Seven aromatic hydrocarbons bearing a dicyanovinyl unit were prepared to determine the relationship between both the number of a omatic rings and location of acceptor substituent on their thermal and optoelectronic pro pe ties. Additionally, the density functional theory calculations were performed. The obtained co mpounds showed temperatures of the beginning of thermal decomposition in the range of 137 – 289 °C, being above their respective melting points found between 88 and 248 °C. They were electrochemically active and showed quasi-reversible reduction process (except for 2-(phen-1 yl)methylene)malononitrile). Electrochemically esti mated energy band gaps were below 3.0 eV, in the range of 2.10 – 2.50 eV. The absorption and emission spectra were recorded in CHCl3 and NMP and in solid state. All compounds strongly absorbed radiation with absorption maximum ranging from 307 to 454 nm ascri bed to the intramolecular charge transfer between the donor and acceptor units. The aromatic hydrocarbons were luminescent in all investigated media and exhibited higher phot oluminescence quantum yields in the solid state due to the aggregation induced emission pheno m a. Electroluminescence ability of selected compounds was tested in a diode with guest -host configuration. Additionally, the selected compound together with a commercial N719 w as applied in the dye-sensitized solar cell.

Seven aromatic hydrocarbons bearing a dicyanovinyl unit were prepared to determine the relationship between both the number of aromatic rings and location of acceptor substituent on their thermal and optoelectronic properties. Additionally, the density functional theory calculations were performed. The obtained compounds showed temperatures of the beginning of thermal decomposition in the range of 137-289 degrees C, being above their respective melting points found between 88 and 248 degrees C. They were electrochemically active and showed quasi-reversible reduction process (except for 2-(phen-l-yl)methylene)malononitrile). Electrochemically estimated energy band gaps were below 3.0 eV, in the range of 2.10-2.50 eV. The absorption and emission spectra were recorded in CHCl3 and NMP and in solid state. All compounds strongly absorbed radiation with absorption maximum ranging from 307 to 454 nm ascribed to the intramolecular charge transfer between the donor and acceptor units. The aromatic hydrocarbons were luminescent in all investigated media and exhibited higher photoluminescence quantum yields in the solid state due to the aggregation induced emission phenomena. Electroluminescence ability of selected compounds was tested in a diode with guest-host configuration. Additionally, the selected compound together with a commercial N719 was applied in the dye-sensitized solar cell.

Three push-pull molecules with linear, quadrupolar and tripodal arrangements, consisting of triphenylamine (electro-donor) substituted with malononitrile groups (electro-acceptor), were synthesized with high yield by a simple procedure. Impact of the number of malononitrile substituents on optoelectronic properties was investigated with cyclic voltammetry, absorption and emission spectroscopy, as well as density functional theory calculation. The derivatives formed amorphous materials and exhibited low energy band gaps ranging from 2.06 to 2.49 eV. UV-Vis absorption and photoluminescence emission spectra were investigated in solutions (CHCI3, NMP) and in solid-state as thin films and two kinds of blends (with PMMA and PVK:PBD). Quantum yield of photoluminescence was dependent on the molecule structure, solvent, and solid-state layer formulation. The compounds exhibited high photoluminescence quantum yield in the range of 15-42% and 12-59% in solid-state as film and blend with PMMA (1 wt%), respectively, being promising for applications in light emitting diodes. The diodes with active layer consisting of neat derivatives and compounds molecularly dispersed in PVK:PBD (50:50 wt%) matrix showed orange and green electroluminescence. (C) 2018 Elsevier B.V. All tights reserved.

A series of imines based on tris(2-aminoethyl)amine was designed and synthesized to evaluate the effect of core functionalization with biphenyl, pyrene, anthracene, triphenylamine and phenanthrene units on selected properties. Their chemical structure was thoroughly characterized by NMR and FTIR spectroscopy and elemental analysis. All compounds were crystalline (except for imine with triphenylamine units) and melted in the wide temperature range of 99-187 degrees C, according to the structure of the substituent. DSC measurements revealed that the studied compounds can be converted into amorphous material with glass transition occurring for temperatures between 16 and 55 degrees C. The imines were electrochemically active and underwent oxidation and reduction processes as found using CV and DPV methods. Density functional theory was employed for optimizing the imines geometry, as well as for calculating HOMO and LUMO orbital energies together with ionization potentials and electron affinities. The absorption and photoluminescence in the UV-Vis spectral range, both in solution and in the solid state as films on glass substrates were studied. When dissolved in chloroform, they emitted light with quantum yields ranging from 0.54 to 22%. In the solid state they exhibited emission in the range of 380-515 nm. The selected compounds were preliminarily tested as components in light emitting diodes. The ability neat azomethines for electroluminescence in diode ITO/PEDOT:PSS/imine/Al was demonstrated.

A series of molecules with a dicyanovinyl acceptor connected with various substituted phenyls as donor blocks were synthesized and characterized. The thermal, electrochemical and photophysical properties of these compounds were investigated and compared. DSC and TGA measurements revealed that all compounds showed high both different melting transitions and the beginning of decomposition. The electrochemical studies did not show significant differences in energy band gap being between 2.41 and 2.55 eV (except for one with carbazole unit), which was also supported by the density functional theory calculations. They emitted light with higher photoluminescence quantum yield in film than in solution. Blends containing the malononitrile derivatives dispersed in a solid matrix consisting of poly(9-vinylcarbazole) and (2-tert-butylpheny1-5-biphenyl-1,3,4-oxadiazole) emitted with small or high contribution from the host, signaling efficient or incomplete energy transfer from host to guest molecules. Emission of light under external voltage by diodes based on these blends was observed.

Six novel azomethines with substituted thiophene central core were synthesized and their properties are reported. They were obtained by the condensation reaction between 2,5-diamino-thiophene-3,4-dicarboxylic acid diethyl ester and various aldehydes. The imines were characterized by NMR and FTIR spectroscopies and by elemental analysis. DSC measurements revealed that the prepared compounds are molecular glasses (except for one) with high Tg varying from 94 and 183°C. Their redox properties were investigated in solution by cyclic voltammetry and differential pulse voltammetry. It was found that all imines were electrochemically active and showed low values of energy band gap ranging from 1.61 to 1.78eV. Photoluminescence measurements indicated that they emitted light in solution with quantum yield (ΦPL) in the range of 1.2–14.3% and in solid state as film and blend with poly(methyl methacrylate) and binary blend with poly(9-vinylcarbazole) (PVK) and (2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole) (PDB) with ΦPL form 0.24–1.77% and from 0.52% to 1.66%, respectively. The density functional theory (DFT) was applied for calculating their geometries and frontier molecular orbitals. Their electroluminescence ability was examined in guest-host diode with structure ITO/PEDOT:PSS/PVK:PBD:imine/Al and emission of light with maximum of emission band from 626 to 674nm was observed. This work demonstrates, to the best of our knowledge, the first example of light emitting devices based on thiophene azomethines as active layer component.

A series of polyaromatic hydrocarbons with anthracene, phenanthrene and pyrene units connected with Schiff base junctions were synthesized via condensation of p-phenylenediamine and hydrazine with selected aldehydes. The effect of both hydrocarbon structures and presence of N-N- or phenyl- linked diimines on properties of the prepared azines and azomethines was analyzed. The obtained compounds were soluble in common organic solvents and melted in the range of 226–317°C. Their photophysical and electrochemical properties were investigated by UV–vis, photoluminescence spectroscopies and cyclic voltammetry (CV), respectively. Moreover, a density functional theory (DFT) was applied for calculation of their electronic and geometric structures as well as absorption and emission spectra. Additionally, their electron acceptor activity was preliminary tested in photovoltaic experiment.

The new Schiff bases bearing anthracene unit were synthesized from 2-aminoanthracene and various aldehydes such as: benzaldehyde, 4-(diphenylamino)benzaldehyde, 9-phenanthrenecarboxaldehyde, 9-anthracenecarboxaldehyde, and biphenyl-4-carboxaldehyde, 2-naphthaldehyde. Resulted azomethines were characterized by IR, NMR (1H and 13C), elemental analysis and UV–vis spectroscopy. The imine consists of anthracene and biphenyl moieties exhibited liquid crystal properties and their nematic phase showed Schlieren texture. The photoluminescence measurements carried out in solution and in solid state as blend with PMMA revealed the ability of the imines to emission of the blue light with quantum yield efficiency in the range of 2.18–6.03% in blend. Based on the electrochemical experiment they showed value of energy gap (Eg) in the range of 2.5–2.7eV. Additionally, density functional theory (DFT) was applied for calculations of both electronic structure and spectroscopic properties of synthesized Schiff bases. Moreover, the results obtained from preliminary tests of application of the azomethines in organic photovoltaic (OPV) devices confirmed their electron acceptor character.

A series of novel Schiff bases via condensation reaction of 2-naphtylamine with benzaldehyde, terephthalaldehyde, 9-anthracenecarboxaldehyde, 9-phenantrenecarboxaldehyde, 2-naphthaldehyde and biphenyl-4-carboxaldehyde was synthesized and examined. In the most cases the prepared compounds exhibited the temperature of 5% weight loss about 270 degrees C. Resulting imines exhibited similar photoluminescence properties and emitted blue light in its blends with PMMA with quantum yield efficiency in the range of 1.98-9.69%.The highest luminescence intensity exhibited Schiff bases consisting of two naphthalene units. Electrochemical measurements (CV and DPC) revealed, in the most cases, two reversible reduction and irreversible oxidation processes. They showed a low value of electrochemically calculated energy gap (E-g) about 1.6 eV. Additionally, the electronic properties, that is, orbital energies and resulting energy gap were calculated theoretically by density functional theory (DFT). Considering the obtained results it seems that the prepared imines can be interesting for optoelectronic applications. The reversible reduction and low E-g suggest that they can be treated as acceptors. Thus, the activity of selected compound was tested in photovoltaic solar cell with the following architecture ITO/PEDOT:PSS/P3HT or P3OT:imine/AI under illumination 1.3 mW/cm(2). The highest conversion efficiency was 0.32%, which confirmed its electron acceptor character. (C) 2015 Elsevier B.V. All rights reserved.

The unsymmetrical and symmetrical azines prepared by condensation of benzophenone hydrazone with (di)aldehydes with thiophene rings were reported in this study The structures of obtained compounds were characterized by FTIR, H-1 NMR, and C-13 NMR spectroscopy as well as elemental analysis. Optical, electrochemical, and thermal properties of azines were investigated. The unsymmetrical azine with bithiophene unit exhibited liquid crystalline properties as was detected by DSC and POM experiments. All compounds are electrochemically active, however, only azines with bithiophene structure undergo reversible reduction process as was found in cyclic and differential pulse voltammetry (CV and DPV) studies. Additionally, the electronic properties, that is, orbital energies and resulting energy gap were calculated theoretically by density functional theory (DFT). The photovoltaic properties of two azines as active layer in organic solar cells at the configuration ITO/PEDOT:PSS/active layer/Al under an illumination of 1.3 mW/cm(2) were studied. Active cell layers blends of poly 3-hekxylthiophene (P3HT) or poly 3-butylthiophene (P3OT) with azines were applied. The device comprising P3HT with symmetrical azine containing bithiophene unit showed the highest value of power conversion efficiency (0.82%). To the best of our knowledge, the azines are very seldom considered as potential compounds in active layer in bulk heterojunction (BHJ) solar cells. (C) 2014 Elsevier B.V. All rights reserved.

The azines being condensation products of benzophenone hydrazone with triphenylamine substituted with different numbers of aldehyde groups and also with terephthaldicarboxaldehyde were prepared. Their spectral, thermal and electronic properties that is, orbital energies and resulting energy gap calculated theoretically by density functional theory (DFT) and estimated by electrochemical measurements were explored. The prepared hydrazine derivatives exhibited glass-forming properties with glass-transition temperatures in the range of 10-98 degrees C and high thermal stability with decomposition temperatures placed between 231 and 337 degrees C. The photoluminescence (PL) studies showed that all investigated compounds both in solid state as blends with PMMA and in NMP solution emitted blue light, however, with different intensity. Relative PL intensity of azines was investigated in NMP in relation to rhodamine-B used as a standard. Moreover, the stability of azines during doping with acid and ferric chloride was spectroscopically demonstrated via repeated dopingidedoping in solution and in film. All compounds are electrochemically active. Depend on chemical structure of azines they undergo reversible or irreversible electrochemical oxidation and reduction processes. The LUMO levels were found in the range from -2.66 to -3.0 eV. They exhibited energy band gap (E-g) estimated electrochemically from 2.57 to 3.22 eV. (C) 2014 Elsevier B.V. All rights reserved.

Two series of azines and their azomethine analogues were prepared via condensation reaction of benzaldehyde, 2-hydroxybenzaldehyde, 4-pyridinecarboxaldehyde, 2-thiophenecarboxaldehyde, and 4-(diphenylamino)benzaldehyde with hydrazine monohydrate and 1,4-phenylenediamine, respectively. The structures of given compounds were characterized by FTIR, (1)H NMR, and (13)C NMR spectroscopy as well as elemental analysis. Optical, electrochemical, and thermal properties of all compounds were investigated by means of differential scanning calorimetry (DSC), UV-vis spectroscopy, stationary and time-resolved photoluminescence spectroscopy, and cycling voltammetry (CV). Additionally, the electronic properties, that is, orbital energies and resulting energy gap were calculated theoretically by density functional theory (DFT). Influence of chemical structure of the compounds on their properties was analyzed.

Polyazomethine (OFBF-TPA) based on triphenylamine (TPA) and octafluorobiphenyl (OFBF) moieties was tested as donor–acceptor (D-A) for bulk heterojunction polymeric solar cells. The temperatures of 5% weight loss ( T5%) of the polyazomethine range from 323 to 328°C, depending on the gas used (air and nitrogen). The conductivity of OFBF-TPA was approximately 10−10 S/cm for not annealed sample and at about 10−6 S/cm for the ones annealed at room temperature, as determined by impedance spectroscopy. Surface of the polymer and mixture polymer–[6,6]-phenyl C61 butyric acid methyl ester (PCBM) was smooth with the Rms value in the range 0.58–1.95 nm as was detected by the atomic force microscopy (AFM) technique. UV-vis spectrum of the mixture OFBF-TPA-PCBM exhibited higher absorption intensity than the UV-vis spectrum of OFBF-TPA lacking PCBM. The thin solid film of OFBF-TPA and OFBF-TPA-PCBM showed one main absorption band with a maximum peak at 414 and 411 nm, respectively. For the mixture OFBF-TPA-PCBM, the second absorption band at 333 nm was found. No influence of annealing on the absorption properties was observed. The polymer solar cell devices were fabricated by spin coating the blend solution of the OFBF-TPA and PCBM and investigated in dark and under an illumination of 100 mW/cm2, with an AM1.5 G. Electrical behavior of the device indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene) (PEDOT)- poly(styrenesulfonate) (PSS)/OFBF-TPA-PCBM/Al was tested by impedance spectroscopy in dark and under illumination. For all measured devices, Nyquist plots were presented. The annealing significantly improved the electrical conductivity of the investigated devices. Electrical and photovoltaic properties of OFBF-TPA were compared with the properties of polyazomethine based on TPA and fluorene moieties (F-TPA).

The molecules bearing triphenylamine (TPA) structure were widely investigated mainly as active hole-transporting materials for construction of light-emitting diodes. Our previous research was concerned for poly(azomethines) bearing TPA in structure. Now we present research of its model compounds. A series of five conjugated azomethines have been synthesized in reaction of different aromatic diamines and 4-formyltriphenylamine. The structures of given azomethines were characterized by means of FTIR, H-1 NMR, and C-13 NMR spectroscopy and elemental analysis. Optical, electrochemical and thermal properties of all compounds were investigated by means of differential scanning calorimetry (DSC), UV-vis spectroscopy, photoluminescence spectroscopy and cycling voltammetry. Influence of chemical structure of the compounds on their properties has been analyzed. (C) 2012 Elsevier B.V. All rights reserved.

Spectroscopic and photophysical properties of the poly(azomethine)s with triphenylamine moieties were investigated by UV-vis, X-ray diffraction and atomic force microscopy methods. Current voltage measurements were performed on ITO/polymer/Alq(3)/Al, ITO/PEDOT/polymer:MWCNT/Al and ITO/polymer:MWCNT/Al devices. Multiwall carbon nanotubes were blended with polymer in the ratio 1:1. The lowest optical band gap value at 2.33 eV was detected. Moreover, an absorption coefficient alpha was calculated from transmission and reflectivity measurements. In this paper, we presented photophysical and structural properties of the poly(azomethine)s in solid state of great interest for the emerging field of molecular electronics and for their uses as active layers in (opto)electronic devices such as solar cells.

New, solution processable azomethines, consisting of electron-donating triarylamine units (TPA) were synthesised via condensation of 4-formyltriphenylamine with 1,5-diaminonaphthalene, 1,4-diaminonaphthalene, 3,3'-dimethylnaphtidine and 3,8-diamino-6-phenylphenanthridine in view of their potential application in organic (opto)electronics. The structures of the compounds were characterized by means of IR, NMR spectroscopy and elemental analysis; the results show an agreement with the proposed structure. The prepared azomethines exhibited glass-forming properties with glass-transition temperatures in the range of 102-222 degrees C. Optical properties of the prepared compounds were investigated by UV-Vis and photoluminescence (PL) measurements. The obtained compounds emitted blue-green light in chloroform solution with emission maximum (lambda(em)) at ca. 500 nm and blue one (lambda(em) similar to 440 nm) in blend with PMMA. The electrochemical behavior of azomethines was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The HOMO level was in the range from -5.08 to -5.22 eV. The HOMO, LUMO levels and energy band gap (E-g) were additionally calculated theoretically at B3LYP/6-31G(d,p) level.It was found that imine obtained from 1,4-diaminonaphthalene exhibited better conjugation than other TPA-based azomethines. Preliminary electrical conductivity measurements were carried out on ITO/compound/Al devices. (C) 2012 Elsevier B.V. All rights reserved.

Low molecular weight compounds and polymers consisting of 1 and 2 thiophenes and double azomethine bonds prepared from hydrazine and thiophene aldehydes are presented. The effect of the number of thiophene rings on thermal, optical and electrochemical properties was examined. Polyazine with bithiophene structure exhibited slightly higher both glass transition temperature (T-g = 121 degrees C) and the decomposition temperature (T-10 = 345 degrees C) than polymer with one thiophene ring in repeating unit (T-g = 115 degrees C, T-10 = 321 degrees C). A higher degree of conjugation due to presence of bithiophene structure was confirmed by bathochromic shift of the absorbance and photoluminescence. Doping with HCl and FeCl3 resulted in increase of fluorescence intensity. All the obtained compounds emitted blue light with the highest intensity both in solution and in solid state as a blend with PMMA. The investigated compounds exhibited electrochemical energy gap (E-g) in the range of 1.94-3.07 eV. Introduction of a second thiophene ring resulted in a decrease of E-g by about 0.9 eV in the case of azines and 0.67 eV in polyazines. Additionally, energy band gap (E-g) was calculated theoretically at B3LYP/6-31G(d,p) level of theory. (C) 2012 Elsevier B.V. All rights reserved.

Two novel poly(azomethinenaphthaleneimide)s (poly(AZ-NI)s) and azomethine-naphthalene diimide (AZ-NI) consisting of electron-donating triarylamine with imine linkages and electron-accepting naphthalene diimide moieties were prepared via condensation of N,N'-bis(4-amino-2,3,5,6-tetramethylphenyl)naphthalene-1,4,5,8-dicarboxyimide (DANDI) with 4-formyltriphenylamine, 4,4'-diformyltriphenylamine and 4.4',4"-triformyltriphenylamine. The thermal degradation kinetics of obtained compounds was studied by TGA. The activation energy (E-a) of thermal decomposition process was estimated by the first order Coats-Redfern equation and was in the range 115.1-266.7 kJ/mol. Poly(AZ-NI)s and AZ-NI exhibited useful levels of thermal stability, their 5% weight-loss temperatures were above 350 degrees C. Optical properties of the prepared compounds were investigated by UV-vis and photoluminescence (PL) measurements. The obtained alternating donor-acceptor compounds emitted mainly blue light. The electrochemical behavior of poly(AZ-NI)s, AZ-NI and DANDI was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). As calculated from CV, the electrochemical energy band gap (E-g) of the linear polymer was equal to 1.15 eV, but the E-g of the branched one was lower: 1.06 eV, whereas the E-g of AZ-NI and DANDI was 1.32 and 0.47 eV, respectively. For the first time, to the best of our knowledge, polynaphthaleneimides with triphenylamine units and azomethine linkages have been described in this article. C) 2011 Elsevier B.V. All rights reserved.

Organic hole-transporting materials are intensively investigated as thin-layer electro-optical devices, including organic light-emitting diodes, solar cells, organic field-effect transistors and photo-refractive holographic materials. In this review, we discuss synthetic routes and optical (UV–vis, PL, CV) and electrical (I–V, EL, hole drift mobility) properties of polymers with triphenylamine (TPA) units in the main chain or as pendant groups, such as poly(vinylene)s, poly(amide)s, poly(imide)s, poly(azomethine)s, poly(arylate)s, poly(urethane)s and poly(ester)s. The introduction of vinyl, acetylene, ester, imide, amide or azomethine moieties in TPA leads to new functional materials based on their synergistic effects. The introduction of bulky triphenylamine in macromolecules tends to suppress intermolecular aggregation, reduce the crystallisation propensity and improve the hole-transporting ability of the materials.