Oleg P Dimitriev

• PhD
• Senior Researcher at National Academy of Sciences of Ukraine

Cellulose-based materials can be classified as non-conventional luminogens that produce photoluminescence (PL) in the visible range due to specific intermolecular arrangements. Usually such an arrangement is referred to as clusterization. Here, we demonstrate the importance of intramolecular arrangement of ethyl cellulose and bacterial cellulose th...

Cellulose-based materials can be classified as non-conventional luminogens that produce photoluminescence (PL) in the visible range due to specific intermolecular arrangements. Usually such an arrangement is referred to as clusterization. Here, we demonstrate the importance of intramolecular arrangement of ethyl cellulose and bacterial cellulose th...

Carbon dots (CDs) are recognized as promising fluorescent nanomaterials with bright emission and large variations of photoluminescence quantum yield (PLQY). However, there is still no unique approach for explanation of mechanisms and recipes for synthetic procedures/chemical composition of CDs responsible for the enhancement of PLQY. Here, we compa...

Carbon quantum dots (CQDs) are recognized as promising fluorescent nanomaterials possessing high thermal stability, tuned photoluminescence, along with the low cost of their production. Quantum yield (QY) of photoluminescence (PL) of CQDs is known to vary largely depending on the synthetic procedures/ chemical composition of CQDs, but there is stil...

Functionalization of colloidal nanoparticles with organic dyes, which absorb photons in complementary spectral ranges, brings a synergistic effect for harvesting additional light energy. Here, we show functionalization of near-infrared (NIR) plasmonic nanoparticles (NPs) of bare and amino-group functionalized mesoporous silica-coated copper sulphid...

The concept of exciton implies a collective excited state able to travel in a particle-like fashion. Its size is determined by the radius of excited electron-hole pair and, although it may vary by two orders of magnitude, it is always spatially restricted, while its delocalization length owing to the exciton wavefunction spatial dynamics may provid...

Single-photon hot-band absorption-assisted anti-Stokes photoluminescence (ASPL) is a non-equilibrium process which causes a local cooling effect and which therefore is accompanied by a reverse heat flux from the warmer environment. Here, we demonstrate that the thermal properties of the medium, i.e., its thermal conductivity and specific heat capac...

Anti-Kasha emission (i.e., the emission from Sn (n > 1) excited levels) of infrared chromophores which possess intensive absorption and S1 emission in the near-infrared region, but which are spectrally silent in the visible, is a challenging task for relevant applications such as energy conversion, bioimaging, sensitization of solar cells, optical...

Aggregation-induced emission of organic dyes is a phenomenon in which organic luminophores show higher photoluminescence (PL) efficiency in the aggregated state than in a free molecule, due to the freezing rotational degrees of freedom of the luminophore which otherwise quench the PL emission. In many cases, however, coupling of molecules leads to...

In this work, we demonstrate a novel prototype for a composite artificial muscle where specific filler is used to improve its mechanical and thermal conducting properties. Specifically, the muscle is based on the composite of silicone rubber and carbon fiber. The latter serves for reinforcement of the mechanical strength of the elastomer and improv...

To clarify the mechanism of a photoinduced charge transport in films of relatively small organic molecules, i.e., whether it is stimulated by energetic and/or structural disorder, three types of films composed of a specific tricarbocyanine near-infrared dye were prepared, i.e., a polycrystalline film, an amorphous film composed of a mixture of mono...

A series of new tricarbocyanine near-infrared (NIR) dyes is demonstrated which are able for a single-photon vibronic-assisted anti-Stokes luminescence with a large, up to 147 nm (225 meV), anti-Stokes shift of the excitation energy. It is shown that quantum yield of the anti-Stokes emission depends on both the dye substituents, which bear different...

The large photovoltaic response from homogeneous silicon wafer obtained upon deposition of a molecular layer on its surface remained an unexplained phenomenon so far. Here, we show by X-ray and ultraviolet photoelectron spectroscopy that deposition of species containing acidic groups on the surface of n-type silicon with native silicon oxide overla...

Time, with no doubt, can be compared with the strongest drug which the modern humanity is dependent on. We look at the watch dozen times per day, being constantly in a hurry and definitely wanting to prolong our lives. But time is very reluctant to let us in and does not give a chance to be finally conquered. This book "What does your clock show?"...

We have found electrochemical self-assembly (ESA) of inorganic / organic hybrid thin films in which the inorganic is CuSCN, known as a wide bandgap p-type semiconductor, whereas the organic is 4- N,N -dimethylamino-4’- N’ -methylstilbazolium chromophore (abbreviated as DAS) as its salt with tosylate (DAST) known to exhibit second-order nonlinear op...

Whether they are inorganic or organic, the key words for creation of new functional materials should be (1) solution, (2) low temperature, and (3) rare-element-free for sustainable development. As a leading example, we explore electrochemical self-assembly (ESA) of inorganic / organic hybrid thin films. In addition to the interests to study evoluti...

Here, the ability of a novel near‐infrared dye to noncovalently self‐assemble onto the surface of single‐walled carbon nanotubes (SWCNTs) driven by charge‐transfer interactions is demonstrated. Steady‐state, Raman, and transient absorption spectroscopies corroborate the electron donating character of the near‐infrared dye when combined with SWCNTs,...

Спосіб синтезу нанокристалів кадмію селеніду в колоїдному розчині з прекурсорів кадмію, селену та модифікатора в розчиннику в атмосфері аргону при нагріванні, який відрізняється тим, що синтез проводять при нагріванні з дефлегматором при температурі 70-80 °C впродовж 30-40 хв при постійному перемішуванні, як прекурсор селену використовують селеносу...

Спосіб отримання прекурсору селену для синтезу нанокристалів кадмію селеніду з чистого елементарного селену у відповідному розчиннику в атмосфері аргону при нагріванні, який відрізняється тим, що отримання прекурсору здійснюють при нагріванні з дефлегматором при температурі 70-80 °C протягом 3-5 днів при постійному перемішуванні, як розчинник викор...

Energy storage is one of the most important energetic strategies of the mankind, along with other energy challenges, such as development of energy resources, energy conversion and energy saving. The problem of energy storage is especially actual in respect to renewable sources of energy, such as sun, wind, tides, which have seasonal or diurnal vari...

Infrared (IR) energy constitutes almost a half of the solar radiation coming to the Earth surface and almost 100% of the outgoing terrestrial radiation. Surprisingly, but such a huge energy flux is mostly considered as thermal waste and is not used for the practical needs on the large scale. Here, two major methods of the IR energy collection have...

Description of excitation energy transfer (EET) in large multichromophoric systems of nanoscale size is often inconsistent with the classical Förster model. In this work, abnormal enhancement of emission in heterogeneous mixture of J-aggregates of donor and acceptor thiamonomethinecyanine dyes is reported, which surpasses the sum of emissions of th...

Hot-band absorption assisted anti-Stokes photoluminescence (ASPL) in the near infrared region is demonstrated using specific tricarbocyanine dye, with the large anti-Stokes shift of 100 nm. Intensity of the ASPL is shown to correlate with intensity of the hot-band absorption through population of the vibronic levels during heating. CCC bending of t...

Visualization of functionally different domains in bulk heterojunction (BHJ) solar cells is of paramount importance to understand the routes of optimization of their structure for best performance. In this work, a concept of detecting n-type and p-type semiconductor domains in BHJ structures by methods based on atomic force microscopy (AFM) is prop...

Electrochemical self-assembly of CuSCN/4-(N,N-dimethylamino)-4′-(N′-methyl)stilbazolium (DAS) hybrid thin films has been carried out on systematic variation of bulk concentrations of [Cu(SCN)]⁺, DAS tosylate (DAST) and changing their flux density by angular speed of rotation of the rotating disk electrode. Switching of DAS loading mechanism depende...

Hybrid thin films of crystalline CuSCN and 4-(N,N-dimethylamino)-4′-(N′-methyl)stilbazolium (DAS) in three distinctively different nanostructures were obtained by electrochemical self-assembly from a single pot containing all the chemical ingredients. Their optical properties for UV-vis-NIR absorption, photoluminescence (PL), and PL excitation spec...

The next 6th technological cycle is starting just now and will be mainly concentrated on the following technologies: nano-, bio-, info- and cogno- (NBIC). For that matter, the tasks of Ukrainian society could be separated into two spheres: education and R&D. The world trend in education is the creation of NBIC faculties for manpower grounding in an...

Arrangement of polymer chains at the interface with an acceptor is one of the key issues which influence the interfacial charge transfer. Films of P3HT and P3HT:PCBM blends with the different polymer chain arrangement have been prepared from one-component and binary solvents representing a mixture of chloroform and different poor solvents with high...

Excimer in J-aggregates has been often considered as a self-trapped exciton originated from the free exciton excited on the same aggregate and relaxed through interaction with vibronic modes. Here we show that other type of excimers due to intermolecular off-diagonal interactions can be observed in J-aggregates of thiamonomethinecyanine dyes. These...

Mechanochemically prepared nanopowder of selenium-free kesterite Cu2ZnSnS4 (CZTS) in combination with n-type semiconductors, i.e., CdS, ZnO and TiO2, was tested in planar and bulk-heterojunction solar cells. The samples have been studied by macroscopic current-voltage (I-V) measurements and Kelvin-probe atomicforce microscopy (KPFM). KPFM images ta...

Mechanochemically prepared nanopowder of selenium-free kesterite Cu2ZnSnS4 (CZTS) in combination with n-type semiconductors, i.e., CdS, ZnO and TiO2, was tested in planar and bulk-heterojunction solar cells. The samples have been studied by macroscopic current-voltage (I-V) measurements and Kelvin-probe atomic-force microscopy (KPFM). KPFM images t...

The influence of arrangement of poly(3-hexylthiophene) (P3HT) chains embedded into poly(methyl methacrylate) (PMMA) matrix on photophysical properties, such as electronic absorption spectrum, band gap, and photoluminescence quantum yield, of the formed P3HT aggregates have been studied. It has been found that variation of P3HT fraction in PMMA matr...

Ultraviolet photoelectron spectroscopy was used to study energy levels of (0001) and (0001_) surfaces of bare CdS crystal terminated with Cd and S atoms, respectively, as well as energy level alignment at hybrid interfaces of CdS crystal and donor zinc phthalocyanine (PcZn) or acceptor fluoro-substituted zinc phtalocyanine (F-PcZn) layers, respecti...

A broadband upconverted emission due to the use of different types of molecular aggregates of the same organic infrared dye is demonstrated; one type of aggregate serves as a broadband absorber (from ∼700 to 1000 nm) and the other as a broadband emitter (from ∼450 to 700 nm).

In this work, a method to assemble nanoscale hybrid solar cells in the form of a brush of radially oriented CdS nanowire crystals around a single carbon fiber is demonstrated for the first time. A solar cell was assembled on a carbon fiber with a diameter of ~5-10 μm which served as a core electrode; inorganic CdS nanowire crystals and organic dye...

A behavior of polyaniline (PANI) composites with common polymers under different conditions is often a result of a synergetic combination of properties of their components. In this work we consider specificity of such a combination in terms of both hydrogen bonding of PANI with a matrix polymer poly(ethylene terephthalate) (PET) and its influence o...

An ordered array of CdS nanocrystals was synthesized by vapor-solid mechanism using a template of chemically inhomogeneous pores in the form of nanocavities in a thin silicon nitride layer on a SiO2/Si wafer. The silicon oxide at the bottom of the Si3N4 cavities served for nucleation of the CdS crystals, whereas no affinity of CdS to silicon nitrid...

Mutual influence of thiamonomethinecyanine dye and PEDOT:PSS in the dye–polymer composite solutions and films was studied. It was found that PSS tends to suppress formation of J-aggregates of the dye molecules in the solution, while there is a competition between sulfonic groups of dye and PSS for binding with the PEDOT backbone. Interaction of dye...

We demonstrate here a multifunctional application of CdS layers with nanotextured and nanowire morphology in four types of hybrid solar cells, i.e., (i) nanocrystal-polymer cell, (ii) nanocrystalorganic donor–acceptor bulk heterojunction (BHJ) inverted cell, (iii) nanocrystal-dye sensitized solid state cell and (iv) nanocrystal-dye sensitized elect...

Formation of J aggregates, that is, one-dimensional supramolecular self-organizations in which the transition moments of individual molecules are aligned parallel to the line joining their centers through a “head-to-tail” arrangement, normally proceed via electrostatic interactions between oppositely charged molecular groups; this is facilitated by...

Rhodanine derivatives of merocyanine dyes with residues of 1,3,3-trimethyl-3H-indole and 3-ethylbenzothiazoline have been found to possess two molecular forms in diluted solutions of polar solvents such as dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidinone. The first molecular form was observed to prevail at low concentrations of the...

Two pairs of benz[c, d]indole dyes with the same chromophore in each pair have been studied in respect to their ability to form thin films through thermal evaporation in vacuum. Electronic absorption spectra of the films revealed that despite very slight variations in molecular structure different aggregate structures can be formed in the films. It...

Magnetically charged particle or monopole theoretically predicted by Dirac almost a century ago still remains elusive, because it has not been revealed experimentally. So, should we continue to hunt for it? Instead, this work aims to establish charge symmetry in Maxwell electrodynamics and to explain electric charge quantization without attracting...

Thin films of copper phthalocyanine (CuPc) have been prepared by vacuum thermal evaporation in the absence and in the presence of an applied electric field during film growth. It was found that both the film structure and its electrical properties were noticeably modified by the external field. Namely, molecular stacks become more ordered and condu...

Three types of hybrid solar cells based on CdS nanowire crystals have been prepared, i.e., (i) nanocrystal - polymer, (ii) nanocrystal - dye and (iii) nanocrystal - organic donor-acceptor bulk heterojunction (BHJ), and the role of CdS layer in each of the above structures has been elucidated. It has been found that CdS plays the active role of acce...

An inverted solar cell has been constructed by the growth of a CdS layer on an indium tin oxide (ITO)/glass substrate followed by spin-coating of organic poly(3-hexylthiophene) : [6,6]-phenyl C61-butyric acid methyl ester (P3HT : PCBM) or a zinc phthalocyanine derivative (ZnPc-4R): PCBM composite layer and using a free-standing PEDOT : PSS composit...

Nanocrystallin CdS films with controlled stoichiometry deposited by CSVS were investigated by method of the current-voltage characteristics in ITO/CdS /In structures. It was shown that in the case of cadmium excess (S <Cd) charge flow mechanism both in the dark and under illumination is determined by bimolecular recombination in the material. In th...

The difference in the growth conditions, crystalline structure and morphology of CdS nanowire crystals synthesized via the vapor–solid (VS) mechanism on bare substrates and via the vapor–liquid–solid (VLS) mechanism using gold catalyst, respectively, has been studied. It has been found that the growth of CdS nanowire crystals by the VS mechanism de...

A conductive pyrolytic carbon fiber (CF) has been found to serve as an alternative material to metal electrodes, since it forms an Ohmic contact to CdS crystals. The methods of preparation of polycrystalline layers and nanocrystalline arrays of CdS are described that allow formation of an ohmic or quasi-ohmic contact to CF. It is shown that the ohm...

The conditions of formation of J-aggregates for three types of thiamonomethincyanine dyes, whose structure is differed by end groups, are studied depending on their concentration and type of interaction with CdTe nanoparticles with size of about 3 nm in aqueous dispersions. The influence of dye structure on the efficiency of formation of J-aggregat...

A 30-fold increase in the quantum yield of fluorescence of pseudoisocyanine (PIC) J-aggregates in the vicinity of CdTe nanocrystals has been revealed as a result of the resonant energy transfer from the nanocrystals to PIC J-aggregates in aqueous solutions. This enormous effect was accompanied by rather modest (~30%) energy transfer efficiency and...

Каково происхождение разума? Что такое мышление? Как мы мыслим? Почему мы принимаем то или иное решение? Почему мы не понимаем друг друга? Каждый мыслящий человек хотя бы раз в жизни задумывался над этими вопросами. Данное исследование представляет собой попытку приоткрыть дверь в неуловимую природу человеческого мышления и попытаться понять его пр...

Composite CdSe:poly(3-methylthiophene) (P3MT) nanoparticles have been synthesized via polymerization of 3-methylthiophene (3MT) in the presence of CdSe particles of nanorod or dot-like morphology and dispersed in the poly(3-hexylthiophene) (P3HT) matrix. The effect of the P3MT layer to mediate charge and energy transfer between CdSe and P3HT in the...

This paper critically reviews the foundation principles of the charge quantization problem based on introduction of monopole. Closely following the Dirac’s approach we show that there is an alternative way of solution of the above problem by changing topology of the surface through which the magnetic flux emanates. This way leads to introduction of...

This report considers the global energy consumption from the viewpoint of thermodynamic balance between the Earth and the cosmic environment. To follow such a b alance is postulated to be necessary to maintain proper functioning of the biosphere and stable climate conditions on the Earth. This viewpoint implies the following principles of energy co...

Interaction of emeraldine base of polyaniline (PANI) and poly(ethylene-3,4-dioxythiophene): poly(styrenesulfonic acid) (PEDOT:PSS) in a complex solution is shown to lead to a new polymer complex whose components act to each other to favor an increase in intramolecular conductivity in both PANI and PEDOT backbones. Asymmetric changes in intramolecul...

Interaction of emeraldine base (EB) of polyaniline (PANI) with tetraalkylammonium hydroxides (TAAHs) has been studied in N-methylpyrrolidinone solutions and complex films. The spectral changes in the solutions at the early stage of the interaction showed features typical of the increased intramolecular conductivity in PANI backbone, which has been...

A different effect of (0001) and (000{1}) crystal facets of the cadmium sulfide (CdS) wurtzite structure terminated with Cd and S atoms, respectively, was observed in respect to the properties of the crystal surface and interface with metal or organic semiconductor contacts. In addition to the different surface morphology, a bare CdS single crystal...

We report the synthesis and properties of new hybrid nanocomposites of poly(3-methylthiophene) and CdSe nanoparticles. The synthesis method is based on the chemical oxidative polymerization of 3-methylthiophene in the presence of CdSe nanoparticles of different shapes (quantum dots, nanorods, and tetrapods). In situ, the open circuit potential and...

Poly(3-hexylthiophene) (P3HT) belongs to the family of conducting polymers whose conductivity can be controlled via doping. This paper is intended to study iodine doping-dedoping processes in P3HT films via in-situ measurements of the conductivity and light absorption. The film was spin-coated on ITO (indium tin oxide) patterned in the form of fou...

Photoluminescence, electronic absorption, and pH studies of a poly(ethylene-3,4-dioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) dispersion as a function of the PEDOT:PSS concentration are shown to provide a better understanding of the effect of PSS on the intramolecular conductivity of PEDOT chains. Particularly, concentration changes of PED...

The study results of the influence of lattice crystal field on the structure of the IR vibrational bands in the tetrahedral sublattice of the crystal (P04)3- with the isomorphous anionic substitution of compounds Ca10(PO4)6-X(VO4)X(M)2, where M = OH-, F-, CI-, x = 0, 1, 3, 5, 6 were considered. It was established that the decrease in of IR absorpti...

CdTe nanocrystals were prepared in aqueous solution by the reaction between Cd 2+ and H 2 Te, obtained electrochemically in a galvanostatic cell, in the presence of thioglycolic acid. Subsequently, we have investigated precipitation of monodisperse fractions of CdTe quantum dots from polydisperse colloid solutions. In addition, the photoluminescenc...

Hybrid organic-inorganic heterostructures have been produced using the conducting polymer PEDOT:PSS and three types of semiconductor single crystals, i.e., high-ohmic and low-ohmic cadmium sulphide (CdS, n-type semiconductor) and low-ohmic cadmium telluride (CdTe, p-type semiconductor). A photovoltaic (PV) response was observed upon light illuminat...

The behaviour of a hybrid heterojunction (HJ) of an inorganic semiconductor cadmium sulfide (CdS) single crystal (102 Ω cm) and an organic conducting polymer poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonic acid) (PEDOT : PSS) has been studied using electrical and photoelectrical measurements as well as ultraviolet photoelectron spectroscop...

Photovoltaic (PV) response of hybrid organic/inorganic bilayer heterostructures based on organic polymers or small molecules on the one hand, such as poly(3-hexylthiophene), polyaniline doped with poly(styrenesulfonic acid), poly(ethylene-3,4-dioxythiophene) doped with poly(styrenesulfonic acid) (PEDOT:PSS), phthalocyanine, and inorganic CdS or CdS...

We report results on conductivity of PEDOT:PSS films, which contain different amounts of organic solvents, i.e., dimethyl sulphoxide (DMSO) or ethylene glycol (EG), and annealed at different temperatures. The maximum of conductivity of the resulting films was reached at about 5wt.% of DMSO or EG in the solution. At the same time, the presence of th...

Bulk heterojunction (BHJ) photovoltaic (PV) cells have been prepared by vacuum co-deposition of inorganic cadmium sulfide (CdS) and organic zinc phthalocyanine (PcZn) materials. Characteristics of the BHJ cells were compared with the cells based on vacuum evaporated bilayer CdS/PcZn heterojunctions, and it was found that the BHJ structure possesses...

Process of formation of polyaniline (PANI) at the surface of SiC and CdS nanoparticles or submicron- and micron-sized particles of poly(vinylidene fluoride) (PVDF), polycarbonate and polyamides-11, 12 and properties of the prepared composites are considered. Beginning of the formation of the PANI shell at the particle surface was evaluated. This im...

Formation of complex polyaniline (PANI) films with diamagnetic TCNQ and paramagnetic metal ion impurities cast under applied magnetic field was studied. It has been found that the applied magnetic field affects interaction of PANI chains with the impurities and induces formation of magnetically ordered regions in the complex film doped by paramagne...

Abstract Formation of complex polyaniline (PANI) films with diamagnetic TCNQ and paramagnetic metal ion impurities cast under applied magnetic field was studied. It has been found that the applied magnetic field affects interaction of PANI chains with the impurities and induces formation of magnetically ordered regions in the complex film doped by...

The processes of intramolecular and polymer-to-particle energy transfer as well as charge separation at the organic/inorganic interface in acetonitrile dispersions and composite films based on a novel processible copolymer of aniline with 3-methylthiophene and CdS or CdSe nanoparticles have been studied. The copolymer was synthesized by chemical ox...

Hybrid photovoltaic (PV) cells based on cadmium sulphide (CdS) single crystal and phthalocyanine (Pc) films have been developed and their PV performance was measured. Five different Pcs have been selected as candidates for the PV cell, PcCu, PcMn, PcZn, PcMg, and PcVO. It was found that all the chosen Pcs are capable of forming a hybrid heterojunct...

The doping of semiconductor nanoparticles is introduced and examined via doping of cadmium sulfide nanoparticles both by chemical bath deposition route with In3+ cations and by thermal annealing route with Cl− anions. The CdS nanoparticles (10–20 nm in size) were prepared by mixing CdCl2 and Na2S solutions stabilized with pyridine both in absence a...

Nanorods and nanotubes as photoactive materials as well as electrodes in photovoltaic cells have been launched a few years ago, and the literature in this field started to appear only recently. The first steps have shown both advantages and disadvantages of their application, and the main expectation associated with their effective charge transport...

Formation of associates of N,N-dimethylformamide (DMF) molecules was studied to clarify their role in photoluminescent activity of protonated DMF solutions. The association of DMF molecules was observed in dilute aqueous solutions at concentrations of DMF above approximately 4x10(-2) M. The association is enhanced when the CO bond of the DMF molecu...

Suppression of the benzenoid-to-quinoid excitonic transition (BQET) and enhancement of the quantum yield of photoluminescence (PL) at ∼390 nm has been observed in grained films of the emeraldine base (EB) of polyaniline. The major PL band from the EB films with the grained morphology was relatively narrow, with FWHM of about 1020 cm−1, followed by...

A novel method of preparation of organic films is described, which employs an alternating magnetic field applied to the film cast from a solution and results in an improved film morphology. The changed film morphology is explained by a magnetomechanical effect due to the interaction of the applied field and the induced magnetic moment in an organic...

This work is an attempt to reconsider the concept of monopole that is usually used to establish a charge symmetry in Maxwell electrodynamics. An alternative approach is proposed that is based on kinematics of a spinning motion and that leads to the new equations which are considered to be counterparts of the Maxwell equations. Specificity of the ne...