Jacek Ulanski

• Lodz University of Technology

In this study, it is shown that an efficient organic optocoupler (OPC) can be fabricated using commercially available and solution-processable organic semiconductors. The transmitter is a single-active-layer organic light-emitting diode (OLED) made from a well-known polyparavinylene derivative, Super Yellow. The receiver is an organic light-emittin...

The role of carboxylic, aldehyde, or epoxide groups incorporated into bottlebrush macromolecules as anchoring blocks (or cartilage-binding blocks) is investigated by measuring their lubricating properties and cartilage-binding effectiveness. Mica modified with amine groups is used to mimic the cartilage surface, while bottlebrush polymers functiona...

Our research shows that commercially available graphene on quartz modified with rhenium oxide meets the requirements for its use as a conductive and transparent anode in optoelectronic devices. The cluster growth of rhenium oxide enables an increase in the work function of graphene by 1.3 eV up to 5.2 eV, which guarantees an appropriate adjustment...

A method of producing an OLED, which consists in preparing a substrate with an indium-tin oxide anode layer, washing the substrate layer with an anode in organic solvents, applying an injection and transporting layer to the anode layer, made of a mixture of poly (3,4-ethylene-1, 4-dioxythiophene and sulphonated polystyrene by pouring onto a rotatin...

Our research shows that commercially available graphene on quartz modified with rhenium oxide meets the requirements for its use as a conductive and transparent anode in optoelectronic devices. The cluster growth of rhenium oxide enables an increase in the work function of graphene by 1.3 eV up to 5.2 eV, which guarantees an appropriate adjustment...

Core−shell nanocomposites comprising barium titanate, BaTiO3 (BTO), and poly(methyl methacrylate) (PMMA) chains grafted from its surface with varied grafting densities were prepared. BTO nanocrystals are high-k inorganic materials, and the obtained nanocomposites exhibit enhanced dielectric permittivity, as compared to neat PMMA, and a relatively l...

At this time, the development of advanced elastic dielectric materials for use in organic devices, particularly in organic field-effect transistors, is of considerable interest to the scientific community. In the present work, flexible poly(dimethylsiloxane) (PDMS) specimens cross-linked by means of ZnCl2-bipyridine coordination with an addition of...

In this work an unusual improvement in organic field effect transistor performance was explored after adding a very small amount (below 1 wt%) of hybrid nanoparticles containing TiO2 to poly(methyl...

Free-standing and flexible field-effect transistors based on 6,13-bis(triisopropylsilylethynyl)-pentacene (TIPS-pentacene)/polystyrene bilayers are obtained by well-controlled phase separation of both components. The phase separation is induced by solvent vapor annealing of initially amorphous blend films, leading to crystallization of TIPS-pentace...

The resonance Raman effect (RRE) is a phenomenon which results in a strong selective enhancement of Raman signals from the samples. Previous studies showed that the RRE in liquid water directly corresponds to its supramolecular structure. It was also reported that the electric-field-induced orientation of water molecules on the electrode surface re...

Spherical nano-objects composed of poly(acrylic acid-stat-acrylamide)-block-polystyrene (P(AA-stat-Am)-b-PS) were prepared via polymerization induced self-assembly (PISA) and used as templates for the synthesis of hybrid Ag@P(AA-stat-Am)-b-PS. These well-defined hybrids were used as effective surface-enhanced Raman spectroscopy (SERS) supports for...

Among solution-processable techniques, inkjet printing is a potential method for manufacturing low-cost and high-resolution polymer organic light-emitting diodes (PLEDs) for displays/solid-state lighting applications. Herein, we demonstrate use of the inkjet printed cesium carbonate (Cs2CO3) film as an electron injection interlayer. We have elabora...

Solution processable dielectric nanomaterials were prepared by the polymer-templated synthesis of the hybrid nanoparticles containing TiO2. Well defined poly(styrene-co-acrylonitrile)-b-poly(acrylic acid)-poly(divinylbenzene) (PSAN-b-PAA-PDVB) star-shaped copolymers were prepared by activators regenerated by electron transfer atom transfer radical...

In this work we study the influence of dielectric surface and process parameters on the geometry and electrical properties of silver electrodes obtained by electrohydrodynamic inkjet printing. The cross-section and thickness of printed silver tracks are optimized to achieve a high conductivity. Silver overprints with cross-section larger than 4 µm...

The possibility of efficient work function tuning of high‐quality graphene, grown on 6H‐SiC(0001), by covering it with thermally evaporated rhenium heptoxide (Re2O7) is presented. Raman spectroscopy, X‐ray photoelectron spectroscopy, and ultraviolet electron spectroscopy are used for structural, chemical, and electronic characterization of Re2O7/gr...

A series of new bis(benzo[h]quinolinato) Ir(III) complexes with modified β-ketoiminato ancillary ligands were synthesized, and their electrochemical, photophysical properties were determined with the support of theoretical calculations. Moreover, all the synthesized heteroleptic Ir(III) complexes were examined as dopants of the host–guest type emis...

The bulk heterojunction based created by poly(3-hexyltiophene-2,5-diyl) (P3HT phenyl-C61-butyric acid methyl ester (C60-PCBM) it is well-known system used in organic solar cells. As the performance of such solar cells are very sensitive to the processing conditions of the active layers, we have focused attention to preaggregation process of P3HT in...

In this work we analyse an influence of 80% ethoxylated polyethyleneimine (PEIE) interlayer modifying the ITO electrode work function on the detectivity and time response of the red-light sensitive photodetectors based on donor-acceptor copolymer HFQx-T (where HFQx stands for hexafluoroquinoxaline acceptor units, and T for benzodithiophene derivati...

Provides first-hand insights into advanced fabrication techniques for solution processable organic electronics materials and devices The field of printable organic electronics has emerged as a technology which plays a major role in materials science research and development. Printable organic electronics soon compete with, and for specific applica...

This study presents the inkjet printing of a novel OLED device with fully solution-processed organic layers that employ TADF material as an emitting layer. The ink was formulated using new TADF material, triazine core carbazole dendrimers with tert-butyl group at the periphery (tBuG2TAZ), dissolved in a mixture of two non-chlorinated solvents. The...

Inkjet printing technique allows manufacturing low cost organic light emitting diodes (OLEDs) in ambient conditions. The above approach enables upscaling of the OLEDs fabrication process which, as a result, would become faster than conventionally used vacuum based processing techniques. In this work, we use the inkjet printing technique to investig...

This chapter presents selected problems related to charge carrier transport in organic semiconductors, with a special emphasis on multicomponent materials, such as heavily doped semiconductors, composites, and nanocomposites. Fundamental concepts, terms, and models, commonly used in the description of both inorganic and organic semiconductors, are...

Charge-carrier transport in the channel of bottom gate, top contact organic field effect transistors with anisotropic layers of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-Pentacene) obtained by zone casting was investigated using scanning Kelvin probe microscopy combined with atomic force microscopy. The TIPS-Pentacene continuous layers con...

Non-fullerene acceptors based organic photovoltaics (OPVs) have attracted considerable attention in the last decade due to their great potential to realize high-power conversion efficiencies. To achieve higher performance OPVs, the fundamental challenges are in enabling efficient charge separation/transport and a low voltage loss at the same time....

A commercially available, soluble in chlorinated hydrocarbons perylene derivative, N,N-bis(1-ethylpropyl)-perylene-3,4:9,10-bis(dicarboximide) (PTCDI-C5(3)), was used to construct n-channel organic field effect transistors (OFETs). The transistors had the top-gate-bottom-contacts (TGBC) architecture, with a spin-coated layer of the active material....

Herein we report the investigation of non-doped exciplex formed in blends of 2,4,6-Tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T), working as the one-electron acceptor molecule, with different electron donors. The emission of these exciplexes spans from blue to orange-red, and shows clear contribution from thermally activated delayed fl...

This study presents the slot-die coating process of two layers of organic materials for the fabrication of organic light emitting diodes (OLEDs). Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), which is commonly used in OLEDs and in organic photovoltaic devices as the hole injection layer (HIL), has been deposited via slot-die c...

Two conjugated polymers, with different side chains of alkoxy substituted difluorobenzene and alkyl substituted difluorothiophene based on quinoxaline (Qx) as the electron acceptor unit and the benzodithiophene (BDT) as the electron donor unit, named HFQx-T and HFAQx-T, were used as electron donor polymers to fabricate all-polymer solar cells (all-...

CdTe/CdS core-shell quantum dots were synthesized and implemented into a light emitting device resulting in multi-channel electroluminescence with a light-green emission color. The main electroluminescence band at about 530 nm corresponds to the emission by the CdTe core (type I core/shell structure), while the next emission band at 595 nm is assig...

To provide high exciton utilization in organic light emitting diodes, phthalimide derivatives were designed and synthesized as exciplex-forming materials. Due to high triplet levels (2.92–3.11 eV) and ionization potentials (7.18–7.29 eV), the developed phthalimide derivatives were found to be not only appropriate accepting materials for the formati...

Poly(2-hydroxyethyl methacrylate) brushes were grown from a gold substrate by Atom Transfer Radical Polymerization (ATRP) and the material was applied as the gate dielectric layer in Organic Thin Film Transistor (OTFT) devices. The ATRP method provided 120 nm thick layers with relatively low roughness, as characterized by Atomic Force Microscopy. T...

We describe the synthesis and photodetecting properties of new, low band-gap copolymers: P1 with 5,6-difluoro-2,1,3-benzothiadiazole and P2 with 2,1,3-benzothiadiazole, both containing diketopyrrolopyrrole acceptor units. These compounds have been used for fabrication of single layer, solution processed photodetectors. For this purpose, two blends...

In this paper we report studies of the electronic structure as well as photophysical and emissive properties of family of new heteroleptic iridium(III) complexes of the general formula [Ir(bzq)2(N^O)] with...

Ambipolar organic field-effect transistors based on binary blends of n- and p-type semiconductors frequently suffer from low or unbalanced electron and hole transport. Uncontrolled phase separation and intermixing of donor and acceptor phases in such thin film blends lead to formation of bulk heterojunctions that lack sufficient percolation paths t...

This paper presents general information about ARUZ, a scalable, fully parallel data processing system equipped with low-latency communication channels, designed for simulations of interactions among huge number of relatively simple elements. ARUZ consists of approximately 26 000 FPGAs and it can represent a system composed of several million elemen...

Photogeneration of charge carriers in closely packed phenyl-C61-butyric acid methyl ester (PCBM) was investigated by means of the xerographic discharge technique. It was found, that position of centre of mass of the thermalized electron is positioned at distance which is integral multiplicity of the centre-to-centre distance between the adjacent PC...

An emerging new technology, organic electronics, is approaching the stage of large-scale industrial application. This is due to a remarkable progress in synthesis of a variety of organic semiconductors, allowing one to design and to fabricate, so far on a laboratory scale, different organic electronic devices of satisfactory performance. However, a...

Three new derivatives of carbazole were synthesized, namely two isomers disubstituted with diarylaminophenyl groups in 2,7- and 3,6- positions (C1 and C2) and diarylaminophenyl symmetrically disubstituted with carbazole C3. All three compounds showed similar electrochemical behavior with one reversible redox couple, originating from the oxidation o...

Iridium C,N-cyclometalated complexes of ionic structure are considered to be promising candidates for application in the host/guest solid-state phosphorescent single-layer devices because the employment of such dopants offers the possibility to reduce their concentration in organic matrices as well as allows to obtain organic light emitting devices...

We report a strategy for preparing barium titanate precursor, being the composite of titanate nanosheets (TN) with barium ions (Ba-TN), which subjected to step sintering allows obtaining TiO 2 rich barium titanate ceramics of stoichiometry BaTi 4 O 9 or Ba 2 Ti 9 O 20 . These compounds are important in modern electronics due to their required diele...

Ambipolar organic field-effect transistors based on heterojunction active films still suffer from their unbalanced transport of electrons and holes. This problem is related to an uncontrolled phase separation between the donor and acceptor organic semiconductors in the thin film. In this work, we have developed a concept to improve the phase separa...

Since the interfacial order of conjugated polymers plays an essential role for the performance of field-effect transistors, comprehensive understanding on the charge carrier transport in ultrathin semiconducting films below thicknesses of 10 nm is required for the development of transparent and flexible organic electronics. In this study, ultrathin...

In this work we studied the blends of poly(3-hexylthiophene) (P3HT) with 25–75 wt% of either N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PDIC8) or N,N′-dioctyl-1,7-dicyano-3,4,9,10-perylenedicarboximide (PDIC8CN2). In our approach we used differential scanning calorimetry, X-ray diffraction and atomic force and scanning electron microscopies to sh...

Field-effect transistors based on poly(3-hexylthiophene) (P3HT) bulk films exhibit maximum charge carrier mobilities up to 0.1 cm2/Vs. However, reducing the thickness of the polymer film beyond 10 nm results in significant deterioration of the charge transporting properties. In our work, we demonstrate a strategy towards ultrathin (i.e. thinner tha...

One of the most challenging problems limiting the development of the technology of organic electronics is a lack of simple, solution based, techniques for producing organic thin film transistors (OTFTs) with ambipolar characteristics. In this work, a simple method of manufacturing ambipolar OTFTs, based on a zone-casting technique, is presented. Th...

Three new bipolar star-shaped derivatives of 2,4,6-triphenyl-1,3,5-triazine containing carbazolyl groups were designed, synthesized and characterized. All the materials possess high thermal stability and high glass transition temperatures ranging 97-226 degrees C. Photophysical study of the dilute solutions and neat films of the synthesized compoun...

Systematic studies of redox, spectroscopic and electroluminescent properties of donor-acceptor- donor (DAD) electroactive compounds consisting of diketopyrrolopyrrole central accepting unit symmetrically disubstituted with mono-, bi- or terthiophene (T1, T2 and T3 series) are presented. The potential of the diketopyrrolopyrrole unit reduction is in...

In this work we report a reproducible and efficient method of surface modification of titania nanoparticles (rutile) via reversible-deactivation radical polymerization. Herein, we graft poly(di (ethylene glycol) methyl ether methacrylate) from the surface of TiO 2 in an amount of 21 wt% within the reaction time of 3 h 15 min. The amount of grafted...

Copolymers of 2-(2-methoxyethoxy)ethyl methacrylate (poly(MEO2MA)) are regarded as bioinert replacements of poly(N-isopropylacrylamide) in some biomedical applications. Networks of poly(MEO2MA) of various architecture form thermo-responsive hydrogels. Here, we present dielectric and mechanical spectroscopy studies on segmental motions and network r...

Water interacting with a polymer reveals a number of properties very different to bulk water. These interactions lead to the redistribution of hydrogen bonds in water. It results in modification of thermodynamic properties of water and the molecular dynamics of water. That kind of water is particularly well observable at temperatures below the free...

We report on fabrication and characterization of an organic light emitting diode by incorporating a pure DNA as electron blocking layer. As emission layer a thin film of phosphorescent Ir(ppy)(3) luminophore, embedded in the poly(N-vinylcarbazole) (PVK)/2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) is used. The BioLED shows a good...

Three new naphthalene bisimides with alkoxyphenyl N-substituents (abbreviated as NBI-4-n-ORPhs, where R = butyl, hexyl or octyl group) were synthesized as well as spectroscopically, electrochemically and structurally characterized. DFT calculations predicted a high value of the electron affinity (EA) and a low lying LUMO level for these compounds....

A novel one-step solution based technique to produce bi-functional semiconductor–dielectric composites for organic field effect transistor (OFET) applications has been developed. By changing the parameters and components, one can produce the composites with semiconductors on the top or at the bottom of the polymer film suitable for fabrication of O...

Electronic conductivity in polymer conductors, semiconductors, and insulators is described in terms of mechanisms of charge carrier generation and transport. Basic models of conductivity, specific to different classes of polymer materials (with special emphasis on semiconducting, photoconducting, and conducting polymers), are presented and their im...

In organic electronics solution-processable n-channel field-effect transistors (FETs) matching the parameters of the best p-channel FETs are needed. Progress toward the fabrication of such devices is strongly impeded by a limited number of suitable organic semiconductors as well as by the lack of processing techniques that enable strict control of...

Transparent and air stable organic field effect transistors with ordered layers of dibenzo[d,d]thieno[3,2-b;4,5-b 0 ]dithiophene obtained from solution a b s t r a c t In a search for solution processable and stable p-type semiconductors an analogue of pentacene namely dibenzo[d,d]thieno[3,2-b;4,5-b 0 ]dithiophene (DBTDT) – was tested as an active...

We have studied the structure, microhardness, and thermomechanical properties of poly(styrenebutylacrylate)– magnetite hybrid composites, obtained by the method of suspension polymerization. We have established that composite grains are not susceptible to aggregation and have a spherical shape. By means of Raman spectroscopy, we have detected that,...

We report on the equivalent circuit modeling of the relaxation behavior of an optically-excited thick poly(3-hexylthiophene) (P3HT) film by means of impedance spectroscopy. Fabricated metal-semiconductor-metal devices with Au electrodes showed a nearly perfect ohmic behavior under ambient conditions. Impedance measurements on illuminated P3HT devic...

We report a comparative study of OFET devices based on zone-cast layers of three tetrathiafulvalene (TTF) derivatives in three configurations of electrodes in order to determine the best performing geometry. The first testing experiments were performed using SiO2/Si substrates. Then the optimum geometry was employed for the preparation of flexible...

The phase transition observed by various methods in poly(vinyl methyl ether)/water systems at around 18 degrees C has been assigned by some investigators to the pre-melting of water and by others to a glass transition of the polymer. In this study, broadband dielectric spectroscopy and temperature modulated differential scanning calorimetry were us...

A new theoretical insight into the process of free charge carrier photogeneration in polymers is introduced, based on the fact that increasing intensity of electric field may change the charge dynamics during the dissociation process of geminate pairs of photogenerated charge carriers. These changes are reflected in the model by the variation of in...

New tetraester derivatives of 1,4,5,8-tetraazaanthracene have been prepared and characterized by spectroscopic and electrochemical techniques. The LUMO level of the compounds is close to -4 eV (the so-called air operating stability border in n-channel field effect transistors). Tetraesters were obtained with reasonable yields without the necessity...

We present the application of ultra-high resolution optical coherence tomography (UHR-OCT) in evaluation of thin, protective films used in printed electronics. Two types of sample were investigated: microscopy glass and organic field effect transistor (OFET) structure. Samples were coated with thin (1–3μm) layer of parylene C polymer. Measurements...

Solution prepared single crystal organic field-effect transistors (OFETs) combine low-cost with high performance due to structural ordering of molecules. However, in organic crystals polymorphism is a known phenomenon, which can have a crucial influence on charge transport. Here, the performance of solution-prepared single crystal OFETs based on tw...

Preparation of highly oriented layers of organic semiconductor - dithienothiophene derivative is described. The layers were obtained by zone-casting technique - a solution based one step method that does not require the use of preoriented substrates. Unidirectional alignment of the dithienothiophene derivative molecules in the zone-cast layers was...

We have studied anisotropy of thin layers of amphiphilic tetrathiafulvalene derivatives (TTF-4SCn, with n=12, 18, and 22) obtained by zone-casting technique. All the films show optical anisotropy, as seen by polarized optical microscopy and polarized UV-visible spectroscopy. By using polarized Raman spectroscopy an angular dependence of intensity o...

The electrical properties (dielectric characteristics and conductivity) measured on DC and AC and thermomechanical properties of polyvinylchloride-multiwalled carbon nanotube (PVC/MWNT) nanocomposites were investigated. The segregated PVC/MWCNT composites were formed by the hot compacting method. Measurement of DC and AC conductivity shows a presen...

The new κ-(BEDT-TTF)2SbF6 phase was grown by electrodeposition on a Si(001) electrode. This new phase was characterized by X-ray diffraction (XRD) and electronic conductivity measurements, accompanied by calculations of electronic band structures and Fermi surfaces. Below T=120K, a decrease in the electronic conductivity suggests a phase transition...

The continuous bi-layer composites consisting of top, ordered crystalline layer of perylenediimide derivative (2,9-di(pent-3-yl)-anthra[,1,9-def:6,5,10-d′e′f′]diisoquinoline-1,3,8,10-tetrone) - PTCDI-C5(3) and bottom poly(3-hexylthiophene-2,5-diyl) (P3HT) support were obtained from one solution, with a use of so called “two-step reticulate doping”...

We have investigated the charge carrier trapping and recombination mechanisms in electroluminescent systems based on poly(9-vinylcarbazole)/2-tert-butylphenyl-5-biphenyl-1,3,4-oxadiazole blend, used as the matrix, and the deep blue light-emitting pyrazoloquinoline dye-1-H-pyrazolo[3,4-b]quinoline (PAQ8) dopant. The thermoluminescence studies have s...

a b s t r a c t Raman spectroscopy was used to investigate molecular interactions and structure of water in PVME hydrogels of various crosslinking degrees. Analysis of polymer n(CH 3) and n(CH 2) stretching vibrations has allowed to monitor the changes of hydrophilic and hydrophobic polymer–water interactions in a course of water deswelling and vol...

Several applications of the thermoluminescence (TL) technique for investigations of mechanisms of charge carrier trapping and recombination in electroluminescent polymers which are used for construction of various opto-electronic devices are described. The presented TL studies were focused on polymers emitting blue light, because such emissive mate...

Raman spectroscopy was used to investigate molecular interactions and structure of water in PVME hydrogels of various crosslinking degrees. Analysis of polymer n(CH 3) and n(CH 2) stretching vibrations has allowed to monitor the changes of hydrophilic and hydrophobic polymer–water interactions in a course of water deswelling and volume phase transi...

The new charge transfer salt, BET-TTF[Ni(dmit)2]2, was obtained using the electrodeposition method. Thin layers of this new salt were grown on (001)-oriented silicon wafers as anode. The stoichiometry of the new salt was evaluated by infrared and Raman spectroscopy and the unit cell parameters of its structure were determined by powder X-ray diffra...

Raman spectroscopy is a technique preferably used for studies of water structure because the proportions of intensities of main OH stretching modes are thought to reflect well a network of "intermonomer" hydrogen bonds as well as its disturbance by the presence of some solutes. The work presented herein demonstrates how the intensity ratio of two m...

In this paper we present that the surface energy of silicon dioxide employed as the dielectric in bottom gate organic field effect transistors has large impact on the device performance. By the use of the zone-casting simple solution processing technique, we ensured reproducibility of active layer preparation confirmed by the atomic force microscop...

The thermoluminescence studies of poly(9-vinylcarbazole) (PVK) modified by substitution with halogens (Cl, Br, I) carried out in 15–325K temperature range are reported. Spectral analyses of the thermoluminescence at different temperatures are discussed and compared with the analogues results obtained for unsubstituted PVK. It has been found that in...

Different non-conventional polyurethane networks crosslinked with a hyperbranched polyester (Boltorn®H40) were synthesised with an aim to determine the influence of the polyurethane chemical structure as well as of the length of the linear chains between crosslinking centres on molecular relaxations in such systems. For that purpose, both polyether...

X-ray diffraction investigations show, that in the vacuum evaporated layers of 2,9-di(pent-3yl)-anthra[2,1,9-def:6,5,10-d'e'f']diisoquinoline-1,3,8,10-tetrone (PTCDI) the PTCDI molecules may have edge-on or face-on arrangement. For the samples with different molecular arrangement the dependences of the photogeneration quantum yield on electric fiel...

Molecular relaxations in poly(vinyl methyl ether) hydrogels obtained by electron beam irradiation (range of doses: 13-50 kGy) of 10% polymer solution in water were investigated. Broadband dielectric spectroscopy (10(-1)-10(6) Hz) and differential scanning calorimetry results shown two relaxation processes of the polymer network origin - glass trans...

Several non-conventional polyurethane networks crosslinked with hyperbranched polyester (Boltorn®H30) were synthesised with an aim to determine an influence of the polyurethane linkage length on molecular relaxations in such systems. The polyurethane chain length was regulated by changing the macrodiol length or by changing the number of the repeat...

Investigations into the mechanism of recombination and trapping processes in modified polyfluorenes (PFs) were carried out in order to determine the influence of these phenomena on the electroluminescent properties of PF. The investigated polymers were PFs chemically substituted with triphenylamine derivatives (TPA) and contained from ca. 22 to ca....