Dyes For Dye-sensitized Solar Cells Research Articles

Investigation of the impact of internal acceptor and π-linker in 2, 5-di(2-thienyl)pyrrole based organic dye photosensitizer for DSSCs

The effect of π-linkers and internal acceptor group on the optoelectronic characteristics of D-π-A and D-A′-π-A dyes for dye-sensitized solar cells (DSSC) were examined. The DFT was used for estimating geometries and charge transport parameters, and the TD-DFT for calculating electronic excitations of these dyes. HOMO, LUMO, and HOMO-LUMO energy gap were also calculated for appreciating the suitable electron transfer, dye regeneration, and charge injection. For achieving the improved performance of dyes in DSSC, injection driving force (ΔGinj), short circuit current (JSC), the open circuit voltage (VOC), light harvesting efficiency (LHE), dye regeneration energy (ΔGreg), and Power conversion efficiency were also determined. For suitable Power conversion efficiency of the DSSCs, electron affinity (EA), hole and electron extraction potential, Ionization potential (IP), Total density of states, and Electrostatic potential (ESP) were also calculated. The result shows that the internal acceptor and π-linkers affect the photovoltaic parameters and a small variations in the dye architecture increase the efficiency of DSSCs. The dyes containing diphenyl π-linkers showed maximum power conversion efficiency for solar cell.

Novel unsymmetrical squaraine dyes for dye-sensitized solar cells: Synthesis, characterization, and comparative photovoltaic performance of USQI-NPh2Me2 and USQI-OMe

This study presents the synthesis, characterization, and photovoltaic performance of two novel unsymmetrical squaraine dyes, USQI-NPh2Me2 and USQI-OMe, engineered for application in dye-sensitized solar cells (DSSCs). These chromophores were functionalized with distinct electron-donating groups, di-p-tolylamine for USQI-NPh2Me2 and methoxy for USQI-OMe. Their molecular structures were confirmed through FT-IR, 1HNMR, 13C NMR, and mass spectrometry. Comprehensive photophysical and electrochemical studies were conducted to fine-tune the HOMO and LUMO energy levels of both dyes, optimizing charge injection into the TiO2 conduction band and facilitating dye regeneration with the iodolyte (I₃⁻/I⁻) redox mediator. USQI-NPh2Me2 exhibited a strong absorption maximum at 661 nm, achieving a high short-circuit current density (JSC) of 13.17 mA/cm2, an open-circuit voltage (VOC) of 0.71V, and an overall efficiency of 7.01 %. USQI-OMe, with its absorption peak at 651 nm, reached a JSC of 11.88 mA/cm2, a higher VOC of 0.72 V, but a slightly lower overall efficiency of 6.41 %. Both dyes demonstrated reduced aggregation on the TiO2 surface, contributing to enhanced DSSCs performance. A Comparative analysis revealed that USQI-NPh2Me2 exhibits higher efficiency, while USQI-OMe provided a greater voltage output, highlighting the influence of electron-donating groups on photovoltaic properties. These findings provide valuable insights into structure-property relationships in unsymmetrical squaraine dyes, paving the way for future DSSCs chromophore design and optimization.

Advanced High-Throughput Rational Design of Porphyrin-Sensitized Solar Cells Using Interpretable Machine Learning.

Accurately predicting the power conversion efficiency (PCE) in dye-sensitized solar cells (DSSCs) represents a crucial challenge, one that is pivotal for the high throughput rational design and screening of promising dye sensitizers. This study presents precise, predictive, and interpretable machine learning (ML) models specifically designed for Zn-porphyrin-sensitized solar cells. The model leverages theoretically computable, effective, and reusable molecular descriptors (MDs) to address this challenge. The models achieve excellent performance on a "blind test" of 17 newly designed cells, with a mean absolute error (MAE) of 1.02%. Notably, 10 dyes are predicted within a 1% error margin. These results validate the ML models and their importance in exploring uncharted chemical spaces of Zn-porphyrins. SHAP analysis identifies crucial MDs that align well with experimental observations, providing valuable chemical guidelines for the rational design of dyes in DSSCs. These predictive ML models enable efficient in silico screening, significantly reducing analysis time for photovoltaic cells. Promising Zn-porphyrin-based dyes with exceptional PCE are identified, facilitating high-throughput virtual screening. The prediction tool is publicly accessible at https://ai-meta.chem.ncu.edu.tw/dsc-meta.

Investigation of heterocyclic azo dyes for dye-sensitized solar cells and non-linear optical properties: Synthesis and in-silico studies

Four thiophene-based donor-π-azo-acceptor dyes were designed and synthesized with benzoic and salicylic acids anchoring groups for dye-sensitized solar cells (DSSC). The results show that the orientation of the secondary donor significantly affects molecular planarity, which in turn affects the characteristics of charge transfer (CT) inside the backbones of thiophene-azo-benzoic or salicylic acids. These results have been confirmed by the time-dependent density functional theory (TD-DFT) study, which shows that the dyes' vertical absorption maximum increases as the secondary donors' providing strength increases. Photovoltaic parameters indicate an increase in DSSC performance from PG9 to PG12. Moreover, dye@TiO2 cluster investigations suggest that these dyes could combine with TiO2 to cause dye@TiO2 cluster absorbance to shift red.The synthesis of PG9 to PG12 confirms theoretical predictions, with initial absorption in dimethylformamide (DMF) and energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) following a pattern like that seen in density functional theory (DFT) investigations. According to TGA data, PG9 to PG12 have exceptional thermal stability, making them suitable for DSSCs. The built-in DSSCs had varying efficiencies; PG10 had the highest efficiency at 4.73 ± 0.1, and PG12 had the lowest at 1.72 ± 0.1. According to the theoretical and practical DSSC results, secondary donors are essential in defining molecular properties and device performance.

Enhanced Efficiency of Dye-Sensitized Solar Cells by Controlled Co-Adsorption Self-Assembly of Dyes.

Single dyes typically exhibit limited light absorption in dye-sensitized solar cells (DSSCs). Thus, cosensitization using two or more dyes to enhance light-harvesting efficiency has been explored; however, the aggregation of dyes can adversely affect electron injection capabilities. This study focused on the design and synthesis of three dyes with a common carbazole donor for DSSCs: DZ102, TZ101, and JM102. JM102 broadens the absorption spectrum by replacing the benzoic acid electron acceptor of TZ101 with acetylenic benzoic acid. A cosensitized DSSC device based on CO-1 [DZ102:TZ101 = 1:1 (50 μM:50 μM)] achieved a short-circuit current density of 19.4 mA/cm2 and a power conversion efficiency of 10.9%. For the first time, the molecular interactions between the dyes in the photoanode were demonstrated using cyclic voltammetry, which revealed the presence of intermolecular forces. Adsorption kinetics further indicated that these forces promoted the self-assembly of dyes during adsorption, which resulted in a cosensitization adsorption amount greater than the sum of the individual dye adsorptions. This study provides novel insights into the selection of cosensitizing dyes for DSSCs.

Triazatruxene Amine Donor-Based Visible-Light-Responsive Unsymmetrical Squaraine Dyes for Dye-Sensitized Solar Cells

Triazatruxene Amine Donor-Based Visible-Light-Responsive Unsymmetrical Squaraine Dyes for Dye-Sensitized Solar Cells

Combine Improvement for Dye-Sensitized Solar Cells

Dye Sensitized-Solar Cells (DSSC) represent a third-generation solar cell technology based on photoelectrochemical principles. This study explores the use of Clitoria ternatea (butterfly pea) extract as an organic dye for DSSCs, focusing on its ability to absorb sunlight effectively. Excitation of electrons triggered by light in photocatalysis is strongly influenced by the position of the band gap. To be effective as a photocatalyst, the material must have a conduction band with a high positive potential compared to the electron accepting potential. Doping metal oxides such as CuO, MgO, Fe2O3, and ZnO into TiO2 can change the band edge properties or surface states which can increase light absorption. This research presents the synthesis of TiO2 nanoparticles as photoanodes doped using metal oxides to evaluate characteristic that can influence DSSC performance. TiO2 nanoparticles doped with metal oxide were synthesized using the solvothermal method and characterized by XRD, SEM-EDX, FTIR, and UV-Vis. Comprehensive analysis of samples doped with metal oxides significantly affects the crystal structure, morphology, elemental composition, and optical properties of the material. The results showed that Cu-doped TiO2 samples allowed for the most significant performance improvement in DSSC, followed by Fe-doped TiO2, Mg-doped TiO2, and Zn-doped TiO2, with pure TiO2 having the lowest performance potential. These results provide important insights into material optimization to improve DSSC efficiency.

Natural dyes (Tithonia diversifolia, Tagetes minuta and Bidens pilosa) sensitized solar cells with reduced graphene based electrodes

The search for suitable alternatives to non-renewable polluting energy sources is a continuous and an active undertaking. There is particular focus towards production of low cost, eco-friendly and more efficient dye sensitized solar cells (DSSCs). Natural dyes DSSCs have the capability of generating green energy at low production cost and hence become a promising class of photovoltaic cells. However, there are inherent problems encountered by the conventional DSSCs including photoanode and cathode related problems such as high cost and electron-hole recombination resulting in a low rate of photoelectric conversion efficiency. In this work, organic dyes from Tithonia diversifolia, Tagetes minuta and Bidens pilosa were used as sensitizers as replacement of synthetic dyes of the conventional DSSCs. The study in addition sought to replace conventional photoanode and cathodes with rGO-TiO2 photo anode and rGO counter electrode. The Tithonia diversifolia has one absorption peak at 665 nm indicating the presence of chlorophyll dye while Tagetes minuta has absorbption peaks at 534 nm suggestive of anthocyanin dye (a flavonoid), 607 nm and 660 nm confirming the presence of chlorophyll a dyes while Bidens pilosa has an absorption peak at 665 nm which again suggests the presence of chlorophyll dye. The tendency of the three natural dyes to absorb in the regions above 650 nm indicates their usefulness for use as dyes for DSSC. The I-V curves of the fabricated natural DSSCs show that when TiO2 is used as the photo anode, Tithonia diversifolia registered a higher efficiency of 0.18 % while Tagetes minuta had the lowest efficiency of 0.08 %. When rGO is incorporated in the TiO2 photo anode, there is an improvement in the solar cell efficiency for all the fabricated DSSCs with Tithonia diversifolia having the highest at 1.56 %. Thus incorporating rGO in the TiO2 photo anode greatly improved the power conversion efficiency of the DSSC. Tithonia diversifolia dye had the highest efficiency which may be attributed to the concentration of the chlorophyll dye.

Effect of electron-donating and -withdrawing substitutions in naphthoquinone sensitizers: The structure engineering of dyes for DSSCs in Quantum Chemical Study

Dye-sensitized solar cells (DSSCs) are cost-effective photovoltaic devices that convert solar energy into electricity using a dye sensitizer, TiO2 photoanode, electrolyte, and counter electrode. This study investigates the impact of substituents on the performance of naphthoquinone-based dye sensitizers in DSSCs. We analyzed various naphthoquinone derivatives’ electronic structures and light absorption properties using DFT and TD-DFT. Our results demonstrate that electron-donating groups enhance DSSC performance by improving light absorption and electron injection. Specifically, naphthoquinone derivatives with methoxy (Dye-2) and methyl (Dye-3) groups showed superior properties. TD-DFT analysis revealed high molar extinction coefficients over a broad spectrum, making these dyes efficient at capturing sunlight. Additionally, these dyes effectively interact with TiO2, which is crucial for photostability and photovoltaic performance. In conclusion, naphthoquinone derivatives with electron-donating groups significantly improve DSSC performance, with Dye-2 and Dye-3 being strong candidates for high-performance applications.

Molecular Engineering Strategies of Spectral Matching and Structure Optimization for Efficient Metal-Free Organic Dyes in Dye-Sensitized Solar Cells: A Theoretical Study.

Metal-free organic dyes are promising dyes that can be applied widely in dye-sensitized solar cells (DSSCs). The rational design and selection of dyes with complementary absorption can promote the development of methods that can enhance the utilization of incident light by DSSCs, such as cosensitization and tandem devices. Based on these opinions, the structure of the reported high-performance metal-free organic dye ZL003 is used as a template to design two new metal-free organic dyes, HX-1 and HX-2, by replacing its donor unit with a 2-phenothiazine-phenylamine unit and fusing its three independent π-bridge units into a whole with the aim of driving the red shift and the blue shift of the absorption spectra of ZL003, respectively. Through theoretical investigation, it is demonstrated that the perfect complementary optical absorption of HX-1 and HX-2 can be realized as the shift of the absorption spectra of ZL003 to different directions, which means their feasibility to the application in cosensitization or tandem dye-sensitized solar cells (T-DSSCs). Furthermore, it is hypothesized that HX-1 may be the dye with better photovoltaic performance than ZL003 by modeling their intramolecular charge-transfer (ICT) processes, TiO2 surface adsorption, and photovoltaic parameters. The short-circuit current density (Jsc) and photoelectric conversion efficiency (PCE) of HX-1 are 23.10 mA·cm-2 and 21.26% in theory, compared to those of 20.68 mA·cm-2 and 19.64% in ZL003 at the same computational level, respectively. In view of the complementary optical properties, the combination of HX-1 with HX-2 may be a reasonable option for dyes for the development of a highly efficient cosensitization system or T-DSSCs in the future. In terms of such findings, these two novel metal-free organic dyes may have bright prospects in the research of highly efficient DSSCs, and this work can provide a reference for the design of dyes with complementary absorption through simple structural adjustments of the realistic dyes with high photovoltaic performance.

Photovoltaic performance enhancement via cocktail co-sensitization of D–A–π–A and D–π–A–π–A dyes in dye-sensitized solar cells

A novel organic dye (BIM37) featured with donor–auxiliary acceptor–π–acceptor (D–A–π–A) structure based on an acridine π–bridge has been designed and synthesized for dye-sensitized solar cells (DSSCs). Unlike the acridine-based D–π–A–π–A dyes (BIM25 and BIM26), BIM37 was obtained by inserting an auxiliary acceptor between the donor and π–bridge units. This modification leads to a significant red shift in the absorption spectrum compared to its counterparts. Thus, the DSSCs based on BIM37 achieved a power conversion efficiency (PCE) of 5.03%, which is higher than that of BIM25 (3.76%) or BIM26 (4.56%). To further improve the photovoltaic performance, the cocktail co-sensitization strategy was applied. In the presence of chenodeoxycholic acid (CDCA) as a co-adsorbent, the co-sensitized DSSC based on BIM37+BIM26 showed a high efficiency of 6.30%. This performance is superior to individual DSSCs with and without CDCA. The results show that molecular engineering for co-sensitization may be an effective strategy to improve the performance of DSSCs.

Investigating the effect of nitrogen and chlorine Co–doped carbon quantum dots in phenazine and quinoxaline sensitized solar cells

We investigated five dyes for dye-sensitized solar cells (DSSCs) relying upon derivatives of phenazine and quinoxaline and also studied their optical characteristics and the influence of functional groups such as (-CH3, -NO2, -C = O, -CN, and -OH) on these characteristics. When the prepared dyes are directly used at DSSCs, 9-Nitrobenzo[a]phenazin-5-ol (3b) dye device showed an improved Jsc (0.288 mA cm−2), Voc (0.437 V), FF (0.446), and η (0.056 %) than the sensitized solar cells by other dyes. In the following, nitrogen-doped carbon quantum dot and nitrogen, chlorine co-doped carbon quantum dot are used to improve the performance of DSSCs. The results showed that the device sensitized using the sensitizer (5-hydroxybenzo[α]phenazin-9-yl)(phenyl) methanone (3c)/NCQD has the highest photovoltaic efficiency with Jsc (0.979 mA cm−2), Voc (0.465 V), FF (0.370), and η (0.168 %). The N and Cl co-doped carbon dots were synthesized with a green approach to improve the performance of solar cells by the co-sensitization method. This approach is improving the efficiency of DCSSs with a simple, eco-friendly, and low-cost technique. Among the prepared sensitizers, (5-hydroxybenzo[α]phenazin-9-yl)(phenyl) methanone (3c)/N, Cl-CQD demonstrates the highest photovoltaic efficiency with Jsc (1.31 mA cm−2), Voc (0.495 V), FF (0.466), and η (0.303 %). FT-IR, XRD, 13C NMR, 1H NMR, TEM, EDS-Map, AFM, DLS, and PL studies were used to confirm the structure of the synthesized dyes and quantum dots.

Synthesis and characterization of new purple and green heterocyclic dyes for dye-sensitized solar cells

Due to the growing demand for energy from industrial activities, solar energy has gained increasing attention globally. In recent years, heterocyclic dyes have gained attention due to their potential use as organic photosensitizers in dye-sensitized solar cells (DSSCs). To develop new and effective synthetic dyes for DSSCs, a study was conducted to create new purple dyes 8-(4-chlorophenyl)-5-(hydroxyimino)-3H-imidazo[4′,5′:3,4]benzo[1,2-c]isoxazol-4(5H)-ylidene)-2-arylacetonitriles. These dyes were synthesized by reacting nitro derivatives of imidazo benzoxazole with arylacetonitriles in an alkaline media. Additionally, new fluorescent heterocyclic systems 3-(4-chlorophenyl)-6H-imidazo[4,5-a]isoxazolo[4,3-c]acridine-7-carbonitriles were obtained by heterocyclization of the purple dyes with SOCl2. The highest yield achieved in the synthesis of the title dyes is 74 %. The structures of the new purple and green heterocyclic dyes were confirmed through elemental analysis and spectroscopic data. The photophysical properties of the dyes were investigated using a UV–visible spectrophotometer and a fluorophotometer. The electrochemical characteristics of the purple dyes and fluorescent heterocyclic systems were also studied using cyclic voltammetry. The geometries of the dyes, as well as their highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, were determined through theoretical calculations using density functional theory (DFT). Furthermore, the photovoltaic performance parameters of the new dyes were examined by analyzing their incident photon-to-current efficiency (IPCE) spectra and current-voltage (I-V) curves. The experimental results showed that the purple dyes exhibited remarkable photovoltaic performances, up to 6.55 %.

Novel Zinc-porphyrin dyes for dye-sensitized solar cells that enables light capture in the near-ultraviolet and visible range

Two novel Zinc-porphyrin central dyes (T-5 and T-6) containing acetylene moiety have been designed and synthesized for application in dye-sensitized solar cells (DSSCs). The light-harvesting capabilities and photovoltaic performance of these dyes were investigated systematically through comparison of different donor (D) unit. Devices fabricated from phenoxazine (POZ)-based molecule T-5 showed higher short-circuit current (JSC, 11.32 mA cm-2) compared to T-6 which based on phenothiazine (PTZ) (10.1 mA cm-2) under standard global AM 1.5 G solar condition. This is due to the fact that the POZ unit has a greater electron supply capacity than the PTZ unit. The introduction of the acetylene moieties into the molecular structure broadens the light absorption range of the dye molecule to the entire visible range and the near-ultraviolet region. The conclusions of this paper demonstrate that incorporating strong electron donor groups in dye molecules, in synergy with conjugated groups, broadens the spectral range of light absorption, thereby enhancing the performance of the dye device.

The role of secondary donor in thiophene-based azo dyes for dye-sensitized solar cells and non-linear optics

The effect of altering the donating strength of secondary donors at the 4th position of the thiophene ring in a series of dyes labeled AB1 to AB9 is investigated in this study. According to the findings, the orientation of the secondary donor has a considerable impact on molecular planarity, resulting in changes in charge transfer (CT) properties within the thiophene-azo-benzoic acid backbone. The time-dependent density functional theory (TD-DFT) study supports these findings, indicating that the vertical absorption maximum of the dyes increases with the secondary donor's donating strength. From AB1 to AB5, photovoltaic parameters show an increase in DSSC performance. Furthermore, dye@TiO2 cluster experiments suggest the possibility of these dyes interacting with TiO2, resulting in red-shifted absorbance of dye@TiO2 clusters.Theoretical predictions are confirmed by the synthesis of AB1 to AB4, with initial absorption in dimethylformamide (DMF) and energies of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) following a similar pattern as observed in density functional theory (DFT) studies. TGA results show that AB1 to AB4 have remarkable thermal stability, enabling their practical application in DSSCs. The efficiencies of the constructed DSSCs varied, with AB4 having the highest (1.90 ± 0.1) and AB1 having the lowest (1.29 ± 0.1). Secondary donors play a critical role in determining molecular characteristics and device performance, according to the theoretical and experimental DSSC results.

Theoretical exploration of copper based electrolytes for third generation dye sensitized solar cells

Dye-sensitized solar cells (DSSCs) present a promising avenue for addressing the escalating need for clean energy solutions. These innovative cells offer a sustainable approach to meet the rising demands for environmentally friendly power sources. An assessment was conducted on a copper complex containing a hexadentate ligand, serving as a redox shuttle, alongside triphenylamine-based organic dyes in the construction of DSSC. This study thoroughly investigates the electronic structures, FMO, MEP surfaces, and photophysical properties of copper redox shuttle and triphenylamine dyes employing DFT and TDDFT calculations. The copper system, [Cu(bpyPY4)]2+/+, analyzed in this study, is anchored by the hexadentate polypyridyl ligand bpyPY4 (6,6′-bis(1,1-di(pyridine-2-yl)ethyl)-2,2′-bipyridine), scrutinized as a redox shuttle (RS). The assessed redox potential for [Cu(bpyPY4)]2+/+ is −4.67 eV. This indicates that the dye can effectively undergo regeneration by transferring electrons from the reduced form of the redox shuttle to the oxidized form of the dye. The photovoltaic efficiency has been analyzed with regard to various factors, including the energy gap between the HOMO and LUMO, the excited-state oxidation potential (Edye*), electron injection ability (∆Ginj), electron regeneration (∆Greg), light harvesting efficiency, short-circuit current density (JSC) and the open-circuit voltage (Voc). This study sheds light on present-day developments and forthcoming prospects in utilizing 3d transition metal-based redox shuttles, presenting them as compelling candidates for integration with organic dyes in Dye-Sensitized Solar Cells (DSSCs). This integration holds promise for more efficient solar spectrum absorption and enhanced performance of solar devices.

Unlocking the potential of anthocyanin-based dye-sensitized solar cells: Strategies for enhancing efficiency, stability, and economic viability

This study investigates the feasibility and potential of anthocyanins as natural dyes in dye-sensitized solar cells (DSSCs). The focus is on the efficiency, stability, and economic viability of using anthocyanins as green alternatives in renewable energy technology. While anthocyanins offer controlled modification of optical properties at a low cost, there are challenges to overcome in achieving high efficiency, long-term stability, and commercial affordability. The study analyzes recent research developments and proposes strategies to enhance efficiency, stability, and economic viability. Optimization techniques, such as dye mixing and co-pigmentation, as well as modifications to dye structure and protective coatings, are explored. Economic considerations, availability, scalability, and innovative approaches like dye engineering and novel device architectures are discussed. The findings highlight the potential of anthocyanin-based DSSCs as a sustainable and economically viable solar energy technology. The study concludes with recommendations for future research to overcome challenges and advance the field of anthocyanin-based DSSCs.

Comparative study of natural and synthetic dyes in DSSCs: An experimental and computational approach

This study explores the natural and synthetic dyes as sensitizers for dye-sensitized solar cells (DSSCs). Anthocyanin dye extract (PG) from pomegranate (Punica granatum) fruit, betanin pigment (BR) from beetroot (Beta vulgaris), and the commercially available organic dye, Rose Bengal (RB), were investigated as sensitizers for DSSCs and their photovoltaic performances were recorded. Density functional theory (DFT) and time-dependent DFT (TD-DFT) studies have also been performed in order to get insight into the photophysical and photoelectrochemical properties. The overall efficiencies (η) of 0.34%, 0.30%, and 0.25% were obtained for the PG, BR, and RB dyes under 1 sun illumination, respectively. The results infer that PG dye would act as a promising photo-sensitizer for DSSCs as compared to BR and RB sensitizers, which may be due to better interaction between anthocyanin molecule of pomegranate extract and TiO2.

Effects of Several Auxiliary Acceptors and Anchoring Groups on Charge Transfer and Photophysical Properties of D-A-π-A Type DSSCs: A DFT Study.

In this paper, we performed theoretical studies on the twelve D-A-π-A type organic dyes (G-1 ~ G-3, M-1 ~ M-3, J-1 ~ J-3, and S-1 ~ S-3) with 9-phenylcarbazole as the electron donor in anticipation of the application of these dyes in dye-sensitized solar cells (DSSCs). DFT and TD-DFT methods are applied to investigate in detail the molecular geometries, frontier molecular orbitals (FMOs), absorption spectra, charge density difference (CDD), and transition density matrix (TDM) of several dyes. The results show that the M-series (M-1 ~ M-3) dyes have the largest dihedral angles between the electron donor and the auxiliary acceptor and also has the largest energy gaps in HOMO-LUMO orbitals, which greatly reduces the charge transfer efficiency. Finally, the UV-Vis absorption spectra inferred that the anchoring groups modified with o-nitrobenzoic acid (G-3, M-3, J-3, S-3) can red-shift the absorption peaks of the dyes, which results in higher light-harvesting efficiency and improves the power conversion efficiency of DSSCs. Overall, all of these dyes contribute to the improvement of photovoltaic power conversion efficiency and have potential for application in DSSCs devices.

DFT study of the spectroscopic behaviour of different iron(II)-terpyridine derivatives with application in DSSCs

Through a comprehensive computational analysis utilizing Density Functional Theory (DFT), we clarify the electronic structure and spectroscopic properties of modified iron(II)-terpyridine derivatives, with the aim of enhancing the efficiency of Dye-Sensitized Solar Cells (DSSCs). We optimized a series of nineteen iron(II)-terpyridine derivatives and related compounds in acetonitrile (MeCN) as the solvent using TDDFT, evaluating their potential as dyes for DSSCs. From the conducted computations on the optimized geometries of the nineteen [Fe(Ln)2]2+ complexes, containing substituted terpyridine and related ligands L1-L19, we determined the wavelengths (λ in nm), transition energy (E in eV), oscillator strength (f), type of transitions, excited state lifetime (τ), light harvesting efficiency (LHE), frontier orbital character and their energies (ELUMO/EHOMO), natural transition orbitals (NTOs), injection driving force of a dye (ΔGinject), and regeneration driving force of a dye (ΔGregenerate). Results show that the theoretically calculated values for assessing dye efficiency in a DSSC correlate with available experimental values. The UV–visible spectra of [Fe(Ln)2]2+ exhibited a peak above 500 nm (λmax) in the visible region, attributed to the ligand-to-metal charge transfer band (LMCT) in literature, and a significant absorbance peak at approximately 300 nm (λA,max) in the UV region. The M06-D3/CEP-121G method replicated all reported λmax and λA,max values with a mean absolute deviation (MAD) of 21 and 18 nm, respectively. Our findings underscore the connections between electronic modifications and absorption spectra, emphasizing their impact on the light-harvesting capabilities and overall performance of DSSCs. This research contributes to the advancement of fundamental principles governing the design and optimization of novel photovoltaic materials, facilitating the development of more efficient and sustainable solar energy technologies.