Otrzymanie i badania fizykochemiczne związków z układami wiązań π-sprzężonych projektowanych do potencjalnych zastosowań w organicznej elektronice

The aim of the doctoral thesis was to obtain low molecular weight compounds with systems of n-conjugated bonds and examine the relationship between their chemical structure and selected physical properties important from the point of view of a potential application in organic optoelectronics. In the frame of work, 57 compounds were obtained and investigated. They can be divided into three groups, namely derivatives of malononitrile, azomethines, and azometineimides. To study thermal properties of the synthesized compounds, that is, thermal stability and temperature of phase transitions and glass transition temperature, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were applied, respectively. Absorption and photoluminescence properties (PL) in the UV-Vis range were investigated in solution and solid state in the form of films and blends (with PMMA and/or with PVK and/or with PVK: PBD). Cyclic voltammetry (CV) was used to estimate the ionization and electron affinity potentials and the energy band gap. Compounds with appropriate properties were selected to verify their electroluminescence (EL) capability in light emitting diodes (OLED), where they acted as the emission layer or its component. In this Ph.D. work, for the first time, the electroluminescence of azomethines (with the structure of thiophene and fluorene and with the N-phenylpyrrolidine substituent) and azomethineimides (containing a derivative of carbazole, benzoindole, phenanthrene) was demonstrated. It was found that increase of malononitrile derivative with triphenylamine and four CN groups and azomethineimides with phenanthrene and biphenyl, content from 2 to 15 wt. % in the PVK: PBD matrix raises the intensity of EL. Moreover, in the case of azomethineimides also change of color of the light emitted by the diode was observed. Some of the azomethines tested exhibited photoluminescence from the S2 singlet state, which has not been described so far in the literature for this group of compounds. In summary, taking into account the EL properties of the tested compounds, the attention should be paid on the malononitrile derivatives containing carbazole and triphenylamine structure, azomethines with fluorene and two N-phenylpyrrolidine groups and azomethineimides bearing a carbazole, triphenylamine, phenanthrene and biphenyl derivative, which seems to be the most promising for further application investigations. The investigations conducted within the framework of the Ph.D. thesis are basic research and contribute to a significant extension of knowledge concerning the selected types of compounds. The carried out research let to evaluate synthesized compounds ability for potential applications. Moreover, the found dependencies may help to design new materials with appropriate properties for applications in organic optoelectronics

Symmetrical and unsymmetrical azomethines with thiophene core : structure - properties investigations

Unsymmetrical and symmetrical azomethines were obtained using the condensation reaction of diamino-thiophene-3,4 dicarboxylic acid diethyl ester with 4-(1-pyrrolidino)benzaldehyde, fluorene-2-carboxaldehyde, 1-methylindole-3-carboxaldehyde, and benzothiazole-2-carboxaldehyde. Their thermal, optical, and electrochemical properties were investigated, and the results were supported by calculations using the density functional theory. The studied compounds melted in the range of 170–260 °C and can be converted into amorphous materials with high glass transition temperatures between 76 and 135 °C. They were thermally stable up to 220–300 °C. All imines were electrochemically active and exhibited low energy band gaps below 2 eV (except for one imine with Eg = 2.39 eV) determined on the basis of cyclic voltammetry. Most of the azomethines were emissive in solution and in the solid state. Some of them showed both S1 (first excited state) emission and S2 (second excited state) emission or only fluorescence from higher excited state, which is first time observed for azomethines. The imine with the most promising properties was tested in a light-emitting diode, and its ability for emission of light under external voltage was demonstrated

Photoelectrochemical and thermal characterization of aromatic hydrocarbons substituted with a dicyanovinyl unit

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 °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 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

New thiophene imines acting as hole transporting materials in photovoltaic devices

ASAP Article - Articles ASAP (as soon as publishable) are posted online and available to view immediately after technical editing, formatting for publication, and author proofing.Five new unsymmetric thiophene imines end-capped with an electron-donating amine (−NH2) group were obtained using a simple synthetic route, that is, the melt condensation of 2,5-diamino-thiophene-3,4-dicarboxylic acid diethyl ester with commercially available aldehydes. Their thermal stability and electrochemical and photophysical (absorption (UV−vis) and photoluminescence (PL)) properties were examined and density functional theory calculations were performed. The imines were thermally stable above 200 °C. They underwent reduction and oxidation processes and exhibited an energy band gap electrochemically estimated between 1.81 and 2.44 eV. They absorbed radiation from the UV and visible range to 480 nm and showed weak light emission. These compounds were investigated as hole transporting materials in solar cells with the structure FTO/b-TiO2/m-TiO2/perovskite/imine/Au. The highest photoelectric conversion efficiency was observed for compounds with a morpholine derivative substituent

Luminescence and electrochemical activity of new unsymmetrical 3- imino-1,8-naphthalimide derivatives

A new series of 1,8-naphtalimides containing an imine bond at the 3-position of the naphthalene ring was synthesized using 1H, 13C NMR, FTIR, and elementary analysis. The impact of the substituent in the imine linkage on the selected properties and bioimaging of the synthesized compounds was studied. They showed a melting temperature in the range of 120–164 C and underwent thermal decomposition above 280 C. Based on cyclic and differential pulse voltammetry, the electrochemical behavior of 1,8-naphtalimide derivatives was evaluated. The electrochemical reduction and oxidation processes were observed. The compounds were characterized by a low energy band gap (below 2.60 eV). Their photoluminescence activities were investigated in solution considering the solvent effect, in the aggregated and thin film, and a mixture of poly(N-vinylcarbazole) (PVK) and 2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole (PBD) (50:50 wt.%). They demonstrated low emissions due to photoinduced electron transport (PET) occurring in the solution and aggregation, which caused photoluminescence quenching. Some of them exhibited light emission as thin films. They emitted light in the range of 495 to 535 nm, with photoluminescence quantum yield at 4%. Despite the significant overlapping of its absorption range with emission of the PVK:PBD, incomplete Förster energy transfer from the matrix to the luminophore was found. Moreover, its luminescence ability induced by external voltage was tested in the diode with guest–host configuration. The possibility of compound hydrolysis due to the presence of the imine bond was also discussed, which could be of importance in biological studies that evaluate 3-imino-1,8-naphatalimides as imaging tools and fluorescent materials for diagnostic applications and molecular bioimaging

1,8-Naphthalimides 3-substituted with imine or β-ketoenamine unit evaluated as compounds for organic electronics and cell imaging

In this paper, we describe both new as well as described in our previous works 1,8- naphthalimide derivatives substituted at the 3-C position with imine or -ketoenamine unitin order to demonstrate a broader scope of research enabling of analysis between the structureproperties relationship relevant to the application of these compounds in organic electronics and cellular imaging. Thermal, physicochemical, optical, electrochemical, electroluminescence, and biological properties of a series of derivatives containing the 1,8-naphthalimideunit were tested and compared. This allowed the determination of impact of substituents in the imide part (hexylamine, phenylethyl, benzyl, fluorobenzyl, methylbenzyl), type of bond (imine or ketoenamine) as well as the substituent on the naphthalene ring (2-hydroxyphenyl, 5-bromo-2- hydroxyphenyl, 3,5-diodo-2-hydroxyphenyl, pyrimidines) on their properties. Moreover, the properties in the aggregating state were tested in the MeOH/PBS system. Imines are susceptible to the hydrolysis process and aggregation-caused photoluminescence quenching(ACQ). In turn,-ketoenamine shown excited-state intramolecular proton transfer promoted by aggregation (AIEE). Our studies can be helpful in the further design of compounds containing the 1,8- naphthalimide structure for various applications

New acceptor-donor-acceptor systems based on bis-(imino-1,8- naphthalimide)

In this paper, six novel symmetrical bis-(imino-1,8-naphthalimides) differing in core and N-substituent structure were synthesized, and their thermal (TGA, DSC), optical (UV-Vis, PL), electrochemical (DPV, CV) properties were evaluated. The compounds were stable to 280 C and could be transferred into amorphous materials. Electrochemical investigations showed their ability to occur reductions and oxidations processes. They exhibited deep LUMO levels of about -3.22 eV and HOMO levels above -5.80 eV. The optical investigations were carried out in the solutions (polar and non-polar) and in films and blends with PVK:PBD. Bis-(imino-1,8-naphthalimides) absorbed electromagnetic radiation in the range of 243–415 nm and emitted light from blue to yellow. Their capacity for light emission under voltage was preliminarily tested in devices with an active layer consisting of a neat compound and a blend with PVK:PBD. The diodes emitted green or red light

Ground- and excited-state properties of Re(I) carbonyl complexes - effect of triimine ligand core and appended heteroaromatic groups

In this work, a series of six rhenium(I) complexes bearing 2,2′ :6′ ,2′′ -terpyridine (terpy), 2,6-di(thiazol-2-yl)pyridine (dtpy), and 2,6-di(pyrazin-2-yl)pyridine (dppy) with appended quinolin-2-yl and N-ethylcarbazol-3-yl groups were prepared and spectroscopically investigated to evaluate the photophysical consequences of both the trisheterocyclic core (terpy, dtpy and dppy) and the heterocyclic substituent. The [ReCl(CO)3(Ln-κ2N)] complexes are regarded as ideal candidates for getting structure–property relationships, while terpy-like framework represents an excellent structural backbone for structural modifications. The replacement of the peripheral pyridine rings of 2,2′ :6′ ,2′′ -terpyridine by thiazoles and pyrazines resulted in a significant red-shift of the absorption and emission of [ReCl(CO)3(Ln-κ2N)] due to stabilization of the ligand-centred LUMO orbital. Both quinoline and Nethylcarbazole are extended π-conjugation organic chromophores, but they differ in electron-donating abilities. The low-energy absorption band of Re(I) complexes with the triimine ligands bearing quinolin-2-yl group was contributed by the metal-to-ligand charge-transfer (MLCT) electronic transitions. The introduction of electrondonating N-ethylcarbazol-3-yl substituent into the triimine acceptor core resulted in the change of the character of the HOMO of Re(I) complexes and a significant increase of molar absorption coefficients of the longwavelength absorption, which was assigned to a combination of 1MLCT and 1ILCT (intraligand chargetransfer) transitions. Regardless of the appended heteroaromatic group, the emitting excited state of Re(I) terpy-based complexes was demonstrated to have predominant 3MLCT character, as evidenced by comprehensive studies including static and time-resolved emission spectroscopy along with ultrafast transient absorption measurements. The diodes with Re(I) complexes dispersed molecularly in a PVK:PBD matrix were emissive andeffects of the complex structure on colour of emitted light and its intensity was pronounced

Synthesis and Thermal, Photophysical, Electrochemical Properties of 3,3-di[3-Arylcarbazol-9-ylmethyl]oxetane Derivatives

Novel oxetane-functionalized derivatives were synthesized to find the impact of carbazole substituents, such as 1-naphtyl, 9-ethylcarbazole and 4-(diphenylamino)phenyl, on their thermal, photophysical and electrochemical properties. Additionally, to obtain the optimized ground-state geometry and distribution of the frontier molecular orbital energy levels, density functional theory (DFT) calculations were used. Thermal investigations showed that the obtained compounds are highly thermally stable up to 360 C, as molecular glasses with glass transition temperatures in the range of 142–165 C. UV–Vis and photoluminescence studies were performed in solvents of differing in polarity, in the solid state as a thin film on glass substrate, and in powders, and were supported by DFT calculations. They emitted radiation both in solution and in film with photoluminescence quantum yield from 4% to 87%. Cyclic voltammetry measurements revealed that the materials undergo an oxidation process. Next, the synthesized molecules were tested as hole transporting materials (HTM) in perovskite solar cells with the structure FTO/b-TiO2/m-TiO2/perovskite/HTM/Au, and photovoltaic parameters were compared with the reference device without the oxetane derivatives

Symmetrical and asymmetrical imino-naphthalimides in perovskite solar cells

In perovskite solar cells, series of symmetrical and asymmetrical imino-naphthalimides were tested as hole-transporting materials. The compounds exhibited high thermal stability at the temperature of the beginning of thermal decomposition above 300 °C. Obtained imino-naphthalimides were electrochemically active and their adequate energy levels confirm the application possibility in the perovskite solar cells. Imino-naphthalimides were absorbed with the maximum wavelength in the range from 331 nm to 411 nm and emitted light from the blue spectral region in a chloroform solution. The presented materials were tested in the perovskite solar cells devices with a construction of FTO/b-TiO2/m-TiO2/perovskite/ HTM/Au. For comparison, the reference perovskite cells were also performed (without hole-transporting materials layer). Of all the proposed materials tested as hole-transporting materials, the bis-(imino-naphthalimide) containing in core the triphenylamine structure showed a power conversion efficiency at 1.10% with a short-circuit current at 1.86 mA and an open-circuit voltage at 581 mV