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Optical characterization of perovskite via time-resolved spectroscopy
Schlor, Michal ; Kejík, Lukáš (referee) ; Dvořák, Petr (advisor)
This bachelor’s thesis deals with experimental optical characterization of modern organic-anorganic perovskites, which are promised to improve the technology of photovoltaic cells for solar panels soon. Photovoltaic cells based upon these materials bring not only higher efficiency of solar panels, but also relatively simple and cheap manufacture. The first part of this thesis consists of basic structural qualities of perovskites as well as an overview of spectroscopic methods used to examine the properties of perovskites, especially their strong narrow–band photoluminiscence. The second part consists of characterizations of MAPbBr3, FAPbBr3 and MAPbI3 samples based on their photoluminiscence properties.
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Transparent polycrystalline ceramic materials with cubic lattice structure
Kučera, Jan ; Pouchlý, Václav (referee) ; Maca, Karel (advisor)
The presented work is focused on the study of the influence of preparation parameters on the optical properties of polycrystalline cubic ZrO2 (stabilized with 8 mol.% Y2O3). Furthermore, the work deals with the doping of c-ZrO2 with TiO2 and its effect on the luminescence properties of ZrO2. The examined samples were prepared by uniaxial pressing (10 MPa), followed by a cold isostatic pressing (300 and 700 MPa), pressureless sintering (1340–1380 °C, 10 min), and hot isostatic pressing (1200–1400 °C, 4 h, 200 MPa). In this work, it is shown that the optical properties are significantly affected by the temperature of the hot isostatic pressing, the thickness of the sample, and also by the wavelength of the incident light. A maximum real in-line transmission of 68.8 % was achieved, which is 90.5 % of the theoretical limit for c-ZrO2 at an incident radiation wavelength of 632.8 nm. A low-pressure infiltration method and a powder mixing method were used to prepare the doped ZrO2 ceramic sample. With doping, the maximum of the excitation spectrum shifted from 295 nm (4.20 eV) for the undoped ZrO2 to 320 nm (3.87 eV) for the doped samples. Doping led to an increase in emission intensity compared to a pure ZrO2 by up to 23 times. The maximum emission intensity at 545 nm wavelength was achieved for samples doped by infiltration method with a nominal 0.1 mol.% TiO2 content.
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Scanning Near-field Optical Microscopy (SNOM)
Majerová, Irena ; Kvapil, Michal (referee) ; Dvořák, Petr (advisor)
A study of the optical properties of 2D materials has recently been the focus of the broad scientific community for its possible applications in nanophotonics and plasmonics. This bachelor thesis deals with the detection of photoluminiscence (PL) of 2D material (MoS2) by means of near-field scanning optical microscopy (SNOM). This PL is excited in the far-field by means of a focused green laser and in the near-field by surface plasmon polariton (SPP) interference. MoS2 flake monolayers are prepared using micromechanical exfoliation on various functional substrates (metal and dielectric). Characterization and quality of MoS2 monolayers is controlled using Raman optical spectroscopy. Furthermore, the experimentally obtained optical spectra of PL MoS2 are compared in a far-field using confocal optical microscopy and in the near-field using SNOM device, where in the near-field is observed a 3 times higher intensity PL of this 2D material than in the far-field
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Deposition of GaN nanocrystals with Ga droplets
Novák, Jakub ; Voborný, Stanislav (referee) ; Mach, Jindřich (advisor)
This bachelor thesis deals with preparation and characterization of Ga structures and GaN nanocrystals. In the theoretical part, properties and applications of GaN are introduced. Further, some substrates for the growth and some techniques used for manufacturing of these structures are stated. Further, is also mentioned the photoluminiscence of GaN. The experimental part deals with preparation of Ga and GaN structures and combination of both. These structures were further analyzed by various methods such as XPS, SEM or photoluminiscence.
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Study of leaded and lead-free perovskite nanoparticles properties
Holečková, Jana ; Zdražil, Lukáš (referee) ; Zmeškal, Oldřich (advisor)
This master thesis examines optical properties of lead and lead-free perovskite nanoparticles. Two types of perovskite nanoparticle solutions with lead or bismuth were prepared. One type was hybrid inorganic-organic perovskite nanoparticles, either containing bromine anions or chlorine anions. The second type was purely inorganic perovskite nanoparticles, also containing either bromine anions or chlorine anions. During synthesis were used different solvents. Solutions were characterized by dynamic light scattering, fluorescence spektrometry and UV-VIS spectrophotometry. The measured results were discussed.
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Transparent polycrystalline ceramic materials with cubic lattice structure
Kučera, Jan ; Pouchlý, Václav (referee) ; Maca, Karel (advisor)
The presented work is focused on the study of the influence of preparation parameters on the optical properties of polycrystalline cubic ZrO2 (stabilized with 8 mol.% Y2O3). Furthermore, the work deals with the doping of c-ZrO2 with TiO2 and its effect on the luminescence properties of ZrO2. The examined samples were prepared by uniaxial pressing (10 MPa), followed by a cold isostatic pressing (300 and 700 MPa), pressureless sintering (1340–1380 °C, 10 min), and hot isostatic pressing (1200–1400 °C, 4 h, 200 MPa). In this work, it is shown that the optical properties are significantly affected by the temperature of the hot isostatic pressing, the thickness of the sample, and also by the wavelength of the incident light. A maximum real in-line transmission of 68.8 % was achieved, which is 90.5 % of the theoretical limit for c-ZrO2 at an incident radiation wavelength of 632.8 nm. A low-pressure infiltration method and a powder mixing method were used to prepare the doped ZrO2 ceramic sample. With doping, the maximum of the excitation spectrum shifted from 295 nm (4.20 eV) for the undoped ZrO2 to 320 nm (3.87 eV) for the doped samples. Doping led to an increase in emission intensity compared to a pure ZrO2 by up to 23 times. The maximum emission intensity at 545 nm wavelength was achieved for samples doped by infiltration method with a nominal 0.1 mol.% TiO2 content.
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Optical characterization of perovskite via time-resolved spectroscopy
Schlor, Michal ; Kejík, Lukáš (referee) ; Dvořák, Petr (advisor)
This bachelor’s thesis deals with experimental optical characterization of modern organic-anorganic perovskites, which are promised to improve the technology of photovoltaic cells for solar panels soon. Photovoltaic cells based upon these materials bring not only higher efficiency of solar panels, but also relatively simple and cheap manufacture. The first part of this thesis consists of basic structural qualities of perovskites as well as an overview of spectroscopic methods used to examine the properties of perovskites, especially their strong narrow–band photoluminiscence. The second part consists of characterizations of MAPbBr3, FAPbBr3 and MAPbI3 samples based on their photoluminiscence properties.
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