Organic Dye Sensitizers Research Articles

Effect of Thiophene-Hydrazinyl-Thiazole derivative as an efficient dye sensitizer and performance enhancer of TiO2 toward rhodamine B photodegradation

Visible-light-driven photocatalysis is an eco-friendly technology for wastewater treatment, where TiO2-based photocatalysts displayed outstanding performance in this regard. Dye sensitization is a promising approach for overcoming the common drawbacks of TiO2via improving its photocatalytic performance and extending its activity to visible light. Herein, we demonstrate the synthesis of the Thiophene-Hydrazinyl-Thiazole (THT) derivative as a novel organic dye sensitizer to be employed as a visible-light antenna for TiO2 nanoparticles. The physicochemical characteristics of the as-synthesized TiO2-based nanoparticles are examined by different techniques, which revealed the successful fabrication of the proposed THT-TiO2 heterojunction. The incorporation of THT molecules on the TiO2 surface led to slight disorders and deformation in the crystal lattice of TiO2, a remarkable improvement of its absorption in the visible light as a perfect visible-light antenna in the whole visible region, and significant enhancement in the charge transfer. Rhodamine B (RhB) is used as an organic dye model to assess the photocatalytic efficiency of the as-fabricated THT-TiO2 photocatalyst which achieved almost complete degradation (>95% in 150 min) with an observed rate constant (kobs) of 0.0164 min−1; total organic carbon (TOC) measurements suggested ∼75% mineralization. THT-TiO2 achieved 2.1-fold enhancement in photodegradation% and 4.1-fold enhancement in kobs compared to the bare TiO2. THT showed good activity under visible-light irradiation (RhB degradation% was >66% in 150 min and kobs = 0.0085 min−1). The influence of the initial pH of the solution was investigated and pH 4 was the optimum pH value for suitable interaction between RhB and the surface of THT-TiO2. Radical quenching experiments were conducted to assess the crucial reactive species where the ∙OH and O2.− were the most reactive species. THT-TiO2 showed promising stability over three successive cycles. Finally, the improvement mechanism of the photocatalytic activity of THT-TiO2 was attributed to the electron injection from the excited THT (the dye sensitizer) to TiO2 and enhanced charge separation.

Enhancing dye sensitized solar cells performance through quinoxaline based organic dye sensitizers

Enhancing dye sensitized solar cells performance through quinoxaline based organic dye sensitizers

Metal-free phenothiazine dyes with alkoxy chains modified at different position for dye-sensitized solar cells

Long alkyloxy or alkoxyphenyl chains are commonly introduced to organic dye sensitizers in dye-sensitized solar cells (DSSCs) to inhibit the aggregation of sensitizer on the TiO2, thereby minimizing charge recombination. Here, we synthesized four D-D-π-A sensitizers (TP-C6, TP-PhOC6, C6O-TP-C6, C6O-TP-PhOC6), that feature alkyl-/alkoxyphenyl- moiety in phenothiazine (PTZ) donor’s N-position, and either alkoxy or no alkoxy groups in triphenylamine (TPA) auxiliary donor. Then, their photophysical, electrochemical and DSSCs properties were investigated. The UV-Vis and electrochemical studies revealed that all four dyes exhibited good light absorption ability and appropriate HOMO-LUMO energy levels. The introduction of alkoxy at the donor or auxiliary donor can result in a significant redshift in absorption. Among them, TP-PhOC6, which incorporates an alkoxy phenyl group at the N-position of PTZ and lacks alkoxy in TPA, induces a greater redshift in ICT absorption with strong absorption intensity. Additionally, in TP-PhOC6 based DSSC, mitigated charge recombination was observed. As a result, this device exhibited the strongest and widest IPCE spectrum, the highest Jsc (12.77 mA/cm²) and Voc (0.85 V), leading to the highest PCE (6.59 %).

Enhancing the performance of pyridyl carboxamide-N,N-dimethyl amino chalcone (PCC) as a dye sensitizer for dye-sensitized solar cells (DSSCs) through the incorporation of electron donor moieties

This study has focused on enhancing the performance of pyridyl carboxamide-N,N-dimethyl amino chalcone (PCC) as a sensitizer for dye-sensitized solar cells (DSSCs) by strategically incorporating electron donor moieties identified in a literature review. Our reviewing the previous reports highlights the pivotal role of electron donors in optimizing light harvesting, electron injection, and overall power conversion efficiency in organic dye sensitizers, particularly those following a donor-bridge-acceptor (D-π-A) architecture. The selected donor moieties, including dithieno[3,2-b:2′,3′-d]thiophene (DTT), benzodithiophene (BDT), triphenylamine (TPA), carbazole (CBZ), and triazatruxene (TAZ), are systematically introduced into the molecular structure of PCC (abbreviated as PCC-DTT, PCC-BDT, PCC-TPA, PCC-CBZ, and PCC-TAZ, respectively). The performance of these modified compounds is rigorously evaluated using density functional theory (DFT) methods. Validation results revealed that the most reliable method for PCC derivative characterization involved the combination of the functional B3PW91 with a 6-31G(d) basis set. The results indicate that the incorporation of certain donor moieties, particularly BDT, significantly enhances the electronic and optical properties of PCC, including lower HOMO energy levels, a narrow energy gap (Egap), enhanced absorption intensity, and a redshift in absorption peaks. Evaluation of photovoltaic properties including electron injection (ΔGinj), and open circuit voltage (Voc), indicated facilitating spontaneous electron injection from the dyes to the TiO2 conduction band. Notably, PCC-TAZ demonstrated the lowest electron regeneration (ΔGreg), suggesting a notable potential for efficient electron regeneration.

Computational Study on D-π-A-Based Electron Donating and Withdrawing Effect of Metal-Free Organic Dye Sensitizers for Efficient Dye-Sensitized Solar Cells

A new generation of metal-free organic dyes with a range of donor (D1) and acceptors (A1-A3) were designed and examined for dye-sensitized solar cells (DSSCs) based on (3a) dye as a literature. Triphenylamine (TPA), thiophene ([Formula: see text] and 2-cyanoacrylic acid groups each perform the roles of an acceptor (A), donor (D) and spacer in order to produce a D-[Formula: see text]-A system. To investigate the intramolecular charge transfer (ICT), electronic distribution, ultra-violet visible (UV–Vis) absorption wavelengths, molecular electrostatic potential (MEP) and photovoltaic (PV) parameters of the D1 and A1–A3 molecules, density functional theory (DFT) and time-dependent DFT (TD-DFT) were used. The classification of the tunable donor D1 and A1–A3 determines the PV performance of the dye molecules. Results show that the A2 dye replacement group increases the performance of PV cells via red-shifting absorption spectra. Also, when compared to 3a, A2 dye have lower energy gap ([Formula: see text] and superior UV–Vis spectra that cover the full visible range. These results demonstrate the viability of molecular tailoring as an approach to improve D-[Formula: see text]-A sensitizer proposal for efficient DSSCs fabrication.

Panchromatic Pt/TiO2-Based Photocatalysts Sensitized with Carboxylated Chlorin Dyads for Water Splitting Hydrogen Evolution

Harvesting and converting solar energy into hydrogen production provides a new strategy for the global energy crisis. Since TiO2, the most widely used photocatalyst, absorbs light limited in ultraviolet region, extension of photo-response in visible to near-infrared region by dye-sensitization of TiO2 photocatalysts has attracted more and more attention in the field of artificial photosynthesis. In this work, three chlorophyll(Chl)-related sensitizers were designed to realize panchromatic light-absorption to simulate the charge separation process in natural photosynthetic reaction centers. The dyad sensitizers were synthesized by covalently-linking two different types of chromophore units derived from natural Chls-a/b, and their effects of Pt/TiO2-based photocatalysts for water splitting hydrogen evolution reaction (HER) were investigated. The Pt/TiO2 composite sensitized with Chl-a type dyad showed the best photocatalytic HER performance, and the H2 evolution of 5.4 mmol g-1h-1 was achieved. Electronic absorption, fluorescence emission, and time-resolved photoluminescence spectra as well as photocurrent responses and electrochemical impedance measurements were used to reveal the key factors of dyad sensitizers that influence the performances of Pt/TiO2 based photocatalysts. This work provides insights to explore new organic dye-sensitizers for improving the performance of TiO2-based photocatalysts.

Synthesis and Characterization of a Metal-Free Organic Dye-Sensitizer for Solar Cell: An Advanced Organic Chemistry Research-Based Laboratory

A multistep synthesis of a metal-free organic dye-sensitizer for solar cells was developed as a multifaceted research project for upper-division undergraduate students with a goal of introducing students to the application of organic synthesis in material science, and renewable energy research. The characterization of the dye is done by thin-layer chromatography (TLC), NMR, IR, melting point, UV–vis spectroscopy, fluorescence spectroscopy, and cyclic voltammetry.

Electrical Performance of Dye Sensitized Solar Cell with the Extracts of Swamp Land Vegetation as Organic Dye Sensitizer

The electrical performance of dye sensitized solar cell with the extract of swamp land vegetation was conducted based on the extracts of bluebell (Ruellia tuberosa L.), flowers of ulam raja (Cosmos caudatus Kunth), and leaves of water spinach (Ipomoea aquatica). The electrical characteristics of DSSC was different for each dye sensitizer. The difference in electrical characteristics of DSSCs in the range of lighting source intensity 445 W/m2 - 845 W/m2 generated from solar lighting sources is generally higher than that generated from halogen lamp. Efficiency (η) of the conversion of light into electricity produced by DSSCs whose lighting sources from halogen lamps tend to decrease with the decreasing intensity of lighting sources, except for extract leaves of water spinach. The efficiency of the conversion of light into electricity produced by DSSC for extract leaves of water spinach on halogen lamps with the intensity of lighting sources 445 W/m2, 205 W/m2, and 100 W/m2, respectively 0.284%; 0.483%; and 0.983%.

Properties of Chlorophyll Based Organic Dye Sensitizer Molecule Extracted in Various Solvents

Properties of Chlorophyll Based Organic Dye Sensitizer Molecule Extracted in Various Solvents

Donor functionalized perylene and different π-spacer based sensitizers for dye-sensitized solar cell applications - a theoretical approach.

A series of perylene-based novel metal-free organic dye sensitizers are designed and optimized for dye-sensitized solar cell (DSSC) applications. The electronic and optical properties are analyzed through density functional theory (DFT) and time-dependent density functional theory (TD-DFT) approach. For perylene-based donors, the effects of additional donor units and different π-spacer positions were investigated. Cyanovinyl and thiophene are used as π-spacers, dimethylamine (DM) and N-N-dimethylaniline (DMA) are used as additional donors, and cyanoacrylic acid is used as mono acceptor unit for the designed sensitizers. Natural bonding orbitals (NBOs), frontier molecular orbitals (FMO), UV-Vis, and nonlinear orbital analysis were predicted to find the net electron transfer, energy gap, absorption spectra, and electronic charge distribution for perylene-based dye sensitizers, respectively. The electron injection and electron regeneration properties were also analyzed for perylene-based sensitizers.

Synergistic role of aluminium sulphate flocculation agent as bi-functional dye additive for Dye-Sensitized Solar Cell (DSSC)

In this study, an organic dye sensitizer derived from blackberry fruits was employed, and the influence of aluminium sulphate, Al2(SO4)3·H2O (alum) as a bi-functional (acidification and flocculation) additive in DSSC was investigated. The alum treated dye solution, ATD, was created by adding 0.1 g alum to the dye solution prior to the immersion operation. As reference, an untreated dye solution, UD, was created for comparative purposes. The TiO2 photoelectrodes were characterized through FESEM, EDXs, and XRD techniques, while the dye properties were investigated using UV-Vis and FTIR. Finally, I-V characteristic, IPCE and EIS measurements were used to assess the overall performances of DSSCs. Based on the findings, the photocurrent-voltage conversion efficiency of the ATD, and the non-treated (UD) dye sensitised DSSCs were found to be 0.64 ± 0.02% and 0.44 ± 0.02%, respectively. The role of alum in regulating the acidity of the blackberry dye solution in the ATD photoelectrode mimics the acid treatment process on TiO2 nanoparticles. Furthermore, the purification process of natural dye solution by the flocculation reaction of crude impurities (sugar, protein, etc.) purifies the dye solution even further. The ATD DSSC outperformed the UD by 45.50 ± 0.02% as a result of these combined effects.

Enhancing Rechargeable Persistent Luminescence via Organic Dye Sensitization.

Owing to their unique afterglow ability, long-wavelength light activatable persistent luminescence (PersL) nanoparticles (PLNPs) have been emerging as an important category of imaging probes. Long-wavelength LED light has been shown to be effective in recharging these nanoparticles. However, finding a simple and effective method to amplify such renewable PersL signals under long-wavelength light is still a key challenge. Herein, we discovered that a dye-sensitization strategy was able to effectively boost the renewable PersL signals of the NIR emitting ZnGa2 O4 :Cr3+ (ZGC)) under long-wavelength LED light. Moreover, as a proof-of-principle tumorectomy demonstration, this new class of dye sensitized ZGC enabled simultaneous intraoperative anatomic tumor navigation and effective microscopic detection of tumor cells in pathological diagnosis.

Enhancing Rechargeable Persistent Luminescence via Organic Dye Sensitization

AbstractOwing to their unique afterglow ability, long‐wavelength light activatable persistent luminescence (PersL) nanoparticles (PLNPs) have been emerging as an important category of imaging probes. Long‐wavelength LED light has been shown to be effective in recharging these nanoparticles. However, finding a simple and effective method to amplify such renewable PersL signals under long‐wavelength light is still a key challenge. Herein, we discovered that a dye‐sensitization strategy was able to effectively boost the renewable PersL signals of the NIR emitting ZnGa2O4:Cr3+ (ZGC)) under long‐wavelength LED light. Moreover, as a proof‐of‐principle tumorectomy demonstration, this new class of dye sensitized ZGC enabled simultaneous intraoperative anatomic tumor navigation and effective microscopic detection of tumor cells in pathological diagnosis.

Innenrücktitelbild: Enhancing Rechargeable Persistent Luminescence via Organic Dye Sensitization (Angew. Chem. 29/2021)

Innenrücktitelbild: Enhancing Rechargeable Persistent Luminescence via Organic Dye Sensitization (Angew. Chem. 29/2021)

Optimizing the performance of dye-sensitized upconversion nanoparticles

Upconversion nanoparticles (UCNPs) are promising for bioimaging, sensing, and other applications, but their upconversion (UC) efficiency is far from satisfactory. Organic dye sensitization is considered to be an effective strategy to improve the performance of UCNPs. In this work, we provide direct evidence that organic sensitizer surpasses inorganic sensitizer in sensitization capability. To maximize the performance of dye-sensitized UCNPs, three critical factors, namely different optically inert lanthanide ions, Yb3+ doping concentration, and particle size, are systemically investigated and optimized. It is found that the optimal Yb3+ doping concentration and particle size are determined to be 20% and ~19 nm for dye-sensitized UCNPs, while different optically inert lanthanide ions have negligible influence on this system. Importantly, our results suggest that dye sensitization is more favorable for improving the performance of smaller-sized UCNPs. Although ultrasmall UCNPs (<10 nm) are desirable for biomedical applications UCNPs due to their reduced toxicity, they suffer from extremely low UC efficiency and weak brightness. Fortunately, the strategy of dye sensitization turns out to be particularly useful for producing ultrasmall and ultrabright UCNPs, which are desirable for biomedical applications.

Effect of Mn2+ Substitution into the Host Lattice of ZnO via sol–gel Route for Boosting the Dye-Sensitized Solar Cells Performance

In this study, Mn2+ ion is doped in ZnO lattice framework at 1, 3 and 5 wt % by a simple and low-cost sol–gel route to attain improved optoelectronic response. The structural investigation by XRD and Raman analysis explores the formation of hexagonal wurtzite framework with variations in lattice parameters comprising peak intensities favors the Mn doping. The extent of doping was supported by EDS analysis, while XPS confirms doping in + 2 chemical state. The optical investigation by UV–visible and PL provides prominent peaks that also specify peak shifting in order of doping level, while the significant hexagon-shaped nanoparticle (NP) formation was deduced in SEM and TEM micrographs. These proficient ZnO NPs have been deposited on fluorine-doped tin oxide (FTO) conducting glass plate by doctor-blade technique to get photoanodes. The electrical performance of these photoanodes especially photocurrent generation was investigated under standard AM 1.5 one sun illuminations. The highest photoconversion efficiency was attained for 3% Mn-doped ZnO photoanode after xanthene-based organic dye sensitization with output efficiency (η%) of 0.25% higher than 0.03% of bare ZnO. The comparable ionic radii with exactly half-filled 3d orbital simply overlap with the ZnO valence bond responsible for enhanced overall structural and optical properties that beneficial for DSSCs performance.

Eosin Y Covalently Modified on Graphene Oxide for Enhanced Photocatalytic Activity toward the Degradation of Antibiotic Cefaclor under Visible Light Irradiation

AbstractThe covalent immobilization of eosin Y (EY) on graphene oxide (GO) was prepared and the obtained GO/EY composite can be used as a visible‐light‐driven photo‐catalyst for the degradation of cefaclor (CEC) antibiotics. The GO/EY composite exhibited much higher photocatalytic activity than pure GO and EY adsorbed GO. Using 2 mg L−1 of CEC at pH=7, 97 % degradation toward CEC could be achieved after irradiation time of 45 min. The enhanced photocatalytic activity for GO/EY composite can be attributed to the modification of GO by EY, which acted as a sensitizer for enhancing visible light absorption. The affecting factors of photocatalytic activities on the photocatalytic degradation of CEC were evaluated, including the effects of pH values, the photosensitized oxidation conditions and the reusability of the photocatalyst. Furthermore, the enhanced photocatalytic mechanism induced by visible‐light responsive GO/EY composite was proposed by reactive specie trapping experiments, and 1O2 and H2O2 were determined to be the main reactive oxygen species in the photocatalytic system. All these results demonstrated that organic dye sensitizer functionalized GO provided a nice candidate as a photocatalyst for the removal of CEC antibiotic from water under visible light irradiation.

Acceptor substituent effect on triphenylamine-based organic dye sensitizers for DSSCs: quantum chemical study

In this work, a series of triphenylamine (TPA)- based dye molecules (A1–A5) for dye-sensitized solar cells (DSSCs) application has been designed and screened. The electron donor contains TPA, thieno[3,2-b]thiophene, as the π-bridge, cyanoacrylic acid as electron acceptor based on donor–π-spacer–acceptor (D-π-A) as reference dye (3a). In order to enhance the tuning, effect of acceptor moieties was investigated at 3a dye. The electron acceptor effect of the substituent on the absorption spectra and photovoltaic (PV) properties has been investigated by the combination of density functional theory (DFT) and time-dependent DFT (TD-DFT) method approaches. Different exchange-correlation (XC) functionals were initially evaluated in order to establish a proper methodology for calculating the excited state energy of the 3a dye. Consequently, TD-ωB97XD method and 6-31G(d) basis set have used the comparison of experimental value. From the calculated results, it was concluded that the A4 (PO3H2) and A5 (SO2H) dyes are strongly grouped for more red-shift and electrons injected into semiconductor the conduction band edge of TiO2 was successful. It is expected that our research will pave a new method to design efficient organic D-π-A dye sensitizers in DSSCs.

Absorption spectra and transition states for new organic dye sensitizers based on anthracene

Anthracene is the backbone of three suggested organic compounds in present work. Our calculations depending on DFT and TD-DFT take on B3LYP hybrid function using the basis sets 6-31g to carry out some properties at the ground state electronic and photovoltaic properties for the studied compounds. The relax structures show all the compounds have quasi planar conformation. The results showed that Homo and Lumo are little different, suggesting that be different structures play substantial characters to increase an electron acceptance. The result of( Lumo-Homo) gap and the voltage of open circuit are the factors operating to refining the quality for devices of solar cells. Furthermore, due to the high probability of the process for an electron injection of the organic structure in the TiO2 conduction band, where the energy of maximum absorption and the wavelength are occur in the range spectrum of the solar.

Fusing Thienyl with N-Annulated Perylene Dyes and Photovoltaic Parameters for Dye-Sensitized Solar Cells.

Due to the role of dyes in dye-sensitized solar cells (DSSCs), designing novel dye sensitizers is an effective strategy to improve the power conversion efficiency. To this end, the fundamental issue is understanding the sensitizer's trilateral relationship among its molecular structure, optoelectronic properties, and photovoltaic performance. Considering the good performance of N-annulated perlyene dye sensitizers, the geometries, electronic structures, and excitations of the selected representative organic dye sensitizers C276, C277, and C278 as well as dyes adsorbed on TiO2 clusters were calculated in order to investigate the relationship between molecular structures and properties. It was found that fusing thienyl to N-annulated perlyene can elevate the highest occupied molecular orbital (HOMO) energy, reduce the orbital energy gap, increase the density of states, expand the HOMO to the benzothiadiazole moiety, enhance the charge transfer excitation, elongate the fluorescence lifetime, amplify the light harvesting efficiency, and induce a red-shift of the absorption spectra. The transition configurations and molecular orbitals of the dye-adsorbed systems support that the electron injection in DSSCs based on these dyes is a fast mode. Based on extensive analysis of the electronic structures and excitation properties of these dye sensitizers and the dye-adsorbed systems, we present new quantities as open-circuit voltage and short-circuit current density descriptors that celebrate the quantitative bridge between the photovoltaic parameters and the electronic structure-related properties in order to expose the relationship between properties and performance. The results of this work are critical for the design of novel dye sensitizers for solar cells.