Pure Dye Research Articles

High stability photosensitizers for dye-sensitized solar cells: Synthesis, characterization and optical performance

Abstract The output of various donating substituents on the optical behavior of new photosensitizers in the solar cells was investigated. The pure intermediates and dyes were identified via an analytical procedure and confirmed the chemical structure. Zinc oxide and titanium dioxide were operated to fabricate the nanocrystalline layer of the solar cells. The UV–Visible spectra of all synthesized dyes on ZnO and TiO2 illustrated blue shift due to the J-aggregation of organic dyes on the semiconductor substrate. To predict the usability of dyes in the structure of the solar cells, two methods, DFT and CV were employed. Finally, the DSSCs devices were prepared based on synthesized dyes and ZnO or TiO2. The highest photocurrent was achieved for individual device-TiO2 sensitized with Dye 2 containing thioindigo and cyanoacrylic acid. The operation of photovoltaic device based on zinc oxide was lower than that of titanium dioxide.

Growth and impedance analysis of pure TGAc and dye doped TGAc crystals-enhanced dielectric permittivity for energy-storage devices

Herein, we delineate the enhancement of the dielectric properties of an anionic dye doped triglycine acetate crystal for the first time. Single crystals of pure triglycine acetate (TGAc) and reactive orange 16 (RO16) dye-doped (0.01, 0.03 mol%) triglycine acetate were synthesized with an intention to enhance the strengths of pure TGAc crystal using slow evaporation process. The crystalline structure and phase purity of the grown crystals were analyzed using Powder XRD studies. The frequency dependence of real and imaginary part of dielectric constant, loss tangent, real and imaginary part of impedance, electrical modulus and ac electrical conductivity have been investigated. The dielectric constant and dielectric loss for the grown crystals, have been found to decrease with increasing frequency. The decrease in permittivity and dielectric loss with an increase in applied field frequency is as per Maxwell–Wagner theory. The Cole–Cole plot implies that the mechanism of conduction is mainly due to bulk resistance. The enhanced dielectric constant of the doped crystals confirms the appropriateness of the developed crystals for energy storage capacitor applications.

Novel Carbon Quantum Dots/Silver Blended Polysulfone Membrane with Improved Properties and Enhanced Performance in Tartrazine Dye Removal

This study produced a novel polysulfone (PSF) membrane for dye removal using lemon-derived carbon quantum dots-grafted silver nanoparticles (Ag/CQDs) as membrane nanofiller. The preparation of CQDs was completed by undergoing hydrothermal treatment to carbonize the pulp-free lemon juice into CQD solution. The CQD solution was then coupled with Ag nanoparticles to form Ag/CQDs nanohybrid. The synthesized powders were characterized in terms of morphologies, functional groups and surface charges. A set of membranes was fabricated with different loadings of Ag/CQDs powder using the nonsolvent-induced phase separation (NIPS) method. The modified membranes were studied in terms of morphology, elemental composition, hydrophilicity and pore size. In addition, pure water flux, rejection test and fouling analysis of the membranes were evaluated using tartrazine dye. From the results, 0.5 wt % of Ag/CQD was identified as the optimum loading to be incorporated with the pristine PSF membrane. The modified membrane exhibited an excellent pure water permeability and dye rejection with improvements of 169% and 92%, respectively. In addition, the composite membrane also experienced lower flux decline, higher reversible fouling and lower irreversible fouling. This study has proven that the addition of CQD additives into membrane greatly improves the polymeric membrane’s properties and filtration performance.

Синтез и исследование новых азокрасителей на основе функционально замещенных производных салициловой кислоты

Three chromatographically pure azo dyes based on salicylic acid and para-nitroaniline were isolated in 60-64% yields. The structure of the synthesized compounds was proved by IR spectroscopy. The spectra of the compounds contain characteristic absorption bands associated with the vibrations of O–H, N–H, C=O, and N=N groups. The products precipitated as orange-brown powders, which corresponds to compounds with a short system of conjugated double bonds. The predominant tautomeric form of existence of the synthesized azo compounds was determined – 5,5'-(diazen-1,2-diyl)bis(2-hydroxybenzoic acid), 2-hydroxy-5-((4-nitrophenyl)-diazenyl)benzoic acid, 5-amino-2-hydroxy-4-((4-nitrophenyl) diazenyl) benzoic acid. It was shown that they all exist as azo-tautomers. To determine the dyeing power of potential dyes, a test cold dyeing was carried out on samples of a multichannel consisting of six main types of fabrics used in the textile industry, under conditions corresponding to dyeing with acid and reactive dyes. The ability of the compounds to act as acid dyes was established, coloring woolen, polyamide and acetate fibers in yellow-orange and beige-brown colors. The introduction of an amino group into the salicylic acid fragment weakens the color properties of the azo dye molecule. The calculation of the toxicity of compounds with intravenous and oral routes of administration, carried out according to the GUSAR program, shows their low toxicity (4-5 toxicity class). The introduction of an amino group into the azo dye molecule is accompanied by an increase in its toxicity. All isolated compounds comply with Lipinski's rule, which indicates their bioavailability. Prediction of the biological activity of the compounds, carried out using the PASS program, shows that with a probability of more than 90%, the synthesized compounds exhibit antiseptic properties without irritating the skin and mucous membranes. This allows the isolated compounds to be considered promising for use as dyes in cosmetics.

Enhanced Absorption Edge of Anchusa-Italica-Doped Pentacene towards Optoelectronic Applications

The dye-doped polymer is commonly used in the field of optoelectronics, given its effectiveness in optimising the device’s performance. This study is devoted to the synthesis and characterisation of Anchusa-Italica-doped Pentacene thin-film. Scanning electronic microscopy structural analysis, Fourier transform spectroscopy, and UV-visible transmittance spectra with a range of 300-900 nm were also carried out. The fundamental optical properties such as the absorption coefficient, optical energy gap, absorption and refractive indices were calculated based on the methods already used in the literature as Tauc’s relationship. The morphology of the samples indicated that dye structure was affected in the doped pentacene. The Fourier transform infrared technique (FT-IR) resulting spectrum of the doped samples also showed a significant absorption peak corresponding to C-H as an index of impurities. The calculated band-gap energy of the impurity sample was reduced and was the lowest compared to both the pure dye and polymer samples. The optical absorption and transmittance spectra revealed that it was positioned in the desirable ranges for optoelectronic applications. An anomaly in the absorption index was also observed through excitation of the resonance mode with transparent indication. This effect was deduced from the calculation of the refractive index. The results presented in this paper significantly contribute to the developments in the field of optoelectronic devices based on dye/polymer organic materials.

Fabrication and characterization of a novel polyvinyl alcohol-graphene oxide-sodium alginate nanocomposite hydrogel blended PES nanofiltration membrane for improved water purification

Novel asymmetric microporous polyethersulfone (PES)/polyvinyl alcohol-graphene oxide-sodium alginate (PVA-GO-NaAlg) nanocomposite hydrogel (HG) blended nanofiltration membranes with preferable characteristics were fabricated with the phase inversion induced by immersion precipitation technique. The hydrophilic PVA-GO-NaAlg nanocomposite hydrogel with carboxyl, hydroxyl, carboxylate ions and epoxy groups was in situ formed by chemical crosslinking in presence of the saturated boric acid and CaCl2 curing solution and characterized with SEM, XRD and FTIR analyses. Distinct quantities of the nanocomposite hydrogel were applied in the PES doping solutions for modifying membrane characteristics and the results were compared by pristine PES and PES/polyvinyl pyrrolidone (PVP) membranes. The prepared membranes characterization was performed using SEM, AFM, ATR-FTIR, water contact angle, overall porosity and mean pore radius measurement. Pure water flux, antifouling ability and dye rejection properties were also studied. By HG concentrations enhancement up to 1 wt%, the permeability of the membranes were improved and also antifouling ability of membranes were improved. The hydrogel blended membranes showed Lanasol blue 3R dye rejection more than 83%. Results of comparing PVP additive with HG indicated that the HG could increase hydrophilic property of membrane and result in permeability and antifouling ability improvement. On the other hand, the PVP additive has effective efficiency in membranes porosity and permeability improvement. Hence, the membrane by 1 wt% PVP and 1 wt% HG was fabricated for studying the coupling effect of these two additives, which indicated better solution flux and antifouling properties.

Thin-film composite nanofiltration membranes with high flux and dye rejection fabricated from disulfonated diamine monomer

Novel nanofiltration (NF) membranes with improved flux, dye rejection, high pH and temperature resistance were developed using a disulfonated diamine co-monomer, disodium-3-3′-disulfone-4-4′-dichlorodiphenylsulfone (S-DADPS). Thin film composite (TFC) NF membranes were fabricated on a porous polysulfone-based ultrafiltration support layer via the interfacial polymerization between trimesoyl chloride (TMC) in the organic phase and S-DADPS/piperazine (PIP) mixture in the aqueous phase. The effect of S-DADPS content was investigated on the structure and properties of fabricated TFC-NF membranes by varying the ratio between S-DADPS and PIP from 0/100 to 100/0 (w/w). The chemical structure, surface properties and the morphology of TFC-NF membranes were characterized by Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), optical profilometry, contact angle, and zeta potential measurements. Salt and dye rejection behaviors of fabricated TFC-NF membranes were evaluated using 2000 ppm MgSO4 and NaCl solutions and 100 ppm Setazol Red and Reactive Orange 16 dyes, respectively. Dyes were filtrated in acidic, neutral and alkaline conditions for pH resistance tests. The temperature resistance of membranes was evaluated using pure water and dye solutions at 15 °C, 25 °C, and 40 °C. Among all TFC-NF membranes fabricated by varying the S-DADPS/PIP ratio, the membrane with an 80/20 ratio of S-DADPS/PIP resulted in superior properties such as increased water flux without considerable salt and dye rejection loss compared to the neat TFC-NF membrane without S-DADPS. In addition, the variation of S-DADPS/PIP ratio was demonstrated as a powerful tool to tune the balance of flux, separation and rejection performance of NF membranes for custom purification purposes.

Enhanced optical, mechanical, photoacoustic and third-order nonlinear property of pure and crystal violet (CV) dye incorporated anthracene crystal: an efficacious material for nonlinear optical applications

Single crystals of pure and crystal violet (CV) dye-doped anthracene single crystals have been synthesized by solvent evaporation technique utilizing chloroform as the solvent. There is a significant enhancement in optical, mechanical, photoacoustical and third-order non-linear properties have been attained due to the incorporation of dye in the host material. The unit cell parameters and crystallinity of the grown crystals were examined using single crystal and powder crystal XRD analysis. The presence of various functional groups and mode of vibrational frequencies present in the grown crystal is determined using FTIR spectra. The doped crystal exhibits high optical transparency than pure which is evident in UV–Visible spectrum. Using Knoop hardness study the Young’s modulus value of pure and doped crystal is found to be 1.154 × 1010 Nm−2 and 1.394 × 1010 Nm−2. Doping of CV dye results in the enhancement of hardness number and various hardness parameters such as brittleness index, elastic stiffness constant and fracture toughness are calculated using Vicker’s microhardness study. Photoacoustic study depicts the thermal diffusivity value for the grown crystals and it is found to be 1.2505 × 10–6 and 3.128 × 10–6 for undoped and doped crystal respectively. The real, imaginary and third-order susceptibility of the doped crystal is prominent than undoped crystal were elucidated using Z-scan study.

A comparative study between MMT-Fe3O4/PES, MMT-HBE/PES, and MMT-acid activated/PES mixed matrix membranes

In this study, polyethersulfone (PES) nanofiltration mixed matrix membranes (MMMs) were fabricated utilizing different types of modified montmorillonite (MMT) (Fe3O4-montmorillonite (MMT-Fe3O4), acid activated-montmorillonite (MMT-AA), and hyperbranched epoxy-montmorillonite (MMT-HBE)). The morphological and physiochemical characteristics of prepared modified clay nanoparticles and membranes were defined using FTIR, XRD, FESEM, TEM, AFM, pure water flux and water uptake analysis, contact angle (CA) measurement, fouling studies, zeta potential determination, porosity measurements, mechanical properties assessments, and membrane performance evaluation. The results demonstrated that increment of clay nanoparticles' (NPs) weight ratio in PES membranes considerably improved membrane properties such as pure water flux, salt, dyes, and heavy metal removal due to membrane hydrophilicity. Generally, the membrane containing 3 wt% of additive possessed the best performance in terms of salt rejection, dyes and heavy metal elimination, and pure water flux. Membranes containing MMT-HBE showed significantly better heavy metal and dye removal performance than other membranes despite their lower water flux.

Grafting Thin Layered Graphene Oxide onto the Surface of Nonwoven/PVDF-PAA Composite Membrane for Efficient Dye and Macromolecule Separations.

This study investigates the permeance and rejection efficiencies of different dyes (Rhodamine B and methyl orange), folic acid and a protein (bovine serum albumin) using graphene oxide composite membrane. The ultrathin separation layer of graphene oxide (thickness of 380 nm) was successfully deposited onto porous polyvinylidene fluoride-polyacrylic acid intermediate layer on nonwoven support layer using vacuum filtration. The graphene oxide addition in the composite membrane caused an increased hydrophilicity and negative surface charge than those of the membrane without graphene oxide. In the filtration process using a graphene oxide composite membrane, the permeance values of pure water, dyes, folic acid and bovine serum albumin molecules were more severely decreased (by two orders of magnitude) than those of the nonwoven/polyvinylidene fluoride-polyacrylic acid composite membrane. However, the rejection efficiency of the graphene oxide composite was significantly improved in cationic Rhodamine B (from 9% to 80.3%) and anionic methyl orange (from 28.3% to 86.6%) feed solutions. The folic acid and bovine serum albumin were nearly completely rejected from solutions using either nonwoven/polyvinylidene fluoride-polyacrylic acid or nonwoven/polyvinylidene fluoride-polyacrylic acid/graphene oxide composite membrane, but the latter possessed anti-fouling property against the protein molecules. The separation mechanism in nonwoven/polyvinylidene fluoride-polyacrylic acid membrane includes the Donnan exclusion effect (for smaller-than-pore-size solutes) and sieving mechanism (for larger solutes). The sieving mechanism governs the filtration behavior in the nonwoven/polyvinylidene fluoride-polyacrylic acid/graphene oxide composite membrane.

Green synthesis of zinc oxide nanoparticles and zinc oxide–silver, zinc oxide–copper nanocomposites using Bridelia ferruginea as biotemplate

The quest to synthesize nanomaterials with improved properties, but less undesirable effects on the environment necessitated this research. Zinc Oxide (ZnO) nanoparticles and zinc oxide–silver (ZnO–Ag), zinc oxide–copper (ZnO–Cu) nanocomposites were synthesized with pure eco-friendly dye extracted from Bridelia ferruginea, zinc acetate (Zn(CH3COO)2) as host, copper acetate (Cu (CH3COO)2), and silver nitrate (AgNO3) as dopant precursors. Phytochemical screening of dyes showed high, presence of phenols and terpenoids. The nanomaterials were characterized by Fourier-transform infrared, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy and ultraviolet–visible spectroscopy. The results showed the capping agents in the dyes were responsible for reducing the bulk materials. The crystallinity of the nanomaterials were found to be 19.02, 18.98 and 18.90 nm for the ZnO, ZnO–Ag and ZnO–Cu nanoparticles respectively. The ZnO nanoparticles were flakelike in shape, whereas the Cu and Ag doped particles were spherical. An optical bandgap of 4.73 eV was recorded for the dye and 3.24 eV for the ZnO nanoparticles. This was narrowed to 3.18 and 3.13 eV by silver and copper dopant respectively. These results showed the nanoparticles as a potential agent for photovoltaics and other optical applications.

Design of AIEgens for near-infrared IIb imaging through structural modulation at molecular and morphological levels

Fluorescence imaging in near-infrared IIb (NIR-IIb, 1500–1700 nm) spectrum holds a great promise for tissue imaging. While few inorganic NIR-IIb fluorescent probes have been reported, their organic counterparts are still rarely developed, possibly due to the shortage of efficient materials with long emission wavelength. Herein, we propose a molecular design philosophy to explore pure organic NIR-IIb fluorophores by manipulation of the effects of twisted intramolecular charge transfer and aggregation-induced emission at the molecular and morphological levels. An organic fluorescent dye emitting up to 1600 nm with a quantum yield of 11.5% in the NIR-II region is developed. NIR-IIb fluorescence imaging of blood vessels and deeply-located intestinal tract of live mice based on organic dyes is achieved with high clarity and enhanced signal-to-background ratio. We hope this study will inspire further development on the evolution of pure organic NIR-IIb dyes for bio-imaging.

Spectral and energy characteristics of resonatorless lasing in solutions of Rhodamine 6G with nanoparticles of various nature with femtosecond pumping

The results of measurements of the spectral and energy characteristics of cavity-free lasing in Rhodamine 6G dye solutions with Al nanoparticles irradiated with femtosecond laser pulses are presented. A comparison is made of the threshold generation values in a pure dye solution and in a dye solution with nanoparticles upon irradiation with femtosecond pulses.

Effect of graphene oxide on modifying polyethersulfone membrane performance and its application in wastewater treatment

In the present paper, Graphene Oxide (GO) particles were prepared via Hummer method, and used in synthesis of composite membranes. Polyethersulfone (PES) nanocomposite membranes were synthesized via wet phase inversion technique, and using water as non-solvent. The membrane morphology was investigated using scanning electron microscopy (SEM). Change in the membrane surface hydrophilicity after modification was studied using contact angle measurements. The performance of fabricated PES nanocomposite membranes was measured by evaluating pure water flux, salt rejection, dye retention and heavy metals removal. The results indicated that by increasing the filler percentage up to 5 wt.%, the contact angle between the water droplet and the membrane surface was decreased and the droplet was more dispersed on the membrane surface which implies higher hydrophilicity of the prepared nanocomposite membranes. Moreover, the experimental results corroborated that addition of GO to the membrane significantly improved the pure water flux, salt rejection and heavy metals removal, and can be used as a novel methodology for preparation of high performance membranes in water treatment.

Effect of xylenol orange dye on morphological, optical, piezo-/di-electric and mechanical properties of potassium hydrogen phthalate single crystals

Pure and xylenol orange (XO; C13H32N2O13S;0.1 mol%) dye doped potassium hydrogen phthalate (KAP; C8H5KO4) crystal were grown by solution technique. Only {111‾} & {110} growth sectors of KAP crystal got selectively stained by the XO dye molecules with {010} being the largest visible (morphologically important) plane. Powder XRD pattern reveals that XO dyeing did not resulted in any extra Bragg peaks and hence, didn't changed the basic structure of KAP crystal (PCa21). HRXRD and etch pit density studies were performed to investigate the effect of XO dye staining on the crystallinity of KAP crystal.The Piezoelectric charge coefficient increased (1.42–1.62 pC/N), optical transparency increased (30%–50%), mechanical strength improved (10.2–11 kg/mm2 @ 20 g), dielectric constant enhanced (ε' ~40 to 44 @ 1 kHz) and dielectric loss decreased (~0.09 to ~0.02) due to XO dye doping. Comparative optical, mechanical, piezoelectric and dielectric investigations add to the scientific insights of KAP crystals and suggest XO-dyed KAP crystal as a better alternative than pure KAP crystal for opto-electronic devices applications.

Sodium hydroxide mediated alumina nanoparticles from waste aluminum foil sheets – Biological impact and photo-catalytic efficacy on commercial dyes

Herein, we reported a one-pot facile synthesis of alumina nanoparticles using waste aluminum foil sheet and sodium hydroxide by a simple solution method. The synthesized alumina nanoparticles were examined by UV Visible, X-Ray diffraction studies (XRD), Scanning Electron Microscope (SEM), and Energy Dispersive Analysis by X-rays (EDAX) to determine their size, shape, chemical nature and crystal structure. The average size of the alumina nanoparticles was found to be 50–70 nm. Besides the photocatalytic activity of alumina nanoparticles on two different commercial dyes, viz., MG and MB dyes were evaluated under UV light and naturally available daylight sources. The dye degradation percentages of MG dye under daylight irradiation are ∼17.7% and ∼94.8% under UV light irradiation, ∼14.8% and 90.1% for pure dye and alumina nanoparticles respectively. The percentage of degradation of MB dye in the presence of pure dye, alumina nanoparticles under daylight irradiation, and UV light irradiation are ∼19.6%, ∼92.6%, and ∼6%, 87.2% respectively. These results strongly authenticate the enhanced Photocatalytic activity due to efficient charge separation originating in the alumina nanoparticles. The alumina NPs exhibited an effective antibacterial activity against gram-positive and gram-negative bacteria and also showed an inhibition against human MCF-7 cancer cells, indicating its efficiency in the field of biomedical research.

Modification of the optical characteristics of Rhodamine B dye with different concentrations using gold nanorods

ABSTRACT The optical absorption and fluorescence of Rhodamine B dye solution with different dye concentrations, from 0.1 to 40 µM, in the presence of gold nanorods were studied. Colloidal gold nanorods were characterized by UV–Visible spectrophotometry and Transmission Electron Microscopy. Rhodamine B dye absorbance with and without gold nanorods was shown to be approximately constant, due to the dominance of the absorbance term of longitudinal surface plasmon resonance of gold nanorods. The fluorescence peak of dye-nanorods mixture with respect to that of pure dye was blue shifted. By increasing the dye concentrations, the energy transfer efficiency between the dye-nanorod pair was increased and, as a result, the fluorescence quantum yield was decreased. The results of the spectral overlapping of the absorption and the fluorescence spectra of RhB dye solution, with and without gold nanorods, matched well with the calculated energy transfer efficiency.

Preparation of molecular selective GO/DTiO2-PDA-PEI composite nanofiltration membrane for highly pure dye separation

The state-of-the-art graphene oxide (GO) has been wildly used in water purification due to its tunable nanoscale interlayer between the two-dimensional nanosheets. However, the structural instability and flux decline performances significantly limit the practical application of GO-based membranes. Herein, a novel GO/DTiO2-PDA-PEI (dopamine modified TiO2) composite nanofiltration membrane has been prepared via a multi-coupled strategy, combining with the self-assembly, copolymerization and surface grafting. Tuning the nanoscale interspace between the GO nanosheets, and constructing the membrane with positively charged surface and negatively charged subsurface, the loose GO/DTiO2-PDA-PEI composite nanofiltration membrane (GDP1P2-0.6 membrane with a mean pore size = 0.87 nm) show the filtration performance with water permeance as high as 41.6 L m−2 h−1 bar−1 and dye rejection around 99.9%, and the molecular selective factor (Eriochrome black T/Na2SO4) of α = 47.6. Long-term performance and stimulation have been investigated to further analyze the dye concentration and salt removing. The investigations demonstrate that the GO/DTiO2-PDA-PEI composite nanofiltration membrane enriches 14.9-fold Eriochrome black T (ET) and reduces Na2SO4 to 0.36% in the term of the concentration factor 15 and batch diafiltration factor 5.

A study on the utility of immobilized cells of indigenous bacteria for biodegradation of reactive azo dyes

Azo dyes are recalcitrant compounds used as a colorant in various industries. The pollution caused by their extensive usage has adversely affected the environment for years. The existing physicochemical methods for dye pollution remediation are rather inefficient and hence there is a dearth of low-cost, potential systems capable of dye degradation. The current research studies the biodegradation potential of immobilized bacterial cells against azo dyes Reactive Orange 16 (RO-16) and Reactive Blue 250 (RB-250). Two indigenous dye degrading bacteria Bacillus sp. VITAKB20 and Lysinibacillus sp. KPB6 was isolated from textile sludge sample. Free cells of Bacillus. sp. VITAKB20 degraded 92.38% of RO-16 and that of Lysinibacillus sp. KPB6 degraded 95.36% of RB-250 within 72 h under static conditions. Upon immobilization with calcium alginate, dye degradation occurred rapidly. Bacillus. sp. VITAKB20 degraded 97.5% of RO-16 and Lysinibacillus sp. KPB6 degraded 98.2% of RB-250 within 48 h under shaking conditions. Further, the nature of dye decolorization was biodegradation as evident by high-performance liquid chromatography (HPLC), and Fourier-transform infrared spectroscopy (FTIR) results. Phytotoxicity and biotoxicity assays revealed that the degraded dye products were less toxic in nature than the pure dyes. Thus, immobilization proved to be a highly likely alternative treatment for dye removal.

An electron donating controlling strategy for design several dithieno[3,2-b:2′,3′-d]pyrrole based dyes with D–D–A structure in dye-sensitized solar cells

One of the important strategies for designing pure organic dyes is to improve the electron donating abilities of dye donors hence increase the intramolecular potential energy difference. In order to quantify the electron-donating capacity of organic units, we firstly propose a parameter donation ability (DA) value for evaluating the electron DA of organic units via theoretical calculation, by using of several fragments such as coplanar dithiophenyl pyrrole, triphenylamine (TPA), phenothiazine (PTZ) and cyanoacetic acid (CA) which is the research objects here. Inspired by the DA values of the above organic fragments, dye PSD-9, PSA-10 and PST-11 were designed and synthesized. Cyclic voltammetric (CV) measurements show that the DA values of dye PSA-10 and PST-11’s donor increases when TPA and PTZ groups are introduced into PSD-9, hence HOMO level increases and the band-gap narrow down. This change is reflected in the absorption spectra: the maximum absorption wavelength of PSA-10 and PST-11 is 63 and 84 nm red-shifted compared with PSD-9. Similarly, the molar extinction coefficients of PSA-10 and PST-11 are increased by 34.7 × 103 and 14.7 × 103 M−1 cm−1, respectively. Combining a mesoporous titania film grafted by these dithiophenyl pyrrole dye with iodine electrolyte, an 4.2% and 4.8% power conversion effciency (PCE) is achieved for PSA-10 and PST-11 at an irradiance of the AM1.5G sunlight, with an significant increasing compared to PSD-9 with an PCE of 1.6%. The typical photocurrent density–voltage (J–V) test shows that the short circuit current of dye PSA-10 and PST-11 is much higher than that of PSD-9, which is the main reason for the improvement of PCE. The red-shift and stronger IPCE curve is the most advantageous evidence of the change of short circuit current. Furthermore, electrochemical impedance measurements is studied for exploring the changes of open-circuit voltage of PSA-10 and PST-11, the results infer that larger donor units and long alkyl chains can effectively increasing current density on photoanode, hence increase the open circuit voltage of the devices.