotometer. The chemical bond contained TiO2/dye were characterized using FTIR spectrophotometer. The efficiency of DSSC was calculated using I-V meter Keithley. The absorbance spectra results show that carotenoid dyes have peaked in the wavelength range of 400 nm-510 nm. The highest efficiency was obtained from tomatoes dye at 0.03% due to the interaction between TiO2 and carboxyl –OH group. Adsorption of carotenoid dyes on the surface of TiO2 can be used as the photosensitizer for DSSC.

Research Progress on Photosensitizers for DSSC.

Dye sensitized solar cells (DSSC) are considered one of the most promising photovoltaic technologies as an alternative to traditional silicon-based solar cells, for their compatibility with low-cost production methods, their peculiar optical and mechanical properties and the high indoor efficiency. Photosensitizers represent one of the most important components of a DSSC device and probably the most thoroughly investigated in the last twenty years, with thousands of dyes that have been proposed and tested for this kind of application. In this review we aimed to provide an overview of the three main classes of DSSC photosensitizers, namely ruthenium(II) polypyridyl complexes, Zn-porphyrin derivatives and metal-free organic dyes. After a brief introduction about the architecture and operational principles of a DSSC and the state of the art of the other main components of this type of device, we focused our discussion on photosensitizers. We have defined the numerous requirements DSSC photosensitizers should satisfy and have provided an overview of their historical development over the years; by examining specific dyes reported in the literature, we attempted to highlight the molecular design strategies that have been established for the optimization of their performance in real devices both in terms of efficiency (which recently reaches an outstanding 14.3%) and operational stability. Finally, we discussed, in the last section, the possible future developments of this intriguing technology.

Investigation of nanostructured TiO2 thin film coatings for DSSCs application using natural dye extracted from jabuticaba fruit as photosensitizers

Solar power is a renewable and promising solution to the today’s world energy needs. Recently, researchers in finding an alternative energy resource for the next generation lead to the production of efficient photovoltaic cells. Herein, dye-sensitized solar cells (DSSCs) containing semiconducting nanostructured TiO2 thin film photoanodes were fabricated by spin-coating technique, using a self-constructed spin coater, which is a simple and cost-effective method. The composition and superficial characteristics of the films were studied by scanning electron microscopy (SEM), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). Microscopic analysis revealed the electrode surface morphology, and microstructure were influenced by spin-coating technique compared to doctor blade method. The natural dyes of anthocyanin were extracted from jabuticaba (Plinia cauliflora) fruit using a simple extraction technique, used as photosensitizers in DSSCs and their characteristics were studied. The extracts showed the UV–Vis absorptions in the 450–600 nm range with broad maxima at ~ 545 nm. FTIR showed the presence of anthocyanin in the dye molecules of jabuticaba fruit, which can be related to a better photon to electron conversion. The photoelectrochemical performance and the efficiency of assembled DSSCs using jabuticaba fruit dye extract were evaluated, and efficiency enhancement was obtained by spin-coated TiO2 electrodes. The efficiency and fill factor of the DSSC using jabuticaba fruit dye were 0.13% and 0.29%, respectively. The results successfully showed that the DSSC, using jabuticaba fruit extract as a dye photosensitizer, is valuable for the preparation of eco-friendly, less-expensive, renewable, and clean sources of energy.

Functionalized Quinazolines and Pyrimidines for Optoelectronic Materials

Background: Quinazolines, the important group of benzodiazines, are widely known in medicinal chemistry due to their broad spectrum of biological activities. Notably, extensive research on the synthesis and application of quinazoline derivatives for electronic devices, luminescent elements, photoelectric conversion elements, and image sensors has been published recently. Objective: This review reports luminescent small molecules and chelate compounds including a quinazoline or pyrimidine ring in their scaffold highlighting their applications related to photo- and electroluminescence. Conclusion: It is clear from the review of the topic that the incorporation of quinazoline and pyrimidine fragments into π-extended conjugated systems is of great value for the creation of novel optoelectronic materials. Polyhalogen derivatives represent the major starting materials for polysubstituted fluorescent quinazolines. Electroluminescent properties of aryl(hetaryl)substituted quinazolines with π-extended conjugated systems proved to be the most important. Incorporation of benzimidazole, carbazole, triphenylene or triphenylamine fragments into quinazoline scaffold allows fabricating materials for organic light-emitting diodes, including white OLEDs and highly efficient red phosphorescent organic light-emitting diodes. Moreover, arylvinylsubstituted quinazolines are of great interest as potential structures for nonlinear optical materials and for colorimetric pH sensors. Iridium complexes based on 2-aryl(thienyl) quinazoline or pyrimidine derivatives represent high-efficiency phosphorescent materials for OLEDs. Pyrimidine push-pull systems are of considerable importance as potential photosensitizers for dye-sensitized solar cells. Pyrimidine derivatives bearing phenylacridine or phenylphenoxazine fragments at the positions 4 and 6 are capable to function as thermally activated delayed fluorescence emitters.

Retraction Notice: K.U. Isah et al., Betalain Pigments as Natural Photosensitizers for Dye-Sensitized Solar Cells: The Effect of Dye pH on the Photoelectric Parameters, International Letters of Chemistry, Physics and Astronomy, Vol. 55, pp. 86-93, 2015

The article is retracted at the request of a Publisher’s representative and the authors. The Retraction Policy is clearly stated in the journal’s Policy and Ethics statement. During the retraction procedure, the Editors of the journal adhered to the COPE’s Retraction Guidelines. The authors of the retracted paper were informed about retraction in due course.

Retraction Notice: K.U. Isah et al., Betalain Pigments as Natural Photosensitizers for Dye-Sensitized Solar Cells: The Effect of Dye pH on the Photoelectric Parameters, International Letters of Chemistry, Physics and Astronomy, Vol. 55, pp. 86-93, 2015

The article is retracted at the request of a Publisher’s representative and authors. The Retraction Policy is clearly stated in the journal’s Policy and Ethics statement. During the retraction procedure, the Editors of the journal adhered to the COPE’s Retraction Guidelines. The authors of the retracted paper were informed about retraction in due course.

Poly(phenylene cyanovinylenes) carbazole based conjugated polymer as a photosensitizer for dye-sensitized solar cells

A carbazole based new n-type conjugated polymer (CP) has been synthesized and employed as a photosensitizer in polymer-sensitized solar cells (PSSCs). The synthesis of CP was accomplished by the reaction of appropriate monomer dialdehyde with aromatic dinitriles, under Knoevenagel condensation conditions followed by its characterization by 1H NMR and FT-IR. The band gap of CP measured by cyclic voltammetry (CV), density functional theory (DFT) and diffuse reflectance (DR) UV-vis spectroscopy revealed closely matched values of 2.57, 2.47, and 2.64 eV respectively. Under the illumination of AM1.5G (100 mW cm−2), CP based PSSCs exhibited power conversion efficiency of 2.08% with a short-circuit current density (JSC) of 7.0 mA/cm2, an open-circuit voltage (Voc) of 534 mV and a fill factor (FF) of 55.85%.

Dye-sensitized solar cells based on (D−π−A)3L2 phenothiazine dyes containing auxiliary donors and flexible linkers with different length of carbon chain

Four (D−π−A)3L2 phenothiazine dyes (PTZTB1−4) and a reported reference dye (R−SB) with a mono D−π−A chain were utilized as photosensitizers for dye-sensitized solar cells. In the skeleton of the dyes PTZTB1−4, three D−π−A chains (D−π−A)3 were connected by flexible linker of n-hexyl or n-dodecyl group (L2) to build the (D−π−A)3L2 configuration. The effect of both the auxiliary donors and linkers with different length of carbon chains upon the photophysical, electrochemical as well as photovoltaic properties of the (D−π−A)3L2 dyes were further investigated. Results reveal that the dyes PTZTB3−4 containing the auxiliary donor of 4-octyloxyphenyl group show a higher molar extinction coefficient, a broader IPCE response region, and a higher HOMO value than those of PTZTB1−2 and R−SB. Among all of the devices, the cells based on PTZTB2 and PTZTB4 exhibit a higher open circuit voltage due to that the charge recombination is blocked significantly by the n-dodecyl linkers. Meanwhile, a maximal power conversion efficiency of 6.66% is achieved by the device fabricated with PTZTB3. Besides, it is noteworthy that the (D−π−A)3L2 dyes possess a superior adsorbed stability on TiO2 interface than that of the reference dye as a result of the three anchors in a molecule of the former.

Insight into the optoelectronic properties of designed solar cells efficient tetrahydroquinoline dye-sensitizers on TiO2(101) surface: first principles approach

Seven ‘lead’ dye-sensitizers from Tetrahydroquinoline (THQ) family were proposed and designed based on the structural attributes via quantitative-structure property relationship (QSPR) modeling. They were screened rationally through different computational approaches to explore their potential applications as photosensitizers for dye-sensitized solar cells (DSSCs). Compelling photophysical properties such as electron injection driving force, electron injection time, and dye regeneration were studied for the isolated dyes under the DFT and TD-DFT frameworks. Index of spatial extent (S, D, and ∆q), the strength of charge transfer and separation along with the charge transfer process is explored. First principle approach including van der Waals density functional calculation of dye@TiO2 interface indicates that all of the designed dyes have optimal interfacial behavior. Bader charge analysis, partial density of state (PDOS), charge density and electrostatic potential difference calculation confirms that THQ7 and THQ9 are the most efficient dye-sensitizers. The other five designed dyes also possess the required properties to emerge as effective dye-sensitizers potentially better than those already utilized.

PTA-based ruthenium complexes as photosensitizers for dye-sensitized solar cells

Two novel ruthenium complexes are synthesized, photo-characterized and tested as photosensitizers in dye-sensitized solar cells (DSCs): [RuCl2(mPTA)3(H2O)](CF3SO3)3 (C1) (m: methyl; PTA: 3,5,7-triaza-phosphaadamantane) and [Ru(C = C=CPh2)Cp(PTA)(PPh3)](CF3SO3) (C2). The complexes are soluble in organic solvents and, interestingly, in water, which makes them useful for water-based photochemical processes. They possess excellent photon-absorption over a wide range of the spectrum with intense peaks at ∼ 330 nm for both sensitizers. A second peak is found for C2 at 525 nm, wider than the corresponding to the N719 standard dye. DSCs using these sensitizers are evaluated against different electrolytes. The solar cell performance was similar for both complexes and strongly dependent on the electrolyte nature, with a maximum conversion efficiency of 0.32% for the iodide/triiodide electrolyte.

Performance analysis of $$\hbox {TiO}_{2}$$ TiO 2 -flavylium compound-based dye-sensitized solar cell (DSSC): a DFT–TDDFT approach

The computational study of flavylium compound consists of anthocyanin pigments: callistephin, Chrysanthemin, oenin and mytrillin, and anthocyanidin pigments: peonidin and petunidin dyes are used to identify the potential photosensitizer for dye-sensitized solar cell (DSSC). Density functional theory is adopted to study methoxyl and hydroxyl groups in six pigments. The computed results of six dyes show good oscillator strength (f), light harvesting efficiency, electron injection $$(\Delta G^\mathrm{{inject}})$$ and electron regeneration $$({\Delta } G^\mathrm{{regen}})$$ . The short-circuit current density $$({J}_{\mathrm{sc}})$$ , total reorganization energy $$({\uplambda }_{\mathrm{total}})$$ and open-circuit voltage $$({V}_{\mathrm{oc}})$$ were also discussed. Intermolecular charge transfer of six dyes was examined using frontier molecular orbital. However, Peonidin/Titanium dioxide system has shown a significant response in density of states. Hence, this study confirms peonidin dye can be used as a photosensitizer for DSSC applications.

Metallophthalocyanines bearing four 3-(pyrrol-1-yl)phenoxy units as photosensitizer for dye-sensitized solar cells

In this article, the synthesis of non-peripheral metallophthalocyanines (cobalt, zinc, and manganese) bearing four 3-(pyrrol-1-yl)phenoxy units was reported. The new compounds have been characterized using UV-Vis, FT-IR, 1H NMR, and mass spectroscopic data. Aggregation behaviors of phthalocyanines were investigated in concentrations ranging from 14 × 10−6 to 2 × 10−6 M. Electrochemical measurements gave well illustrated redox activities of MnClPc and CoPc. Electrochemical and spectroelectrochemical studies showed that MnClPc gives two metal-based reduction processes in addition to the one ring-based reduction and one ring-based oxidation process. Distinct color differences between the electrogenerated MnClPc species were observed during in situ spectroelectrochemical measurements. The potential of these compounds as photosensitizers and dependence of the photovoltaic performance on the thickness of photoanode layer were investigated. For this purpose, DSSC devices were fabricated with the structure of FTO/TiO2:4–6/Electrolyte/Pt/FTO and characterized under AM 1.5 illuminations. By using 6 as dye a photovoltaic conversion efficiency of 2.44% with short circuit current density of 7.17 mA cm−2 and open circuit voltage of 0.68 V was observed.

A natural tomato slurry as a photosensitizer for dye-sensitized solar cells with TiO2/CuO composite thin films

ABSTRACTWe have studied the performance of dye-sensitized solar cells by employing natural dye “anthocyanins” extracted from the tomato slurry as a sensitizer for the TiO2/CuO photoanode. The extracts were anchored on TiO2/CuO films deposited on an ITO substrate which was used as a photoanode. The dye adsorbed TiO2/CuO films electrode, the copper plate as a counter electrode, and iodolyte as an electrolyte were assembled into DSSCs. The conversion efficiency of the DSSCs was found to be 2.96% with a VOC of 0.615 V, JSC of 6.6 mA/cm2, and an FF of 0.73. This work highlights the use of contribution of the tomato slurry as a natural sensitizer to enhance the efficiency of DSSCs.

Binaphthyl-containing Schiff base complexes with carboxyl groups for dye sensitized solar cell: An experimental and theoretical study

We report on synthesis and characterization of binaphthyl containing Schiff base Ni(II), Cu(II), and Zn(II) complexes as promising photosensitizers for dye-sensitized solar cells (DSSC). Based on theoretical and experimental data, the possibility of their application in DSSC was confirmed. To our knowledge, we find dye performance of complex is steric and rigid structure widely spread to efficiency. The spatial and electronic structures of the complexes were studied by means of the quantum chemical modeling using DFT and TD-DFT approaches. The adsorption energies of the complexes on TiO2 cluster were calculated and appeared to be very close in value. The Zn(II) complex has the biggest value of molar extinction.