Exploring the Role of Central Metals in Bulky Phthalocyanines for Dye-Sensitized Solar Cells.

Two series of metallo-(Zn(II), Mg(II), and Ru(II)) and free-base phthalocyanines (Pcs) with a carboxyl anchoring group and well-established bulky peripheral substituents (either tert-butyl or bulky 2,6-diisopropylphenoxy) were synthesized and tested as sensitizers in dye-sensitized solar cells (DSSCs). The trend of photovoltaic efficiencies (PCEs) for free-base and metallo Pcs followed the order Zn(II)Pc>Mg(II)Pc≫H2Pc ≈ Ru(II)Pc regardless of the peripheral substitution. Higher efficiencies (4.95 versus 3.63 for the Zn(II) derivatives) were achieved with Pcs bearing the bulkier 2,6-diisopropylphenoxy group, indicating a lower aggregation and more suitable HOMO-LUMO levels. Furthermore, these derivatives showed a morelevant influence of the metal on the PCE values (from the highest 4.95 for the Zn(II)Pc to the lowest 0.23 for the Ru(II)Pc. In both series, the best PCEs observed with the Zn(II) derivatives were mainly due to their highest Jsc values. The lowest efficiencies found for the free-bases and Ru(II) derivatives were attributed to a mismatch between their LUMO levels and the conduction band of the TiO2,and lower light-harvesting capabilities, respectively. In conclusion, Zn(II) derivatives are still the best Pc candidates to use as sensitizers in molecular photovoltaics.

Development of dye-sensitized solar cells using pigment extracts produced by Talaromyces atroroseus GH2.

The identification of more efficient, clean, secure, and competitive energy supply is necessary to align with the needs of sustainable devices. For this reason, a study for developing innovative dye-sensitized solar cells (DSSCs) based on microbial pigments is reported starting from Talaromyces atroroseus GH2. The fungus was cultivated by fermentation and the extracellular pigment extract was characterized by HPLC-DAD-ESI-MS analyses. The most abundant compound among the 22 azaphilone-type pigments identified was represented by PP-O. The device's behavior was investigated in relation to electrolyte and pH for verifying the stability on time and the photovoltaic performance. Devices obtained were characterized by UV-vis measurements to verify the absorbance intensity and transmittance percentage. Moreover, photovoltaic parameters through photo-electrochemical measurements (I-V curves) and impedance characteristics by Electrochemical Impedance Spectroscopy (EIS) were determined. The best microbial device showed a short-circuit current density (Jsc) of 0.69 mA/cm2, an open-circuit photo-voltage (Voc) of 0.27 V and a Fill Factor (FF) of 0.60. Furthermore, the power conversion efficiency (PCE) of the device was 0.11%. Thus, the present study demonstrated the potential of microbial origin pigments for developing DSSCs.

Dye-sensitized solar cells based on anatase- and brookite-TiO2: enhancing performance through optimization of phase composition, morphology and device architecture.

Herein, we demonstrate an optimization of dye-sensitized solar cells (DSSCs) through the development of single-layer and double-layer configurations. Focusing on the incorporation of brookite and anatase phases in varying ratios, the study aims to determine the optimal composition for enhanced photovoltaic performance. The active layer, composed of anatase- and brookite-TiO2nanoparticles, is further modified with a scattering layer comprising a mixture of anatase nanoparticles and brookite-TiO2in the form of nanocube or rice-like particles. The synthesis of TiO2nanostructures with various morphologies and phase compositions and their subsequent application in single-layer and double-layer DSSCs are presented. The results highlight the superior light-harvesting capabilities achieved through the strategic incorporation of brookite phase into the anatase phase, emphasizing the importance of optimizing the anatase: brookite ratio. The single-layer DSSCs exhibit a peak efficiency of 8.73%, achieved with a composition of 30 wt.% brookite and 70 wt.% anatase at a thickness of 15µms. In the context of double-layer DSSCs, the combined optimization of the active layer composition, scattering layer morphology, and utilization of anatase nanoparticles leads to a remarkable efficiency of 9.18%. These findings underscore the critical role of composition and morphology in enhancing the performance of DSSCs, showcasing the potential for brookite-based DSSCs in solar energy conversion.

Synthesis and Photovoltaic Performance of ß-Amino-Substituted Porphyrin Derivatives.

New ß-amino-substituted porphyrin derivatives bearing carboxy groups were synthesized and their performance as sensitizers in dye-sensitized solar cells (DSSC) was evaluated. The new compounds were obtained in good yields (63-74%) through nucleophilic aromatic substitution reactions with 3-sulfanyl- and 4-sulfanylbenzoic acids. Although the electrochemical studies indicated suitable HOMO and LUMO energy levels for use in DSSC, the devices fabricated with these compounds revealed a low power conversion efficiency (PCE) that is primarily due to the low open-circuit voltage (Voc) and short-circuit current density (Jsc) values.

Voltage- and Power-Conversion Performance of Bi-functional ZrO2 : Er3+ / Yb3+ Assisted and Co-sensitized Dye Sensitized Solar Cells for Internet of Things Applications.

Giant power conversion efficiency is achieved by using bifunction ZrO2 : Er3+ /Yb3+ assisted co-sensitised dye-sensitized solar cells. The evolution of the crystalline structure and its microstructure are examined by X-ray diffraction, scanning electron microscopy studies. The bi-functional behaviour of ZrO2 : Er3+ /Yb3+ as upconversion, light scattering is confirmed by emission and diffused reflectance studies. The bi-function ZrO2 : Er3+ /Yb3+ (pH=3) assisted photoanode is co-sensitized by use of N719 dye, squaraine SPSQ2 dye and is sandwiched with Platinum based counter electrode. The fabricated DSSC exhibited a giant power conversion efficiency of 12.35 % with VOC of 0.71 V, JSC of 27.06 mA/cm2 , FF of 0.63. The results, which motivated the development of a small DSSC module, gave 6.21 % and is used to drive a tiny electronic motor in indoor and outdoor lighting conditions. Small-area DSSCs connected in series have found that a VOC of 4.52 V is sufficient to power up Internet of Things (IoT) devices.

Biosynthesis, characterization and optimization of TiO2 nanoparticles by novel marine halophilic Halomonas sp. RAM2: application of natural dye-sensitized solar cells.

BACKGROUND: Metal oxide nanoparticles (NPs) are becoming valuable due to their novel applications. The green synthesis of TiO2 NPs is more popular as a flexible and eco-friendly method compared to traditional chemical synthesis methods. TiO2 NPs are the most commonly used semiconductor in dye-sensitized solar cells (DSSCs). RESULTS: The biogenic TiO2 NPs were produced extracellularly by the marine halophilic bacterium Halomonas sp. RAM2. Response surface methodology (RSM) was used to optimize the biosynthesis process, resulting in a starting TiO2 concentration of 0.031 M and a pH of 5 for 92 min (⁓15 nm). TiO2 NPs were well-characterized after the calcination process at different temperatures of 500, 600, 700 and 800 °C. Anatase TiO2 NPs (calcined at 500 °C) with a smaller surface area and a wider bandgap were nominated for use in natural dye-sensitized solar cells (NDSSCs). The natural dye used as a photosensitizer is a mixture of three carotenoids extracted from the marine bacterium Kocuria sp. RAM1. NDSSCs were evaluated under standard illumination. After optimization of the counter electrode, NDSSCBio(10) (10 layers) demonstrated the highest photoelectric conversion efficiency (η) of 0.44%, which was almost as good as NDSSCP25 (0.55%). CONCLUSION: The obtained results confirmed the successful green synthesis of TiO2 NPs and suggested a novel use in combination with bacterial carotenoids in DSSC fabrication, which represents an initial step for further efficiency enhancement studies.

A Green Approach to Natural Dyes in Dye-Sensitized Solar Cells.

Solar cells are pivotal in harnessing renewable energy for a greener and more sustainable energy landscape. Nonetheless, eco-friendly materials for solar cells have not been as extensive as conventional counterparts, highlighting a significant area for further investigation in advancing sustainable energy technologies. This study investigated natural dyes from cost-effective and environmentally friendly blueberries and mulberries. These dyes were utilized as alternative sensitizers for dye-sensitized solar cells (DSSCs). Alongside the natural dyes, a green approach was adopted for the DSSC design, encompassing TiO2 photoanodes, eco-friendly electrolytes, and green counter-electrodes created from graphite pencils and candle soot. Consequently, the best-optimized dye sensitizer was mulberry, with an output power of 13.79 µW and 0.122 µW for outdoor and indoor environments, respectively. This study underscored the feasibility of integrating DSSCs with sensitizers derived from readily available food ingredients, potentially expanding their applications in educational kits and technology development initiatives.

Recent Investigations on the Use of Copper Complexes as Molecular Materials for Dye-Sensitized Solar Cells.

Three decades ago, dye-sensitized solar cells (DSSCs) emerged as a route for harnessing the sun's energy and converting it into electricity. Since then, an impressive amount of work has been devoted to improving the global photovoltaic efficiency of DSSCs, trying to optimize all components of the device. Up to now, the best efficiencies have usually been reached with ruthenium(II) photosensitizers, even if in the last few years many classes of organic compounds have shown record efficiencies. However, the future of DSSCs is stringently connected to the research and development of cheaper materials; in particular, the replacement of rare metals with abundant ones is an important topic in view of the long-term sustainability of DSSCs intended to replace the consolidated fossil-based technology. In this context, copper is a valid candidate, being both an alternative to ruthenium in the fabrication of photosensitizers and a material able to replace the common triiodide/iodide redox couple. Thus, recently, some research papers have confirmed the great potential of copper(I) coordination complexes as a cheap and convenient alternative to ruthenium dyes. Similarly, the use of copper compounds as electron transfer mediators for DSSCs can be an excellent way to solve the problems related to the more common I3-/I- redox couple. The goal of this mini-review is to report on the latest research devoted to the use of versatile copper complexes as photosensitizers and electron shuttles in DSSCs. The coverage, from 2022 up to now, illustrates the most recent studies on dye-sensitized solar cells based on copper complexes as molecular materials.

Bifacial Dye-Sensitized Solar Cells Utilizing Visible and NIR Dyes: Implications of Dye Adsorption Behaviour.

Bifacial dye-sensitized solar cells (DSSCs) were fabricated utilizing dye cocktails of two dyes, Z-907 and SQ-140, which have complementary light absorption and photon harvesting in the visible and near-infrared wavelength regions, for panchromatic photon harvesting. The investigation of the rate of dye adsorption and the binding strengths of the dyes on mesoporous TiO2 corroborated the finding that the Z-907 dye showed a rate of dye adsorption that was about >15 times slower and a binding that was about 3 times stronger on mesoporous TiO2 as compared to SQ-140. Utilizing the dye cocktails Z-907 and SQ-140 from ethanol, the formation of the dye bilayer, which was significantly influenced by the ratio of dyes and adsorption time, was demonstrated. It was demonstrated that the dyes of Z-907 and SQ-140 prepared in 1:9 or 9:1 molar ratios favoured the dye bilayer formation by subtly controlling the adsorption time. In contrast, the 1:1 ratio counterpart was prone to form mixed dye adsorption; the best performance of the BF-DSSCs was shown when a dye cocktail of Z-907 and SQ-140 in a molar 9:1 ratio was used to prepare a photoanode for 1 h of dye adsorption. The BF-DSSCs thus exhibited PCEs of 4.23% and 3.48% upon the front and rear side light illuminations, a cumulated PCE of 7.71%, and a very good BBF of 83%.

A Review of Synthesis and Applications of Al2O3 for Organic Dye Degradation/Adsorption.

This comprehensive review investigates the potential of aluminum oxide (Al2O3) as a highly effective adsorbent for organic dye degradation. Al2O3 emerges as a promising solution to address environmental challenges associated with dye discharge due to its solid ceramic composition, robust mechanical properties, expansive surface area, and exceptional resistance to environmental degradation. The paper meticulously examines recent advancements in Al2O3-based materials, emphasizing their efficacy in both organic dye degradation and adsorption. Offering a nuanced understanding of Al2O3's pivotal role in environmental remediation, this review provides a valuable synthesis of the latest research developments in the field of dye degradation. It serves as an insightful resource, emphasizing the significant potential of aluminum oxide in mitigating the pressing environmental concerns linked to organic dye discharge. The application of Al2O3-based catalysts in the photocatalytic treatment of multi-component organic dyes necessitates further exploration, particularly in addressing real-world wastewater complexities.

Designing Efficient Metal-Free Dye-Sensitized Solar Cells: A Detailed Computational Study.

The modulation of molecular characteristics in metal-free organic dyes holds significant importance in dye-sensitized solar cells (DSSCs). The D-π-A molecular design, based on the furan moiety (π) in the conjugated spacer between the arylamine (D) and the 2-cyanoacrylic acid (A), was developed and theoretically evaluated for its potential application in DSSCs. Utilizing linear response time-dependent density functional theory (TDDFT) with the CAM-B3LYP functional, different donor and acceptor groups were characterized in terms of the electronic absorption properties of these dyes. All the studied dye sensitizers demonstrate the ability to inject electrons into the semiconductor's conduction band (TiO2) and undergo regeneration through the redox potential triiodide/iodide (I3-/I-) electrode. TDDFT results indicate that the dyes with CSSH anchoring groups exhibit improved optoelectronic properties compared to other dyes. Further, the photophysical properties of all dyes absorbed on a Ti(OH)4 model were explored and reported. The observed results indicate that bidentate chemisorption occurs between dyes and TiO4H5. Furthermore, the HOMO-LUMO energy gaps for almost all dye complexes are significantly smaller than those of the free dyes. This decrease of the HOMO-LUMO energy gaps in the dye complexes facilitates electron excitation, and thus more photons can be adsorbed, guaranteeing larger values of efficiency and short-circuit current density.

Boosting the Efficiency of Dye-Sensitized Solar Cells by a Multifunctional Composite Photoanode to 14.13 .

We report a new strategy to fabricate a multifunctional composite photoanode containing TiO2 hollow spheres (TiO2 -HSs), Au nanoparticles (AuNPs) and novel NaYF4 : Yb,Er@NaLuF4 : Eu@SiO2 upconversion nanoparticles (UCNPs). The AuNPs are grown on the photoanode film including TiO2 -HSs and UCNPs by a simple in situ plasmonic treatment. As a result, an impressive power conversion efficiency of 14.13 % is obtained, which is a record for N719 dye-based dye-sensitized solar cells, demonstrating great potential for the solar cells toward commercialization. This obvious enhancement is ascribed to a collaborative mechanism of the TiO2 -HSs exhibiting excellent light-scattering ability, of the UCNPs converting near-infrared photons into visible photons and of the AuNPs presenting outstanding surface plasmon resonance effect. Notably, a steady-state experiment further reveals that the champion cell exhibits 95.33 % retainment in efficiency even after 180 h of measurements, showing good device stability.

Adamantyl Side Chains as Anti-Aggregating Moieties in Dyes for Dye-Sensitized Solar Cells.

Designing and evaluating novel dye concepts is crucial for the development of the field of dye-sensitized solar cells (DSSCs). In our recent report, the novel concept of tethering the anti-aggregation additive chenodeoxycholic acid (CDCA) to dyes for DSSC was introduced. Based on the performance improvements seen for this modification, the aim of this study is to see if a simplified anti-aggregation unit could achieve similar results. The following study reports the synthesis and photovoltaic characterization of two novel dyes decorated with the steric ethyladamantyl moiety on the π-spacer, and on the triarylamine donor. This modification is demonstrated to be successful in increasing the photovoltages in devices employing copper-based electrolytes compared to the non-modified reference dye. The best photovoltaic performance is achieved by a device prepared with the adamantyl decorated donor dye and CDCA, this device achieves a power conversion efficiency of 6.1 % (Short-circuit current=8.3 mA cm-2 , Open-circuit voltage=1054 mV, Fill factor=0.69). The improved photovoltaic performance seen for the adamantyl decorated donor demonstrate the potential of ethyladamantyl side chains as a tool to ensure surface protection of TiO2 .

1,2,4-Triazine-based Materials: Spectroscopic Investigation, DFT, NBO, and TD-DFT Calculations as Well As Dye-sensitized Solar Cells Applications.

In this manuscript, we report four series for 1,2,4-triazine derivatives as dye-sensitized solar cells (DSSCs). Density functional theory (DFT) methods via utilizing Becke's three-parameter functional and LeeeYangeParr functional (B3LYP) level with 6-31G (d, p) basis set to investigate their modeling molecular structures. Optimized molecular structures for studied molecular structures are obtained using the DFT/B3LYP/6-31G (d, p) method. In addition, the time-dependant density functional theory (TD-DFT) is used to study the optoelectronic properties and absorption spectra using DFT/CAM-B3LYP/ 6-31G + + (d, p) level in the Gaussian 09 program. The highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO), energy gap (Eg), light harvest efficiency (LHE), and open-circuit voltage (Voc) of the studied molecular structures are calculated and illustrated. These properties indicate that these molecular modeling structures as good candidates for utilization in organic DSSCs.

Photoelectrochemical Polymerization for Solid-State Dye-Sensitized Solar Cells.

Dye-sensitized solar cells represent promising alternative photovoltaic (PV) technologies with the advantages of low material cost, ease of production, and high performance for indoor applications. Solid-state DSCs (ssDSCs) have been developed to greatly diminish the problems of electrolyte leakage and electrode corrosion. However, the power conversion efficiency of ssDSCs generally is much lower than traditional liquid DSCs, resulting in low conductivity and poor pore infiltration of solid HTMs in mesoporous structures. To overcome these problems, in situ photoelectrochemical polymerization (PEP) approach is developed to synthesize polymer HTMs in the porous electrodes, enabling enhancement of pore infiltration fraction and conductivity. The PEP method offers great opportunities for engineering the HTM interfaces, tuning the charge dynamics, and improving the PV performance of ssDSCs. Here the authors aim to present a coherent review of the recent development of material engineering and interfacial optimization for ssDSCs. The recent advances in the PEP are also summarized, with special emphasis on how the influencing factors control the PEP kinetics, the polymer properties as well as the device performance. This review provides a deep understanding of the mechanism of photopolymerization across different conditions, which serves as a guidebook for further optimization of the PEP process for ssDSCs.

Tetramethyl Succinonitrile as a Solid Plasticizer in a Poly(ethylene oxide)8 -LiI-I2 Solid Polymer Electrolyte.

Dye-sensitized solar cell (DSSC) is a promising alternative to the commercially available amorphous silicon-based solar cell because of several advantageous properties. A DSSC with a fast ion conducting solid polymer electrolyte is required for the arid atmosphere of Gulf countries. In this work, a new matrix, poly(ethylene oxide)-tetramethyl succinonitrile blend to synthesize a blend-LiI-I2 solid polymer electrolyte for the DSSC application has been proposed. The tetramethyl succinonitrile is a member of plastic crystal with a solid-solid phase transition temperature (Tpc ) of ≈71 °C and melting temperature (Tm ) of ≈170.5 °C. Its molar fraction, 0.1-0.15 is sufficient enough for synthesizing a polymer electrolyte with electrical conductivity of >10-4 S cm-1 at room temperature. This electrolyte shows Vogel-Tamman-Fulcher type behavior with a low value (≈0.083 eV) of pseudo-activation energy for easy ion transport. The results of Fourier-transform infrared spectroscopy, X-ray diffractometry, and differential scanning calorimetry studies reveal the plasticizing effect of tetramethyl succinonitrile to form an amorphous phase. This electrolyte results in a ≈661% gain in short-circuit current density and thereby a ≈552% gain in the cell efficiency (≈3.5%) with respect to the DSSC prepared with the tetramethyl succinonitrile-free electrolyte.

UV-Vis Spectroscopy, Electrochemical and DFT Study of Tris(ß-diketonato)iron(III) Complexes with Application in DSSC: Role of Aromatic Thienyl Groups.

A series of tris(ß-diketonato)iron(III) complexes, with the ß-diketonato ligand bearing different substituent groups, have been synthesized and characterized by Fourier transform infrared (FT-IR), ultraviolet-visible (UV-Vis) and mass spectroscopic methods. The maximum band UV-Vis absorption wavelengths of the tris(ß-diketonato)iron(III) complexes were in the range of 270-380 nm. The complexes have very good solubility in various solvents such as chloroform, dichloromethane, ethyl acetate, tetrahydrofurane, dimethylsulphoxide and dimethylformamide. After the syntheses and characterization processes, spectroscopic and electrochemical properties of these tris(ß-diketonato)iron(III) complexes were investigated. A density functional theory (DFT) study related to the spectroscopic and electrochemical properties of the tris(ß-diketonato)iron(III) complexes was used to investigate the possible application of these complexes as dye sensitizers or redox mediators in dye-sensitized solar cells.

Deep Eutectic Solvents in Solar Energy Technologies.

Deep Eutectic Solvents (DESs) have been widely used in many fields to exploit their ecofriendly characteristics, from green synthetic procedures to environmentally benign industrial methods. In contrast, their application in emerging solar technologies, where the abundant and clean solar energy is used to properly respond to most important societal needs, is still relatively scarce. This represents a strong limitation since many solar devices make use of polluting or toxic components, thus seriously hampering their eco-friendly nature. Herein, we review the literature, mainly published in the last few years, on the use of DESs in representative solar technologies, from solar plants to last generation photovoltaics, featuring not only their passive role as green solvents, but also their active behavior arising from their peculiar chemical nature. This collection highlights the increasing and valuable role played by DESs in solar technologies, in the fulfillment of green chemistry requirements and for performance enhancement, in particular in terms of long-term temporal stability.

Organic Electronics from Nature: Computational Investigation of the Electronic and Optical Properties of the Isomers of Bixin and Norbixin Present in the Achiote Seeds.

Organic compounds have been employed in developing new green energy solutions with good cost-efficiency compromise, such as photovoltaics. The light-harvesting process in these applications is a crucial feature that still needs improvements. Here, we studied natural dyes to propose an alternative for enhancing the light-harvesting capability of photovoltaics. We performed density functional theory calculations to investigate the electronic and optical properties of the four natural dyes found in achiote seeds (Bixa orellana L.). Different DFT functionals, and basis sets, were used to calculate the electronic and optical properties of the bixin, norbixin, and their trans-isomers (molecules present in Bixa orellana L.). We observed that the planarity of the molecules and their similar extension for the conjugation pathways provide substantially delocalized wavefunctions of the frontier orbitals and similar values for their energies. Our findings also revealed a strong absorption peak in the blue region and an absorption band over the visible spectrum. These results indicate that Bixa orellana L. molecules can be good candidates for improving light-harvesting in photovoltaics.

Triazine: An Important Building Block of Organic Materials for Solar Cell Application.

Since the beginning of the 21st century, triazine-based molecules have been employed to construct different organic materials due to their unique optoelectronic properties. Among their applications, photovoltaics stands out because of the current need to develop efficient, economic, and green alternatives to energy generation based mainly on fossil fuels. Here, we review all the development of triazine-based organic materials for solar cell applications, including organic solar cells, dye-sensitized solar cells, and perovskite solar cells. Firstly, we attempt to illustrate the main synthetic routes to prepare triazine derivatives. Then, we introduce the main aspects associated with solar cells and their performance. Afterward, we discuss different works focused on the preparation, characterization, and evaluation of triazine derivatives in solar cells, distinguishing the type of photovoltaics and the role of the triazine-based material in their performance (e.g., as a donor, acceptor, hole-transporting material, electron-transporting material, among others). Throughout this review, the progress, drawbacks, and main issues of the performance of the mentioned solar cells are exposed and discussed. Finally, some conclusions and perspectives about this research topic are mentioned.