This study aimed to characterize novel complex coacervates based on Zedo gum and cress seed gum as natural polysaccharides with gelatin (type-A and type-B) as potential wall materials for ...encapsulation of anthocyanins. The coacervates were prepared under optimum conditions (pH and gum to gelatin ratio), freeze-dried, and the resulted powders were analyzed in terms of thermal stability, morphology, and molecular interactions. The thermogravimetric analysis revealed that molecular interaction between polysaccharides and gelatins led to enhance the thermal stability of gums. The morphology of coacervates showed that while ZG-gelatin and CSG-gelatin coacervates resulted in cubic and irregular particles, freeze-drying severely changed the morphology of coacervates. Moreover, SEM images at lower magnification showed big voids for lyophilized coacervates, while SEM images confirmed a compact and dense microstructure of coacervates at higher magnification and BET method. Also, the molecular interaction of polysaccharides and gelatin in aqueous media was assessed using Raman spectroscopy. Furthermore, findings showed that the type-A of gelatin is a more suitable protein to form coacervates with polysaccharides. In the next step, natural anthocyanins from barberry were encapsulated by proposed coacervates as wall material. The encapsulated extract had elevated thermal stability and showed a lower degradation rate.
•Formed coacervates had enhanced thermal stability compared to gums.•All coacervates could encapsulate anthocyanin and improve its thermal stability.•ZG lead to denser coacervates while CSG was better heat protector for anthocyanin.•The molecular interaction between biopolymers was confirmed by Raman spectroscopy.•Gel-A was a more suitable protein to form coacervates compared to GelB.
•Dyes based on acceptor-phenyl-donor were designed and synthesized.•The highest photoluminescence quantum yield of coated dyes on the solid film was 33%.•The highest value for ionization potential ...from electron photoemission was found to be −5.45 eV.•The dyes were mechanochromic as they change color under the force of 0.5 GPa.
Considering the simple peripheral methoxy or/and tert‑butyl substitution at 3,6-position of carbazole and the phenyl ring as a bridge to increase the electron-donor property, emission colors of acceptor-phenyl-donor type (A-Ph-D) of dyes were designed. In this study, two dyes based on groups comprising 1-(9-bromoanthracene)-4-(3‑methoxy-9H-carbazole-9-ylphenyl and 1-(9-bromoanthracene)-4-(3,6-di‑tert‑butyl‑9H-carba-zole-9-ylphenyl were synthesized. The density functional theory (DFT) was evaluated and the separate distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) was observed. Besides, the photophysical properties of dyes showed the maximum absorption spectra (ABS) at 295 and 299 nm for the spin-coated dyes on the solid film. The photoluminescence spectra (PL) for the emitters revealed the blue and cyan light hues. Additionally, the mechanochromic characteristics, aggregation-induced emission enhancement (AIEE), and thermal stability were also investigated. Our approach resulted in coated dyes on the films with suitable values of ionization potential -5.31 and -5.45 eV in tandem. Moreover, the photoluminescence quantum yields (PLQYs) of the two spin-coated dyes are above 24 and 33%.
Display omitted
Two natural dyes containing anthocyanin are extracted from sour and sweet pomegranate from Iran. Spectrophotometric evaluation of the natural dyes in solution and on a TiO2 substrate was carried out ...to assess changes in the status of the natural dyes. The results show that the natural dyes indicate buthochromic shift on the TiO2 substrates. Dye-sensitized solar cells (DSSCs) are fabricated to determine the photovoltaic behaviour of each dye and the mixture of extracts. Such evaluations demonstrate conversion efficiencies of 0.73%, 1.57% and 0.91% for sour pomegranate, sweet pomegranate and mixed extract respectively. Natural dyes are suitable alternative photosensitizers for DSSCs.
Today, the issue of reducing industrial pollution has received much attention. The textile industry is of high important throughout the world. However, its by‐product wastewater pollutes the ...environment. The first approach was the selection of plant‐based dyes (madder and reseda) and the application of tannin‐based mordants (pomegranate peel and myrobalan). The extraction of madder, reseda, and pomegranate peel in water with the ultrasound‐assisted method was done. In this article, pre‐mordanting method was used for mordanting and Cu (copper) and alum were selected as the mineral mordant to compare the results. Fourier Transform Infrared Spectroscopy method was employed to analyze the obtained extracts and to investigate the changes in the fibers. The results showed that K/S (color strength) values of the dyed samples increased by increasing the dye concentration. The colorfastness properties of the samples were investigated according the ISO standards.
Two dyes containing of thioxanthenone derivative as an acceptor unit, were designed and synthesized for thermally activated delayed fluorescence (TADF) organic light emitting diodes (OLEDs). The ...photoluminescence (PL) spectra of hammered dyes were shifted and the dyes were mechanochromic. Ionization potential (IP) values of spin-coated dyes on the fluorine-tin oxide film ranged from −5.42 to −5.49 eV and the hole mobility values reached to 2.64 × 10−4 and 3.56 × 10−4 cm2 V−1s−1. Considering the higher values of the photoluminescence quantum yields (PLQYs) of spin-coated dyes on the solid films (16, 21%) that dispersed the dyes in a solution such as toluene (7, 3%), the aggregation induced emission enhancement (AIEE) phenomena were observed. In addition, the doped devices were fabricated based on 50 wt% poly (9,9-dioctylfluorene-alt-N-(4-sec-butylphenyl)-diphenylamine) (TFB) as a host material through the solution process and physically evaporation deposition (PVD). In this study, the effect of utilizing 4, 4′, 4″-Tris (3-methylphenyl) phenylaminotriphenylamine (m-MTDATA) as a hole transport layer was impressive and the exciplex forming was confirmed. Finally, the electroluminescence with CIE(x,y) of (0.2076,0.3634) was resulted for the device consisted of low turn on voltage of 4.43 V, maximum brightness of 21362.55 cd m−2, maximum current and power efficiency of 27.03 cd A−1 and 19.65 lm.W−1 and maximum external quantum efficiency of 9.71%.
Display omitted
•New type of TADF dyes based on thioxanthenone derivative are synthesized.•The emission color changes under hammering.•The highest values for ionization potential and hole mobility were found to −5.49 eV and 3.56 × 10−4 cm2.V−1s−1 respectively.•Doped devices were fabricated using TFB as a host.•The maximum external quantum efficiency was achieved to 9.71%.
Display omitted
•Novel naphthalimide sulfonylphenyl derivative was designed and synthesized as a host.•For the FL, PH and TTA mechanisms, decay lifetime increased with decreasing temperature.•For the ...TADF mechanism, the decay lifetime increased with increasing temperature.•Two values of slope were obtained for TTA mechanism when measuring power dependence.•The OLED with TADF emitter had the highest EQE compared to other OLEDs.
One of the biggest challenges in the field of optoelectronics is to easily identify the mechanisms involved in light-emitting materials. There are several different mechanisms of emission, and the best known are fluorescence (FL), phosphorescence (PH), thermally activated delayed fluorescence (TADF), and triplet–triplet annihilation (TTA). In this study, simple ways to diagnose these mechanisms are presented with an example. N,N-di(benzenesulfonylphenyl)-N-(N-2-aminomethylpyridine-1,8-naphthalimide)amine is synthesized as a host compound due to its high HOMO-LUMO and ionization potential (IP) values and three emitters consisting of 50 wt% Bis (1phenylisoquinoline))(acetylacetonate)iridium(III) (Ir(piq)2(acac)), 10-(4-(4,6-Diphenyl-1,3,5-triazin-2-yl)phenyl)-9,9-dimethyl-9,10-dihydroacridine (DMAC-TRZ) and 1,1′-(2,5-Dimethyl-1,4-phenylene)dipyrene (DMPPP) were considered. Overall, the host compound, doped Ir(piq)2(acac) and doped DMPPP follow the mechanisms of FL, the combination of FL and PH, and the combination of FL and TTA, as the photoluminescence (PL) decay life time and the PL intensity increased with decreasing temperature. However, DMAC-TRZ doped with the host compound showed the TADF mechanism, as the PL decay lifetime and the PL intensity increase simultaneously with increasing temperature. In addition, the difference between the singlet excited state (S1) and the triplet excited state T1 (ΔEST) from the PL and PH spectra at 77 K for the spin-coated DMAC-TRZ-doped host show the lowest value in between the samples at 0.02 eV, and the reverse intersystem crossing (rISC) effect is activated. Moreover, the linear slopes of the power dependence analysis of the DMPPP-doped host were calculated to be 2.04 and 0.91, indicating that there are two components (photons) for this sample which is strong evidence for the TTA mechanism. Taking into account the synthesized host compound, (Ir(piq)2(acac):host), (DMAC-TRZ:host) and (DMPPP:host) as emitter layers, the organic light emitting diodes (OLEDs) were fabricated via solution processing, and the TADF OLED exhibited the highest efficiency among the other OLEDs.
Today, reducing industrial pollution and using agricultural waste has become very important in preserving the environment and increasing productivity. The textile industry has a high level of ...pollution caused by wastewater containing dyes, and the use of natural dyes can overcome this weakness. To increase color strength, it is customary to use a mordant. The use of natural mordant can help to complete the sustainable cycle of the dyeing process. In This study extracts of madder and Oleaster or Russian Olive were utilized as natural dye and mordant, respectively. The phenolic content of Oleaster and its components (peel, seed, and flesh) were investigated and the results illustrated that the components of Oleaster, especially the peel and seeds, can be used as natural mordant as agricultural waste. The Fourier transform infrared spectral behavior of mordanted yarns were similar, which indicates the similar performance of different components of Oleaster. The color strength was studied in the presence of different mordants, and the results showed that the use of different components of the Oleaster can improve the color strength. Moreover, the dyed yarns were subjected to stability evaluations using standard methods. Washing, rubbing and light fastness of dyed yarns using mordant were good, good and moderate, respectively.
Graphical abstract
In this paper, a novel nanocrystalline composite material of hydroxyapatite (HA)/polyvinyltrimethoxysilane (PVTMS)/iron(II)chloride tetrahydrate (Clsub.2FeHsub.8-Osub.4) with hexagonal structure is ...proposed for the fabrication of a gas/temperature sensor. Taking into account the sensitivity of HA to high temperatures, to prevent the collapse and breakdown of bonds and the leakage of volatiles without damaging the composite structure, a freeze-drying machine is designed and fabricated. X-ray diffraction, FTIR, SEM, EDAX, TEM, absorption and photoluminescence analyses of composite are studied. XRD is used to confirm the material structure and the crystallite size of the composite is calculated by the Monshi-Scherrer method, and a value of 81.60 ± 0.06 nm is obtained. The influence of the oxygen environment on the absorption and photoluminescence measurements of the composite and the influence of vaporized ethanol, Nsub.2 and CO on the SiOsub.2/composite/Ag sensor device are investigated. The sensor with a 30 nm-thick layer of composite shows the highest response to vaporized ethanol, Nsub.2 and ambient CO. Overall, the composite and sensor exhibit a good selectivity to oxygen, vaporized ethanol, Nsub.2 and CO environments.
Display omitted
•Some new fluorescent azo-pyrazole-sulfonamide hybrids have been synthesized.•According to the values of universal index of electrophilicity (ω), the dye 5d has the highest ω.•The ...values of ionization potential from photoelectron emission spectrometry are in the range from 5.58 to 6.07 eV.•The highest photocurrent is obtained for individual DSSC based on dye with –NO2 group.
In this study, we have designed and investigated four new low-emitting fluorescent dyes consisting of sulfonamide derivatives with substitution groups in the LUMO moiety. In these dyes, sulfonamide linked with pyrazole group played an important role in complementing the acceptor moieties. The optical properties of dyes were evaluated by the UV–VIS absorption, photoluminescence spectroscopy and photoluminescence decay time analysis in the non-doped solid film. The strong effect of substitution by –NO2 group was impressive, when, the dyes ionization potential photon energy values reached to 5.58, 5.82, 5.83 and 6.07 eV. According to X-ray diffraction, dyes were not amorphous and value of crystallite size was ∼100 nm. The dyes have a promising application as a hole layer in dye sensitized solar cells (DSSCs), due to the separation distribution of HOMO-LUMO, thermal stability, small crystal size, high PLQY, high optical band gap and high electron affinity. Finally, the DSSCs devices were fabricated based on the synthesized dyes and the results showed that the efficiency of the DSSCs based on a dye with –NO2 group is higher (3.27%) than that of the other dyes.
Purpose
– The purpose of this paper is to prepare new organic dyes and use them as sensitisers in dye-sensitised solar cells. These dyes were synthesised and purified and then characterised by ...analytical techniques. Spectrophotometric evaluations of the prepared dyes were carried out in solution and on a nano-anatase TiO2 substrate to assess the possible changes in the status of the dyes in different environments. Finally, the photovoltaic properties were investigated in dye-sensitised solar cells.
Design/methodology/approach
– So as to synthesise dyes, N-substituents carbazole were utilised as the fundamental electron donor group and cyanoacrylic acid or acrylic acid as electron acceptor anchoring groups. Purified dyes were dissolved in solution and coated on TiO2 substrate. Finally, dye-sensitised solar cells were fabricated to determine the photovoltaic behaviour and conversion efficiency of each individual dye.
Findings
– The results showed that the dyes form j-type aggregates on the nano TiO2. The oxidation potential of synthesised carbazole dyes is
>
0.2 V vs Fc/Fc+; hence, their high performance in dye-sensitised solar cells. Dye 3 exhibited 2.11 per cent of conversion efficiency in comparison to 2.89 per cent for the identical cells with Dye 9 containing cyanoacrylic acid which acted as the best acceptor group.
Practical implications
– The novel dyes look as promising as highly light fast, efficient dyes for dye-sensitised solar cells.
Social implications
– Organic dye provides low cost and less hazardous materials for dye-sensitised solar cells.
Originality/value
– A series of new organic dyes were synthesised as sensitisers for dye-sensitised solar cells for the first time.
