Персона: Самохвалов, Павел Сергеевич
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Инженерно-физический институт биомедицины
Цель ИФИБ и стратегия развития – это подготовка высококвалифицированных кадров на базе передовых исследований и разработок новых перспективных методов и материалов в области инженерно-физической биомедицины. Занятие лидерских позиций в биомедицинских технологиях XXI века и внедрение их в образовательный процесс, что отвечает решению практикоориентированной задачи мирового уровня – диагностике и терапии на клеточном уровне социально-значимых заболеваний человека.
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- ПубликацияТолько метаданныеLong-range coupling of individual quantum dots with plasmonic nanoparticles in a thin-film hybrid material(2020) Rakovich, Y. P.; Dyagileva, D. V.; Krivenkov, V. A.; Samokhvalov, P. S.; Nabiev, I. R.; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович© 2020 SPIE.Semiconductor quantum dots (QDs) are widely used in photovoltaic and optoelectronic devices due to their unique optical properties. Photoluminescence (PL) properties of QDs can be significantly improved by their electromagnetic coupling with plasmonic nanoparticles (PNPs). The excitation of resonant localized plasmon modes leads to the enhancement of the density of photon states and increase of electromagnetic field near the surface of PNPs, what boosts the acceleration of the exciton radiative decay, known as the Purcell effect. To study the dependence of the degree of acceleration of radiative decay rate (Purcell factor) on the distance between QDs and PNPs, we fabricated thin-film hybrid structures based on CdSe(core)/ZnS/CdS/ZnS(multishell) QDs and silver or gold PNPs with a controllable distance between these components. The change in the radiative decay rate of excitons was calculated from the PL intensities and lifetimes before and after the deposition of PNPs on top of the QD thin film covered by a poly(methyl methacrylate) (PMMA) spacer. For both PNP types, the PL lifetime of underlying QDs decreased, whereas the PL intensity of the latter decreased only slightly for gold PNPs and even increased for silver PNPs. This indicates the acceleration of QDs radiative decay (Purcell effect) mediated by exciton-plasmon interaction. The Purcell factor was higher for silver PNPs than that for gold PNPs, what can be explained by the better spectral overlap between the QDs PL band and silver PNPs absorbance and the absence of interband absorption in silver at the wavelength of QDs PL. The results of this study provide better understanding of the Purcell effects in hybrid materials based on QDs and PNPs.
- ПубликацияТолько метаданныеOptical Properties of Quantum Dots with a Core–Multishell Structure(2019) Linkov, P.; Samokhvalov, P.; Vokhmintsev, K.; Zvaigzne, M.; Krivenkov, V. A.; Nabiev, I.; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович© 2019, Pleiades Publishing, Inc. In the last decade, colloidal semiconductor nanocrystals (quantum dots) have been not only studied fundamentally but also applied in photovoltaics, optoelectronics, and biomedicine. Beginning with simple approaches to the deposition of protective shells, e.g., ZnS on CdSe cores, searches for ways to increase the quantum yield of photoluminescence of quantum dots have resulted now in the development of new types of quantum dots characterized not only by record high extinction coefficients but also by high photoluminescence quantum yields. In this work, the optical properties of core–multishell quantum dots have been analyzed. These quantum dots have been specially designed to reach the maximum possible localization of excited charge carriers inside luminescent cores, which makes it possible to reach a photoluminescence quantum yield close to 100%. Core–multishell quantum dot samples with a shell thickness of 3–7 monolayers have been fabricated. Changes in the characteristics of optical transitions in such quantum dots with an increase in the number of layers of the shell have been studied. The effect of the thickness of the shell on the optical properties of prepared quantum dots has been analyzed. In particular, analysis of photoluminescence lifetimes of such quantum dots has revealed a possible alternative mechanism of radiation of core–multishell quantum dots based on the slow charge carrier transfer from the excited outer layer of the CdS shell to the CdSe core.
- ПубликацияТолько метаданныеRemarkably enhanced photoelectrical efficiency of bacteriorhodopsin in quantum dot – Purple membrane complexes under two-photon excitation(2019) Krivenkov, V.; Samokhvalov, P.; Nabiev, I.; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович© 2019 Elsevier B.V. The photosensitive protein bacteriorhodopsin (bR)has been shown to be a promising material for optoelectronic applications, but it cannot effectively absorb and utilize light energy in the near-infrared (NIR)region of the optical spectrum. Semiconductor quantum dots (QDs)have two-photon absorption cross-sections two orders of magnitude larger than those of bR and can effectively transfer the up-converted energy of two NIR photons to bR via the Förster resonance energy transfer (FRET). In this study, we have engineered a photoelectrochemical cell based on a hybrid material consisting of QDs and bR-containing purple membranes (PMs)of Halobacterium salinarum and demonstrated that this cell can generate an electrical signal under the two-photon laser excitation. We have shown that the efficiency of light conversion by the PM–QD hybrid material under two-photon excitation is up to 4.3 times higher than the efficiency of conversion by PMs alone. The QD integration into the bR-containing PMs significantly improves the bR capacity for utilizing light upon two-photon laser excitation, thus paving the way to the engineering of biologically inspired hybrid NIR nonlinear optoelectronic elements. The nonlinear nature of two-photon excitation may provide considerable advantages, such as a sharp sensitivity threshold and the possibility of precise three-dimensional location of excitation in holography and optical computing.
- ПубликацияТолько метаданныеConversion of Semiconductor Nanoparticles to Plasmonic Materials by Targeted Substitution of Surface-Bound Organic Ligands(2019) Samokhvalov, P. S.; Volodin, D. O.; Bozrova, S. V.; Dovzhenko, D. S.; Zvaigzne, M. A.; Lin'kov, P. A.; Nifontova, G. O.; Petrova, I. O.; Sukhanova, A. V.; Nabiev, I. R.; Самохвалов, Павел Сергеевич; Нифонтова, Галина Олеговна; Суханова, Алена Владимировна; Набиев, Игорь Руфаилович© 2019, Pleiades Publishing, Ltd.Abstract: Plasmonic nanoparticles have become a popularly accepted research tool in optoelectronics, photonics, and biomedical applications. The relatively recently appearing semiconductor plasmonic nanoparticles, as opposed to metal ones, are characterized by infrared plasmonic optical transitions and their application has a great future. In this work, the possibility of conversion of semiconductor (excitonic) fluorescence nanocrystals, i.e., quantum dots of the CuInS2 composition, to plasmonic nanoparticles by postsynthetic treatment without changes in the chemical composition of inorganic part of the nanocrystals was demonstrated for the first time ever.
- ПубликацияТолько метаданныеDirect Demonstration of Biexciton Quantum Yield Enhancement in an Individual Quantum Dot Coupled with Gold Nanoparticles in a Thin-film Hybrid Material(2019) Krivenkov, V.; Samokhvalov, P.; Nabiev, I.; Rakovich, Y.; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович
- ПубликацияТолько метаданныеpH-Sensing Platform Based on Light-Matter Coupling in Colloidal Complexes of Silver Nanoplates and J-Aggregates(2021) Rakovich, Y. P.; Krivenkov, V.; Samokhvalov, P.; Nabiev, I.; Самохвалов, Павел Сергеевич; Набиев, Игорь Руфаилович© 2021 American Chemical Society.Remote control of the pH of the medium is an important task for many applications in chemistry, medicine, and biology. Remote control of the pH using light is an intelligent and cost-effective approach. The nanoscale plasmon-exciton (plexciton) light-matter coupling is a physical phenomenon that provokes strong changes in the optical properties of the original plasmon and exciton bands, resulting in a transparency dip in the initial plasmon spectrum and formation of two hybrid plexciton side bands separated by the Rabi splitting energy. The plexciton coupling strength is unaffected by the temperature and light irradiation stressors but strongly depends on the transition dipole moment of the exciton material. Here, we show that the optical parameters of the plexciton coupling can be controlled by varying the pH of the medium. To demonstrate this, we obtained resonant light-matter coupling between the plasmon band of silver nanoplates and the J-band of J-aggregates with a Rabi splitting energy of up to 450 meV and found that both the extinction dip and the splitting energy are strongly affected by variation of pH from 2.5 to 11. We explain this effect by a change in the structure of the J-aggregates and reduction of the J-band intensity, which is confirmed by numerical simulation.
- ПубликацияТолько метаданныеTwo-photon-activated light energy conversion in quantum dot-purple membrane hybrid material(2019) Krivenkov, V. A.; Samokhvalov, P. S.; Nabiev, I.; Самохвалов, Павел Сергеевич; Набиев, Игорь РуфаиловичThe photosensitive protein bacteriorhodopsin (bR) has been shown to be a promising material for optoelectronic and photovoltaic applications, but it cannot effectively absorb and utilize light energy in the near-infrared (NIR) region of the optical spectrum. Semiconductor quantum dots (QDs) have two-photon absorption cross-sections two orders of magnitude larger than those of bR and can effectively transfer the up-converted energy of two NIR photons to bR via the Forster resonance energy transfer (FRET). In this study we fabricated a hybrid material in the form of an aqueous solution of electrostatically bound complexes of QDs and purple membranes (PMs) containing bR. Efficient FRET from QDs to bR was observed in these complexes under selective two-photon excitation of QDs. Then, we fabricated a photoelectrochemical cell operating in the NIR spectral region. Measurement of the photoelectrical signals from the cell containing pure PMs, or QD-PM hybrid material has shown that the light conversion in the QD-PM hybrid material with 3:1 bR-to-QD molar ratio is more efficient than in the material with 20:1 bR-to-QD molar ratio. The results of this study may extend the use of bioinspired hybrid materials in optoelectronics, holography, and bioenergetics under the conditions of nonlinear excitation.
- ПубликацияТолько метаданныеAnisotropic nanomaterials for asymmetric synthesis(2021) Zvaigzne, M.; Samokhvalov, P.; Gun'ko, Y. K.; Nabiev, I.; Самохвалов, Павел Сергеевич; Гунько, Юрий Кузьмич; Набиев, Игорь РуфаиловичThe production of enantiopure chemicals is an essential part of modern chemical industry. Hence, the emergence of asymmetric catalysis led to dramatic changes in the procedures of chemical synthesis, and now it provides the most advantageous and economically executable solution for large-scale production of chiral chemicals. In recent years, nanostructures have emerged as potential materials for asymmetric synthesis. Indeed, on the one hand, nanomaterials offer great opportunities as catalysts in asymmetric catalysis, due to their tunable absorption, chirality, and unique energy transfer properties; on the other hand, the advantages of the larger surface area, increased number of unsaturated coordination centres, and more accessible active sites open prospects for catalyst encapsulation, partial or complete, in a nanoscale cavity, pore, pocket, or channel leading to alteration of the chemical reactivity through spatial confinement. This review focuses on anisotropic nanomaterials and considers the state-of-the-art progress in asymmetric synthesis catalysed by 1D, 2D and 3D nanostructures. The discussion comprises three main sections according to the nanostructure dimensionality. We analyze recent advances in materials and structure development, discuss the functional role of the nanomaterials in asymmetric synthesis, chirality, confinement effects, and reported enantioselectivity. Finally, the new opportunities and challenges of anisotropic 1D, 2D, and 3D nanomaterials in asymmetric synthesis, as well as the future prospects and current trends of the design and applications of these materials are analyzed in the Conclusions and outlook section.
- ПубликацияТолько метаданныеPlasmon-exciton interaction strongly increases the efficiency of a quantum dot-based near-infrared photodetector operating in the two-photon absorption mode under normal conditions(2021) Krivenkov, V.; Samokhvalov, P.; Vasil'evskii, I. S.; Kargin, N. I.; Nabiev, I.; Самохвалов, Павел Сергеевич; Васильевский, Иван Сергеевич; Каргин, Николай Иванович; Набиев, Игорь РуфаиловичSemiconductor quantum dots (QDs) are known for their high two-photon absorption (TPA) capacity. This allows them to efficiently absorb infrared photons with energies lower than the bandgap energy. Moreover, TPA in QDs can be further enhanced by the interaction of excitons of the QDs with plasmons of a metal nanoparticle. We fabricated nonlinear plasmon-exciton photodetectors based on QDs and silver nanoplates (SNPs) to demonstrate the optoelectronic application of these effects. A thin layer of CdSe QDs was used as a source of charge carriers for a photoresistor-type photodetector. SNPs with near-infrared plasmon modes were introduced into the layer of QDs to increase the light absorption efficiency. Under near-infrared irradiation, the power of the dependence of the photocurrent on the excitation intensity was twice the power of the corresponding dependence under one-photon excitation with visible light. This proved that the new photodetector efficiently operated under two-photon excitation. Although the SNP light absorption was linear, energy was transferred from plasmons to excitons in the two-quantum mode, which led to a nonlinear dependence. Moreover, we found that the photocurrent from the designed photodetector containing the QD-SNP composite was an order of magnitude higher than that from a photodetector containing QDs alone. This can be explained by the plasmon-induced increase in the TPA efficiency.
- ПубликацияТолько метаданныеOptimizing the PMMA electron-blocking layer of quantum dot light-emitting diodes(2021) Alexandrov, A.; Lypenko, D.; Zvaigzne, M.; Tkach, A.; Nabiev, I.; Samokhvalov, P.; Набиев, Игорь Руфаилович; Самохвалов, Павел Сергеевич© 2021 by the authors. Licensee MDPI, Basel, Switzerland.Quantum dots (QDs) are promising candidates for producing bright, color-pure, costefficient, and long-lasting QD-based light-emitting diodes (QDLEDs). However, one of the significant problems in achieving high efficiency of QDLEDs is the imbalance between the rates of charge-carrier injection into the emissive QD layer and their transport through the device components. Here we investigated the effect of the parameters of the deposition of a poly (methyl methacrylate) (PMMA) electron-blocking layer (EBL), such as PMMA solution concentration, on the characteristics of EBL-enhanced QDLEDs. A series of devices was fabricated with the PMMA layer formed from acetone solutions with concentrations ranging from 0.05 to 1.2 mg/mL. The addition of the PMMA layer allowed for an increase of the maximum luminance of QDLED by a factor of four compared to the control device without EBL, that is, to 18,671 cd/m2, with the current efficiency increased by an order of magnitude and the turn-on voltage decreased by ~1 V. At the same time, we have demonstrated that each particular QDLED characteristic has a maximum at a specific PMMA layer thickness; therefore, variation of the EBL deposition conditions could serve as an additional parameter space when other QDLED optimization approaches are being developed or implied in future solid-state lighting and display devices.