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Photoexcitation Processes in Oligomethine Cyanine Dyes for Dye-Sensitized Solar Cellsa??Synthesis and Computational Study
摘要： We report density functional theory (DFT) calculations of three newly synthesized oligomethine cyanine-based dyes as potential TiO2-sensitizers in dye-sensitized solar cells. The three dyes have π-symmetry and the same acceptor side, terminating in the carboxylic anchor, but they differ through the π-bridge and the donor groups. We perform DFT and time-dependent DFT studies and present the electronic structure and optical properties of the dyes alone as well as adsorbed to the TiO2 nanocluster, to provide some predictions on the photovoltaic performance of the system. We analyze theoretically the factors that can influence the short circuit current and the open circuit voltage of the dye-sensitized solar cells. We examine the matching of the absorption spectra of the dye and dye-nanocluster system with the solar irradiation spectrum. We display the energy level diagrams and discuss the alignment between the excited state of the dyes and the conduction band edge of the oxide as well as between the redox level of the electrolyte and the ground state of the dyes. We determine the electron density of the key molecular orbitals and analyze comparatively the electron transfer from the dye to the semiconducting substrate. To put our findings in the right perspective we compare the results of our calculations with those obtained for a coumarin-based dye used in fabricating and testing actual devices, for which experimental data regarding the photovoltaic performance are available.
关键词： optical spectra,titanium dioxide cluster,dye-sensitized solar cells,oligomethine cyanine-based dyes,density functional theory
更新于2025-09-19 17:13:59
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Long lifetime g-C3N4 photocatalyst coupled with phosphorescent material working under dark condition
摘要： Existing photocatalysts suffer from decreased photocatalytic efficiency when illuminated at wavelengths beyond the UV region or in the absence of irradiation. To overcome this disadvantage, graphitic carbon nitride (g-C3N4), which is responsive to visible light, was coupled with a phosphorescent material (SEAD) that emits green light after irradiation is discontinued. The excited electron and holes in the as-made SEAD/g-C3N4 undergo slow recombination; thus, the material exhibited better performance than g-C3N4 based on photocurrent measurement. We demonstrated the performance of the samples via photodegradation experiments using three organic dyes; methylene blue (MB), methyl orange (MO), and rhodamine B (RhB). The results show that g-C3N4 coupled with the phosphorescent material exhibited better efficiency for photocatalytic degradation of organic dyes than g-C3N4 alone under dark condition as well as light irradiation. In addition, the decomposition of the dyes continued even after irradiation was discontinued, due to phosphorescence.
关键词： graphitic carbon nitride,Photocatalyst,recombination,degradation of organic dyes,phosphorescent material
更新于2025-09-19 17:13:59
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Spiro[fluorene-9,9a?2-phenanthren]-10a?2-one as auxiliary acceptor of D-A-??-A dyes for dye-sensitized solar cells under one sun and indoor light
摘要： Six novel organic dyes (RY1~RY6) containing spiro[fluorene-9,9'-phenanthren]-10'-one as an auxiliary acceptor were synthesised and effectively used for the fabrication of D-A-π-A type dye-sensitized solar cells (DSSCs). The molecular structures were modified by introducing a novel spiro[fluorene-9,9'-phenanthren]-10'-one auxiliary acceptor group between the donor and the π-bridge. The molecular rigidity can be enhanced by depressing intermolecular aggregation and carbonyl group can trapping the Li+ ions to retard the charge recombination. The sensitizer RY3 was found to perform remarkable light-harvesting efficiency of 6.30% at AM1.5 solar condition and 21.67% at TL84 (2500 lux) illuminations without DCA co-deposition. For further improvement, a higher efficiency can be achieved through a suitable co-sensitization of N719 and RY3, which displayed an efficiency of 8.55% under one sun (AM 1.5). While operated under indoor light, the efficiency was boosted to 25.57% and 27.04% at 1000 & 2500 lux illuminations, respectively. The high performance of co-sensitization of N719 and RY3 can be ascribed to a high surface coverage and a broader range of absorption wavelength. Stability test of the device co-sensitized with N719 and RY3 showed a mild decay of PCE 3.74% after 96 h, while it retained 84.49% of its original PCE after 336 h in ambient atmosphere without encapsulation.
关键词： Spiro[fluorene-9,9'-phenanthren]-10'-one,Co-sensitization,High performance under indoor light,Dyes sensitized solar cells
更新于2025-09-19 17:13:59
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Fusing Thienyl with N-Annulated Perylene Dyes and Photovoltaic Parameters for Dye-Sensitized Solar Cells
摘要： Due to the role of dye in dye-sensitized solar cells (DSSCs), design novel dye sensitizer is effective strategy to improve power conversion efficiency. To this end, the fundamental issue is the understanding sensitizer’s trilateral relationship among molecular structure, optoelectronic properties and photovoltaic performance. Here, on the one hand, to investigate the relationship between molecular structure and properties, 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, C278 and the dyes adsorbed on TiO2 clusters were calculated. It is found that, fusing thienyl to N-annulated perlyene can elevate the highest occupied molecular orbital (HOMO) energies, reduce orbital energy gap, increase density of states, expand HOMO to benzothiadiazole moiety, enhance charge transfer excitation, elongate fluorescence lifetime, amplify light harvesting efficiency and induce red-shift of absorption spectra. The transition configurations and molecular orbitals of dye adsorbed systems support that the electron injection in DSSCs based on these dyes are fast mode. On the other hand, to exposure the relationship between properties and performance, based upon extensive analysis of 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, which celebrate the quantitative bridge between the photovoltaic parameters and the electronic structure related properties. The results of this work are critical for design novel dye sensitizers for solar cells.
关键词： electronic structures,N-annulated perylene dyes,photovoltaic parameters,dye-sensitized solar cells,excitation properties
更新于2025-09-19 17:13:59
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Rational Design of Phenothiazine-Based Organic Dyes for Dye-Sensitized Solar Cells: The Influence of ??-Spacers and Intermolecular Aggregation on Their Photovoltaic Performances
摘要： Power conversion efficiency (PCE) is one of the important factors in influencing the overall performance of dye-sensitized solar cells (DSSCs), and precise prediction of PCE is a feasible strategy for preparing highly-efficient DSSCs devices. In this work, we designed a series of phenothiazine-based organic dyes by introducing different π-spacers including the 4-isopropyl-4H-dithieno[3,2-b:2′,3′-d]pyrrole (DTP) and 2,7-dihydronaphtho[1,2-d:5,6-d']diimidazole (NDI) to tune their photovoltaic properties. The present studies reveal that the PCE value of the DTP-based dye is estimated to 8.55%, in excellent agreement with the experimentally available value (8.19%) observed in the reported analogue. In comparison to DTP, the strong electron-deficiency NDI group induces a remarkable red-shifting of maximum absorption band, broadening the optical absorption into the near-infrared region. As a consequence, the NDI-based dye achieves an impressive PCE value of 15.51%, which is expected to be a potential organic dye applied in DSSCs.
关键词： Intermolecular aggregation,Phenothiazine-based organic dyes,π-spacers,Photovoltaic performances,Dye-sensitized solar cells
更新于2025-09-19 17:13:59
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Indoor Photovoltaics: Photoactive Material Selection, Greener Ink Formulations, and Slot-Die Coated Active Layers
摘要： Strong visible light absorption is essential to achieve high power conversion efficiency in indoor organic photovoltaics (iOPVs). Here, we report iOPVs that exhibit high efficiency with high voltage under excitation by low power indoor lighting. Inverted type organic photovoltaic devices with active layer blends utilizing the polymer donor PPDT2FBT paired with fullerene, perylene diimide, or ring-fused acceptors that are 6.5-9.1% efficient under 1 sun are demonstrated to reach efficiencies from 10-17% under an indoor light source. This performance transcends that of a standard silicon photovoltaic device. Moreover, we compared iOPVs with active layers both spin-cast and slot-die cast from non-halogenated solvents and demonstrate comparable performance. This work opens a path towards high efficiency iOPVs for low power electronics.
关键词： Organic Photovoltaics,Perylene Diimide Dyes,Conjugated Polymers,Roll-to-Roll Compatible Coating,Green Solvent Processing
更新于2025-09-16 10:30:52
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Investigation of triphenylamine-based sensitizer characteristics and adsorption behavior onto ZnTiO3 perovskite (101) surfaces for dye-sensitized solar cells using first-principle calculation
摘要： Four different Triphenylamine-based dyes, named as TPA-1, TPA-2, TPA-3 and TPA-4 as shown below, with substituents containing different linkages, earlier described inTiO2dye-sensitized solar cells(DSSCs), are described. The dyes are examined as potential dyes for perovskite ZnTiO3 based dye sensitized solar cells (DSSCs). The simulated characteristics include: Electronic absorption spectra, light harvesting efficiency, energy of dye adsorption to the semiconductor ZnTiO3 electrode, energy level alignment and spontaneity of charge transfer across the dye interfaces with ZnTiO3 and with solution redox couple. The characteristics have been comparatively investigated for all dyes. The absorption spectra for each dye, in its free and adsorbed forms, are discussed. Energy levels and electrochemical parameters are investigated to assess electron transfer efficiency between the excited dyes and the ZnTiO3 particles. Among the series, the dye TPA-3 shows superior behaviors, in terms of spontaneity of charge transfer with ZnTiO3 conduction band. The dye exhibits bidentate mode bonding with the semiconductor surface (101) as evidenced from its high adsorption energy. Such bonding enables stronger adherence between the dye and the semiconductor and enables more efficient charge transfer. The results encourage more theoretical and experimental study on TPA-3@ZnTiO3 DSSCs, with promising conversion efficiency and stability.
关键词： Dye-sensitized solar cells,DFT,Electronic absorption spectra,ZnTiO3 perovskite,Triphenylamine-based dyes
更新于2025-09-16 10:30:52
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Fluorescent 2-(pyridin-2-yl)vinyl pyridine dyes and their thermo-controlled release
摘要： The generation of unique thermosensitive fluorescent dyes via heteroaromatic Heck cross-coupling and N-pyridin-2-yl nucleophilic substitution was described. To demonstrate thermosensitive properties, the precursor was converted into carbonate or phosphate and heating at various temperatures and times of heating. Significant changes in fluorescence intensity and emission wavelengths, between carbonates and the cyclic product, were observed and proved that dyes may serve as removable fluorescent labels with large Stokes shifts (>80 nm). Application of thermosensitive fluorescent dyes in oligonucleotide labelling has been demonstrated.
关键词： Heck cross-coupling,large Stokes shifts,N-pyridin-2-yl nucleophilic substitution,thermosensitive fluorescent dyes,oligonucleotide labelling
更新于2025-09-16 10:30:52
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Exciton polaritons based on planar dielectric Si asymmetric nanogratings coupled with J-aggregated dyes film
摘要： Optical cavity polaritons, originated from strong coupling between the excitons in materials and photons in the con?ned cavities ?eld, have recently emerged as their applications in the high-speed low-power polaritons devices, low-threshold lasing and so on. However, the traditional exciton polaritons based on metal plasmonic structures or Fabry-Perot cavities suffer from the disadvantages of large intrinsic losses or hard to integrate and nanofabricate. This greatly limits the applications of exciton poalritons. Thus, here we implement a compact low-loss dielectric photonic – organic nanostructure by placing a 2-nm-thick PVA doped with TDBC ?lm on top of a planar Si asymmetric nanogratings to reveal the exciton polaritons modes. We ?nd a distinct anti-crossing dispersion behavior appears with a 117.16 meV Rabi splitting when varying the period of Si nanogratings. Polaritons dispersion and mode anti-crossing behaviors are also observed when considering the independence of the height of Si, width of Si nanowire B, and distance between the two Si nanowires in one period. This work offers an opportunity to realize low-loss novel polaritons applications.
关键词： exciton polaritons,dielectric Si asymmetric,TDBC J-aggregated dyes ?lm,nanogratings
更新于2025-09-16 10:30:52
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A Computational Protocol for Precise Prediction of Dye-Sensitized Solar Cell Performance
摘要： Numerous organic dyes have been developed for dye-sensitized solar cells (DSSCs). However, theoretical screening has not played the due role in designing new dyes. It is mainly attributed that there is rarely quantitative calculation and the inaccurate estimated values for short-circuit current density (JSC) and open-circuit photovoltage (VOC), especially for VOC. In this work, VOC is theoretically predicted by two different models for three D-π-A organic dyes (1, 2, and 3) with the same π bridge and acceptor as well as different donors. Although there is slight deviation for their structures, their properties are successfully differentiated by accurate quantitative calculations. Dimethoxybenzene substituted indoline is more suitable to be donor than methoxy substituted triphenylamine and methyl substituted indoline when it combines with 8H-thieno[2′,3′:4,5]thieno[3,2-b]thieno[2,3-d]pyrrole (TTP) as π bridge and cyanoacrylic acid as acceptor. The properties of donor not only are related with the core group but also are determined by the substituted group. Less than 10% deviation between theoretical and experimental results is an insurance to perform the reasonable prediction for photocurrent-photovoltage.
关键词： Short-circuit current density,Organic dyes,Computational protocol,Open-circuit photovoltage,Theoretical screening,Dye-sensitized solar cells
更新于2025-09-16 10:30:52