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Publications (10 of 65) Show all publications
Sychugov, I. (2019). Analytical Description of a Luminescent Solar Concentrator Device. Optica, 6, 1046-1049
Open this publication in new window or tab >>Analytical Description of a Luminescent Solar Concentrator Device
2019 (English)In: Optica, Vol. 6, p. 1046-1049Article in journal (Refereed) Published
Place, publisher, year, edition, pages
Optical Society of America, 2019
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-259162 (URN)10.1364/OPTICA.6.001046 (DOI)000482136700017 ()
Note

QC 20190913

Available from: 2019-09-11 Created: 2019-09-11 Last updated: 2019-09-16Bibliographically approved
Vasileva, E., Baitenov, A., Chen, H., Li, Y., Sychugov, I., Yan, M., . . . Popov, S. (2019). Effect of transparent wood on the polarization degree of light. Optics Letters, 44(12), 2962-2965
Open this publication in new window or tab >>Effect of transparent wood on the polarization degree of light
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2019 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 44, no 12, p. 2962-2965Article in journal (Refereed) Published
Abstract [en]

We report on the study of polarization properties of light propagating through transparent wood (TW), which is an anisotropically scattering medium, and consider two cases: completely polarized and totally unpolarized light. It was demonstrated that scattered light distribution is affected by the polarization state of incident light. Scattering is the most efficient for light polarized parallel to cellulose fibers. Furthermore, unpolarized light becomes partially polarized (with a polarization degree of 50%) after propagating through the TW. In the case of totally polarized incident light, however, the degree of polarization of transmitted light is decreased, in an extreme case to a few percent, and reveals an unusual angular dependence on the material orientation. The internal hierarchical complex structure of the material, in particular cellulose fibrils organized in lamellae, is believed to be responsible for the change of the light polarization degree. It was demonstrated that the depolarization properties are determined by the angle between the polarization of light and the wood fibers, emphasizing the impact of their internal structure, unique for different wood species.

Place, publisher, year, edition, pages
OPTICAL SOC AMER, 2019
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-255191 (URN)10.1364/OL.44.002962 (DOI)000471636700005 ()31199356 (PubMedID)2-s2.0-85067943575 (Scopus ID)
Note

QC 20190904

Available from: 2019-09-04 Created: 2019-09-04 Last updated: 2019-09-04Bibliographically approved
Greben, M., Khoroshyy, P., Sychugov, I. & Valenta, J. (2019). Non-exponential decay kinetics: Correct assessment and description illustrated by slow luminescence of Si nanostructures. Applied spectroscopy reviews (Softcover ed.), 54, 758-801
Open this publication in new window or tab >>Non-exponential decay kinetics: Correct assessment and description illustrated by slow luminescence of Si nanostructures
2019 (English)In: Applied spectroscopy reviews (Softcover ed.), ISSN 0570-4928, E-ISSN 1520-569X, Vol. 54, p. 758-801Article in journal (Refereed) Published
Abstract [en]

The treatment of time-resolved (TR) photoluminescence (PL) decay kinetics is analysed in details and illustrated by experiments on semiconductor quantum dots, namely silicon nanocrystals (Si NCs). We consider the mono-, stretch- and multi-exponential as well as lognormal (LN) and some complex decay models for continuous and discrete distribution of rates (lifetimes). A particular attention is devoted to the thorough analysis of non-exponential decay kinetics. We explicitly show that a LN distribution of emitter sizes may results in LN distribution of decay rates. On the other hand, the distribution of rates cannot be, strictly speaking, Levy stable distribution (that results in the stretched-exponential decay). We introduce theoretical background and derive expressions to calculate the average decay lifetimes for some common decays with practical examples of their applications. Experimental aspects are discussed with special attention devoted to the major problems of the accurate TR PL data treatment, including background uncertainty, pulse duration, system response function etc. Finally, a thorough literature survey of TR PL in Si NCs is given. The methods and definitions outlined in this systematic review are applicable to various other material systems with slow decay like rare-earth and transition metal-doped materials, amorphous semiconductors, type-II heterostructures, singlet oxygen phosphorescence etc.

Keywords
Photoluminescence decay, lifetime distribution, average lifetime, silicon nanocrystals
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-259165 (URN)10.1080/05704928.2018.1517263 (DOI)
Note

QC 20191011

Available from: 2019-09-11 Created: 2019-09-11 Last updated: 2019-10-11Bibliographically approved
Sychugov, I., Zhang, M. & Linnros, J. (2019). Non-stationary analysis of molecule capture and translocation in nanopore arrays. Journal of Chemical Physics, 150(8), Article ID 084904.
Open this publication in new window or tab >>Non-stationary analysis of molecule capture and translocation in nanopore arrays
2019 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 150, no 8, article id 084904Article in journal (Refereed) Published
Abstract [en]

Analytical formulas for the ON- and OFF-time distributions as well as for the autocorrelation function were derived for the case of single molecule translocation through nanopore arrays. The obtained time-dependent expressions describe very well experimentally recorded statistics of DNA translocations through an array of solid state nanopores, which allows us to extract molecule and system related physical parameters from the experimental traces. The necessity of non-stationary analysis as opposite to the steady-state approximation has been vindicated for the molecule capture process, where different time-dependent regimes were identified. A long tail in the distribution of translocation times has been rationalized invoking Markov jumps, where a possible sequential ordering of events was elucidated through autocorrelation function analysis. Published under license by AIP Publishing.

Place, publisher, year, edition, pages
AMER INST PHYSICS, 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-247835 (URN)10.1063/1.5060661 (DOI)000460034700030 ()30823763 (PubMedID)2-s2.0-85062398572 (Scopus ID)
Note

QC 20190326

Available from: 2019-03-26 Created: 2019-03-26 Last updated: 2019-04-04Bibliographically approved
Liu, L., Deng, L., Huang, S., Zhang, P., Linnros, J., Zhong, H. & Sychugov, I. (2019). Photodegradation of Organometal Hybrid Perovskite Nanocrystals: Clarifying the Role of Oxygen by Single-Dot Photoluminescence. Journal of Physical Chemistry Letters, 10(4), 864-869
Open this publication in new window or tab >>Photodegradation of Organometal Hybrid Perovskite Nanocrystals: Clarifying the Role of Oxygen by Single-Dot Photoluminescence
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2019 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 10, no 4, p. 864-869Article in journal (Refereed) Published
Abstract [en]

Photostability has been a major issue for perovskite materials. Understanding the photodegradation mechanism and suppressing it are of central importance for applications. By investigating single-dot photoluminescence spectra and the lifetime of MAPbX(3) (MA = CH3NH3+, X = Br, I) nanocrystals with quantum confinement under different conditions, we identified two separate pathways in the photodegradation process. The first is the oxygen-assisted light-induced etching process (photochemistry). The second is the light-driven slow charge-trapping process (photophysics), taking place even in oxygen-free environment. We clarified the role of oxygen in the photodegradation process and show how the photoinduced etching can be successfully suppressed by OSTE polymer, preventing an oxygen-assisted reaction.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-246263 (URN)10.1021/acs.jpclett.9b00143 (DOI)000459948800026 ()30730749 (PubMedID)2-s2.0-85061915174 (Scopus ID)
Note

QC 20190327

Available from: 2019-03-27 Created: 2019-03-27 Last updated: 2019-04-04Bibliographically approved
Liu, L., Zhao, R., Xiao, C., Zhang, F., Pevere, F., Shi, K., . . . Sychugov, I. (2019). Size-Dependent Phase Transition in Perovskite Nanocrystals. Journal of Physical Chemistry Letters, 10(18), 5451-5457
Open this publication in new window or tab >>Size-Dependent Phase Transition in Perovskite Nanocrystals
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2019 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 10, no 18, p. 5451-5457Article in journal (Refereed) Published
Abstract [en]

The complex structure of halide and oxide perovskites strongly affects their physical properties. Here, the effect of dimensions reduced to the nanoscale has been investigated by a combination of single-dot optical experiments with a phase transition theory. Methylammonium lead bromide (CH3NH3PbBr3) nanocrystals with two average particle sizes of ∼2 and ∼4 nm with blue and green photoluminescence, respectively, were spectrally and temporally probed on a single-particle level from 5 to 295 K. The results show that the abrupt blue shift of the photoluminescence spectra and lifetimes at ∼150 K can be attributed to the cubic-to-tetragonal phase transition in the large 4 nm nanocrystals, while this phase transition is completely absent for the small 2 nm particles in the investigated temperature range. Theoretical calculations based on Landau theory reveal a strong size-dependent effect on temperature-induced phase transitions in individual CH3NH3PbBr3 nanocrystals, corroborating experimental observations. This effect should be considered in structure-property analysis of ultrasmall perovskite crystals.

Place, publisher, year, edition, pages
American Chemical Society, 2019
Keywords
Blue shift, Crystal structure, Lead compounds, Nanocrystals, Perovskite, Photoluminescence, Average particle size, Green photoluminescence, Optical experiments, Photoluminescence spectrum, Size-dependent effect, Temperature-induced phase transitions, Theoretical calculations, Transition theories, Particle size analysis
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-262445 (URN)10.1021/acs.jpclett.9b02058 (DOI)000487178900025 ()2-s2.0-85072509029 (Scopus ID)
Note

QC 20191025

Available from: 2019-10-25 Created: 2019-10-25 Last updated: 2019-10-28Bibliographically approved
Chen, H., Baitenov, A., Li, Y., Vasileva, E., Popov, S., Sychugov, I., . . . Berglund, L. (2019). Thickness Dependence of Optical Transmittance of Transparent Wood: Chemical Modification Effects. ACS Applied Materials and Interfaces, 11(38), 35451-35457
Open this publication in new window or tab >>Thickness Dependence of Optical Transmittance of Transparent Wood: Chemical Modification Effects
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2019 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 38, p. 35451-35457Article in journal (Refereed) Published
Abstract [en]

Transparent wood (TW) is an emerging optical material combining high optical transmittance and haze for structural applications. Unlike nonscattering absorbing media, the thickness dependence of light transmittance for TW is complicated because optical losses are also related to increased photon path length from multiple scattering. In the present study, starting from photon diffusion equation, it is found that the angle-integrated total light transmittance of TW has an exponentially decaying dependence on sample thickness. The expression reveals an attenuation coefficient which depends not only on the absorption coefficient but also on the diffusion coefficient. The total transmittance and thickness were measured for a range of TW samples, from both acetylated and nonacetylated balsa wood templates, and were fitted according to the derived relationship. The fitting gives a lower attenuation coefficient for the acetylated TW compared to the nonacetylated one. The lower attenuation coefficient for the acetylated TW is attributed to its lower scattering coefficient or correspondingly lower haze. The attenuation constant resulted from our model hence can serve as a singular material parameter that facilitates cross-comparison of different sample types, at even different thicknesses, when total optical transmittance is concerned. The model was verified with two other TWs (ash and birch) and is in general applicable to other scattering media.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
transparent wood, transmittance, photon diffusion equation, attenuation coefficient, anisotropic scattering
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-262791 (URN)10.1021/acsami.9b11816 (DOI)000488322900100 ()31483595 (PubMedID)2-s2.0-85072687041 (Scopus ID)
Note

QC 20191022

Available from: 2019-10-22 Created: 2019-10-22 Last updated: 2019-10-22Bibliographically approved
Liu, L., Zhao, R., Xiao, C., Zhang, F., Pevere, F., Shi, K., . . . Sychugov, I. (2019). Using Mechanical Stress to Investigate the Rashba Effect in Organic-Inorganic Hybrid Perovskites. Journal of Physical Chemistry Letters, 10(18), 5451-5457
Open this publication in new window or tab >>Using Mechanical Stress to Investigate the Rashba Effect in Organic-Inorganic Hybrid Perovskites
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2019 (English)In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 10, no 18, p. 5451-5457Article in journal (Refereed) Published
Abstract [en]

Organic-inorganic hybrid perovskites simultaneously possess strong spin- orbit coupling (SOC) and structure inversion asymmetry, establishing a Rashba effect to influence light emission and photovoltaics. Here, we use mechanical bending as a convenient approach to investigate the Rashba effect through SOC in perovskite (MAPbI(3-x)Cl(x)) films by elastically deforming grains. It is observed that applying a concave bending can broaden the line shape of the magnetophotocurrent, increasing the internal magnetic parameter B-0 from 121 to 205 mT, which indicates an enhancement on SOC. Interestingly, the PL lifetime is found to be enlarged from 9.9 to 14.8 ns under this bending, which suggests that introducing compressive strain can essentially increase the Rashba effect through SOC, leading to an increase upon indirect band transition. Furthermore, the PL peak associated with the Rashba effect is shifted from 776 to 780 nm under this mechanical bending. Therefore, mechanical bending provides a convenient experimental method to approach the Rashba effect in hybrid perovskites.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
National Category
Physical Chemistry
Identifiers
urn:nbn:se:kth:diva-261956 (URN)10.1021/acs.jpclett.9b01985 (DOI)000487178900025 ()31461614 (PubMedID)2-s2.0-85072508753 (Scopus ID)
Note

QC 20191015

Available from: 2019-10-15 Created: 2019-10-15 Last updated: 2019-10-15Bibliographically approved
Marinins, A., Udalcovs, A., Ozolins, O., Pang, X., Veinot, J., Jacobsen, G., . . . Popov, S. (2018). All-optical intensity modulation in polymer waveguides doped with si quantum dots. In: Optics InfoBase Conference Papers: . Paper presented at CLEO: Applications and Technology, CLEO_AT 2018, 13 May 2018 through 18 May 2018. Optical Society of America
Open this publication in new window or tab >>All-optical intensity modulation in polymer waveguides doped with si quantum dots
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2018 (English)In: Optics InfoBase Conference Papers, Optical Society of America, 2018Conference paper, Published paper (Refereed)
Abstract [en]

We demonstrate all-optical intensity modulation in integrated PMMA optical waveguides doped with silicon quantum dots. The 1550 nm probe signal is absorbed by free carriers excited in silicon quantum dots with 405 nm pump light.

Place, publisher, year, edition, pages
Optical Society of America, 2018
Keywords
Fiber optic sensors, Light modulation, Nanocrystals, Semiconductor quantum dots, Waveguides, 1550 nm, All optical, Free carriers, Polymer waveguides, Probe signals, Pump light, Si quantum dot, Silicon quantum dots, Optical signal processing
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:kth:diva-236442 (URN)10.1364/CLEO_AT.2018.JW2A.31 (DOI)2-s2.0-85049142554 (Scopus ID)9781557528209 (ISBN)
Conference
CLEO: Applications and Technology, CLEO_AT 2018, 13 May 2018 through 18 May 2018
Note

QC 20181025

Available from: 2018-10-25 Created: 2018-10-25 Last updated: 2018-10-25Bibliographically approved
Chulapakorn, T., Primetzhofer, D., Sychugov, I., Suvanam, S. S., Linnros, J. & Hallén, A. (2018). Impact of H-uptake by forming gas annealing and ion implantation on photoluminescence of Si-nanoparticles. Physica Status Solidi (a) applications and materials science, 215(3), Article ID 1700444.
Open this publication in new window or tab >>Impact of H-uptake by forming gas annealing and ion implantation on photoluminescence of Si-nanoparticles
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2018 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 215, no 3, article id 1700444Article in journal (Refereed) Published
Abstract [en]

Silicon nanoparticles (SiNPs) are formed by implanting 70 keV Si+ into a SiO2-film and subsequent thermal annealing. SiNP samples are further annealed in forming gas. Another group of samples containing SiNP is implanted by 7.5 keV H+ and subsequently annealed in N2-atmosphere at 450 °C to reduce implantation damage. Nuclear reaction analysis (NRA) is employed to establish depth profiles of the H-concentration. Enhanced hydrogen concentrations are found close to the SiO2surface, with particularly high concentrations for the as-implanted SiO2. However, no detectable uptake of hydrogen is observed by NRA for samples treated by forming gas annealing (FGA). H-concentrations detected after H-implantation follow calculated implantation profiles. Photoluminescence (PL) spectroscopy is performed at room temperature to observe the SiNP PL. Whereas FGA is found to increase PL under certain conditions, i.e., annealing at high temperatures, increasing implantation fluence of H reduces the SiNP PL. Hydrogen implantation also introduces additional defect PL. After low-temperature annealing, the SiNP PL is found to improve, but the process is not found equivalently efficient as conventional FGA.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
H-quantification, nuclear reaction analysis, photoluminescence, silicon nanoparticles
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-219544 (URN)10.1002/pssa.201700444 (DOI)000424387300006 ()2-s2.0-85031427795 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20171219

Available from: 2017-12-17 Created: 2017-12-17 Last updated: 2018-02-22Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2562-0540

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