Lidé

Ing. Lucie Landová

Všechny publikace

Changes to material phase and morphology due to high-level molybdenum doping of ZnO nanorods: Influence on luminescence and defects

  • Autoři: Buryi, M., Babin, V., Ing. Mgr. Neda Neykova, Ph.D., Wang, Y.-M., Remeš, Z., Ridzoňová, K., Dominec, F., Davydova, M., Drahokoupil, J., Chertopalov, S., Ing. Lucie Landová, Pop-Georgievski, O.
  • Publikace: Materials. 2023, 16(9), 3294-1-3294-18. ISSN 1996-1944.
  • Rok: 2023
  • DOI: 10.3390/ma16093294
  • Odkaz: https://doi.org/10.3390/ma16093294
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    The influence of Mo on the electronic states and crystalline structure as well as morphology, phase purity, luminescence and defects in the ZnO rods grown as free-standing nanoparticles is under study of the bundle of experimental techniques. Mo has almost no influence on luminescence of the as grown ZnO particles whereas shallow donors are strongly affected in ZnO rods.

Effect of UV Irradiation on the Growth of ZnO:Er Nanorods and Their Intrinsic Defects

  • DOI: 10.3390/chemosensors11030156
  • Odkaz: https://doi.org/10.3390/chemosensors11030156
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Nanorods of erbium-doped zinc oxide (ZnO:Er) were fabricated using a hydrothermal method. One batch was prepared with and another one without constant ultraviolet (UV) irradiation applied during the growth. The nanorods were free-standing (FS) as well as deposited onto a fused silica glass substrate (GS). The goal was to study the atomistic aspects influencing the charge transport of ZnO nanoparticles, especially considering the differences between the FS and GS samples. We focused on the excitons; the intrinsic defects, such as zinc interstitials, zinc vacancies, and related shallow donors; and the conduction electrons. UV irradiation was applied for the first time during the ZnO:Er nanorod growth. This led to almost total exciton and zinc vacancy luminescence reduction, and the number of shallow donors was strongly suppressed in the GS samples. The effect was much less pronounced in the FS rods. Moreover, the exciton emission remained unchanged there. At the same time, the Er3+ content was decreased in the FS particles grown under constant UV irradiation while Er3+ was not detected in the GS particles at all. These phenomena are explained.

Hydrothermally grown molybdenum doped ZnO nanorod arrays. The concept of novel ultrafast nanoscintillator

  • Autoři: Buryi, M., Ing. Mgr. Neda Neykova, Ph.D., Brik, M.G., Wang, Y.-M., Remeš, Z., Ridzoňová, K., Babin, V., Davydova, M., Drahokoupil, J., Chertopalov, S., Ing. Lucie Landová, Pop-Georgievski, O.
  • Publikace: Optical Materials. 2023, 145 114445-1-114445-12. ISSN 0925-3467.
  • Rok: 2023
  • DOI: 10.1016/j.optmat.2023.114445
  • Odkaz: https://doi.org/10.1016/j.optmat.2023.114445
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Molybdenum doped ZnO was hydrothermally grown as the arrays of nanorods deposited onto the fused silica glass substrate. The molybdenum doping level varied from 1 to 30%. The influence of Moon the electronic and crystalline structure as well as luminescence and defects in the ZnO nanorods isunder study of the bundle of experimental techniques complemented with density functional theorycalculations. The tendency of Mo to create energy states within the bandgap of ZnO and theirinfluence on the energy levels of native defects as well as excitons were proven by the synergy ofexperiment and theory. The improvement of the timing characteristics of the exciton- and zincvacancy-related emission bands upon Mo doping (1-10%) was observed. This paves the way for the defect engineering strategy in the search of effective and ultrafast scintillator with the improved lightyield as well as compared to other materials. The new concept is based on the combination of theexciton and the defect emission. It is expected to have the potential of application in the detection ofgamma rays implemented in time-of-flight positron emission tomography (TOFPET). The 20 and 30%Mo doping levels resulted in the zinc molybdates creation strongly outnumbering ZnO nanorods.

Peculiarities of erbium incorporation into ZnO microrods at high doping level leading to upconversion and the morphology change. Influence on excitonic as well as shallow donor states

  • Autoři: Buryi, M., Ing. Mgr. Neda Neykova, Ph.D., Ridzoňová, K., Remeš, Z., Děcká, K., Hájek, F., Artemenko, A., Mičová, J., Ing. Lucie Landová, Jakubec, I.
  • Publikace: Applied Surface Science. 2023, 611(Part A), 155651(1)-155651(14). ISSN 0169-4332.
  • Rok: 2023
  • DOI: 10.1016/j.apsusc.2022.155651
  • Odkaz: https://doi.org/10.1016/j.apsusc.2022.155651
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Heavily Er-doped zinc oxide (ZnO) microrods with nominal compositions, ZnO:Er(2, 10, 30%), wereprepared by the hydrothermal growth method. The crystallographic phases present in the as grown and annealed materials were determined. The presence of the hexagonal Wurtzite ZnO phase in the form of the hexagonal shape nanoplatelets and microrods was confirmed. Moreover, the Er2O3 phase in the form of nanosheets has been revealed as well. Erbium is partly incorporated into the ZnO hosts. It was thinning upon erbium doping level contributing to erbium oxide. This effect was even more pronouncedupon annealing in air. Moreover, the influence of erbium doping and annealing on paramagnetic shallow donor centers has been studied.

Peculiarities Related to Er Doping of ZnO Nanorods Simultaneously Grown as Particles and Vertically Arranged Arrays

  • DOI: 10.1021/acs.jpcc.3c05471
  • Odkaz: https://doi.org/10.1021/acs.jpcc.3c05471
  • Pracoviště: Katedra fyziky, Katedra elektrotechnologie
  • Anotace:
    A unique set of undoped and Er doped ZnO nanorods that are grown by a hydrothermal method under the exactly same conditions in the form of 2D nanoarrays on SiO2/ZnO substrate or in a free-standing form on random nucleation seeds in solution were investigated. Their optoelectronic properties are characterized by a photo-, radio-, and cathodoluminescence in correlation with scanning electron microscopy, energy dispersive X-ray spectroscopy, electron paramagnetic resonance spectroscopy, resonance Raman spectroscopy and theoretical computing by using density functional theory. We demonstrate that erbium is incorporated at regular zinc site in the 2D arrays and as additional nucleation seeds in the free-standing nanorods. The deposited nanorods contain larger number of shallow donors (by about two orders of magnitude) and larger number of free carriers (by about one order of magnitude) as compared to the free-standing ones. It is related to the fact that the nanorods grow about one order of magnitude larger and in polycrystalline bunches on the random seeds in solution compared to the deposited arrays. Doping by Er slows down the excitonic emission further from 465 to 522 ps.

Synthesis of the cerium doped Gd3Al3Ga2O12-based glass nanoceramics: Luminescence and optical absorption properties

  • Autoři: Buryi, M., Tratsiak, Y., Trusova, E., Babin, V., Hájek, F., Ing. Lucie Landová,
  • Publikace: Radiation Measurements. 2023, 163 ISSN 1350-4487.
  • Rok: 2023
  • DOI: 10.1016/j.radmeas.2023.106932
  • Odkaz: https://doi.org/10.1016/j.radmeas.2023.106932
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Cerium doped gadolinium gallium aluminum garnet (Gd3Al3Ga2O12, GAGG) was synthesized in the glass ceramics form by the crystallization from Gd2O3–Al2O3–Ga2O3–SiO2–CeO2 glass in the following weight proportion: 101 : 26: 47 : 25: 1. The spatial distribution and incorporation of Ce into the GAGG ceramic grains as well as the luminescence and scintillation performance are studied carrying out correlated experiments of photo-, radio- and cathodoluminescence including decay kinetics as well as energy dispersive X-ray spectroscopy combined with scanning electron microscopy. Optical absorption features were investigated using photothermal deflection spectroscopy. Cerium stays within the material mostly in the Ce3+ charge state. Its distribution in the bulk of the sample exhibits irregular trend indicating the tendency to coalesce in the middle.

Charge traps in Zn- and Mo-based oxide microstructures. The role of Mo

  • Autoři: Buryi, M., Ridzoňová, K., Artemenko, A., Děcká, K., Ing. Lucie Landová,
  • Publikace: Journal of Physics: Conference Series. Praha: Fyzikální ústav AV ČR, v. v. i., 2022. vol. 2413. ISSN 1742-6588.
  • Rok: 2022
  • DOI: 10.1088/1742-6596/2413/1/012007
  • Odkaz: https://doi.org/10.1088/1742-6596/2413/1/012007
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Peculiarities of the point defects creation under the X-ray irradiation and the influence of Mo doping in ZnO: Mo (10 and 30%) and MoO3 micro-powders fabricated by the hydrothermal growth method were studied in detail. It has been found that some new phases other than ZnO are created upon the heavy molybdenum doping. They were tentatively ascribed to complex zinc molybdates existing in the form of platelet flakes. The MoO3 sample contained both hydrated and anhydrous MoO3 phases in the form of microneedles. The molybdenum charge state was Mo6+ before X-ray irradiation in all the materials. X-ray irradiation resulted in creation of molybdenum- and oxygen-based charge trapping centres, i.e., Mo5+ and O- or O2-. Part of them is expected to exist in the pure ZnO and MoO3 phases whereas the rest must appear in the complex zinc molybdates.

Influence of Mo doping on the luminescence properties and defect states in ZnO nanorods. Comparison with ZnO:Mo thin films

  • Autoři: Buryi, M., Remeš, Z., Babin, V., Novotný, M., Ing. Lucie Landová,
  • Publikace: Applied Surface Science. 2021, 555 ISSN 0169-4332.
  • Rok: 2021
  • DOI: 10.1016/j.apsusc.2021.149679
  • Odkaz: https://doi.org/10.1016/j.apsusc.2021.149679
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    ZnO:Mo powders of nano- and microrods were fabricated by the hydrothermal growth method. ZnO:Mo thin films deposited on a fused silica glass substrate. The samples were also annealed in air at elevated temperatures to study the defects and luminescence modification. In particular, EPR spectra in the powder and thin film samples were composed of the signals originating from shallow donors before any treatment. The Mo5+ signal appeared after the annealing at 350 ◦C in the powder spectra. It existed prior to the treatment in the thin film samples. New EPR signal appears after X-ray irradiation in the powder samples. Red luminescence occurs in all powder samples. It depends on the annealing temperatures and Mo content. The exciton-related band at 380 nm never observed in the powder samples before the annealing, appears after the annealing at 350 ◦C. The strongest it was in the ZnO:Mo powder with low Mo content.

Pulsed laser deposition of high-transparency molybdenum oxide thin films

  • DOI: 10.1016/j.vacuum.2021.110613
  • Odkaz: https://doi.org/10.1016/j.vacuum.2021.110613
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Molybdenum oxide is an intensively studied material, thanks to its high bandgap, high work function, and potentially also photochromism, plasmonic properties, and layered structure. In this contribution, we employ Pulsed Laser Deposition (PLD) from stoichiometric MoO3 and metal Mo target at temperature range of 25 °C – 500 °C and oxygen pressure variation of 0.1 mbar – 0.4 mbar to deposit high transparency MoO3 layers. The combination of Photothermal Manuscript File Click here to view linked ReferencesDeflection Spectroscopy (PDS) and Spectral Ellipsometry is applied to accurately track all the optical properties. The X-ray diffraction and Scanning Electron Microscopy (SEM) are used to monitor crystallinity and surface morphology.

Stabilization of light emitting Eu2+ centers inside Ca(Sr)I-2:Eu particles in glass ceramics. The preliminary concept of synthesis

  • Autoři: Buryi, M., Salamakha, T., Babin, V., Páterek, J., Hájek, F., Ing. Lucie Landová,
  • Publikace: Ceramics International. 2021, 47(20), 29232-29252. ISSN 0272-8842.
  • Rok: 2021
  • DOI: 10.1016/j.ceramint.2021.07.088
  • Odkaz: https://doi.org/10.1016/j.ceramint.2021.07.088
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Glass ceramics in the form of MI2 :Eu crystalline particles grown in MO-B2O3 glass (M = Ca, Sr, Ba) through recrystallization from the alloyed melt were fabricated. Eu2+ ions were detected in the CaI2 and SrI2 crystalline particles (not in the BaI2) inside the corresponding glasses. Some amount of Eu2+ centers are expected to originate from the MO-B2O3 glass hosts as well. This was confirmed by correlated electron paramagnetic resonance (EPR), photo- and radioluminescence (PL, RL) measurements. Peculiarities of the Eu2+ distribution and incorporation into the glass ceramics samples as well as charge and energy transfer properties are discussed in detail. Optimal conditions leading to the enhancement of the Eu2+ emission from the CaI2 and SrI2 crystallites inside the glasses were determined.

Transformation of free-standing ZnO nanorods upon Er doping

  • Autoři: Buryi, M., Remeš, Z., Babin, V., Artemenko, A., Ing. Lucie Landová,
  • Publikace: Applied Surface Science. 2021, 562 ISSN 0169-4332.
  • Rok: 2021
  • DOI: 10.1016/j.apsusc.2021.150217
  • Odkaz: https://doi.org/10.1016/j.apsusc.2021.150217
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Erbium doped zinc oxide (ZnO:Er) powder was synthesized by hydrothermal growth. The morphology changed from undoped nanorods to microrods. The effect of Er doping on luminescence properties of ZnO:Er was observed. Furthermore, annealing in air at elevated temperatures up to 700 ◦C results in additional modification of defect states and related luminescence properties.

TRANSFORMATION OF ZNO-BASED STRUCTURES UNDER HEAVY MO DOPING: DEFECT STATES AND LUMINESCENCE

  • Autoři: Buryi, M., Remeš, Z., Děcká, K., Ing. Lucie Landová,
  • Publikace: Conference Proceedings - NANOCON 2021, 13th International Conference on Nanomaterials - Research & Application. Ostrava: Tanger Ltd., 2021. p. 74-79. ISSN 2694-930X. ISBN 978-80-88365-00-6.
  • Rok: 2021
  • DOI: 10.37904/nanocon.2021.4321
  • Odkaz: https://doi.org/10.37904/nanocon.2021.4321
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Hydrothermally grown ZnO-based structures were heavily doped with Mo (various doping levels from 2 to 25%). Mo was found to strongly affect the structure and morphology of ZnO, resulting in a complex mixture of zinc oxide and molybdenum. Moreover, the transformation of material phases upon the increased Mo content was observed. ZnO phase was observed only at low Mo doping level (2 and 5%). This correlated very well to the changes in the luminescence and electron paramagnetic resonance signals.

Unveiling the Effect of Potassium Treatment on the Mesoporous TiO2/ Perovskite Interface in Perovskite Solar Cells

  • DOI: 10.1021/acsaem.1c02229
  • Odkaz: https://doi.org/10.1021/acsaem.1c02229
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    A method for improving mesoporous TiO2/perovskite interfacial characteristics in perovskite solar cells (PSCs) is demonstrated by modifying mesoporous TiO2 with potassium (K) treatment. It is found that the modification of mesoporous TiO2 with K treatment enhances the perovskite crystallization process, producing a perovskite film with higher crystallinity and larger grains. K treatment passivates trap sites in mesoporous TiO2 and reduces sub-band-gap deep defect states at the interface of the perovskite, thereby suppressing the nonradiative recombination and improving Voc of PSCs. Stronger photoluminescence quenching and shorter carrier lifetime are also observed for the perovskite on K-treated mesoporous TiO2, indicating more efficient charge collection across the interface. As a result of these advancements, PSC based on K-treated mesoporous TiO2 shows a high power conversion efficiency of 20.60% compared to PSC without K treatment and improves the environmental stability in air

Controlled Growth of Large Grains in CH3NH3PbI3 Perovskite Films Mediated by an Intermediate Liquid Phase without an Antisolvent for Efficient Solar Cells

  • DOI: 10.1021/acsaem.0c02441
  • Odkaz: https://doi.org/10.1021/acsaem.0c02441
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Crystalline large grains with uniform morphologies of the perovskite films are important for achieving stable, high-performance perovskite solar cells. Herein, a strategy to control the growth of grains in CH3NH3PbI3 films is demonstrated by modifying the perovskite film deposition process through forming an intermediate CH3NH3PbI3·methylammonium chloride (MACl)·xCH3NH2 liquid phase induced by CH3NH2 gas treatment in combination with MACl additive. By tuning the incorporation of MACl additive to the perovskite precursor solution, this intermediate phase enables the controlled growth of grains up to 3 μm, uniform morphology, and high crystallinity in the films. The high-quality CH3NH3PbI3 film leads to enhanced carrier lifetime and reduced charge-trap density and nonradiative recombination of perovskite films. Solar cells made via CH3NH3PbI3·MACl·xCH3NH2 phase exhibit high power conversion efficiency of 18.4%, higher than solar cells made without MACl (15.8%).

Elucidating the role of TiCl(4)post-treatment on percolation of TiO(2)electron transport layer in perovskite solar cells

  • DOI: 10.1088/1361-6463/ab938c
  • Odkaz: https://doi.org/10.1088/1361-6463/ab938c
  • Pracoviště: Katedra elektrotechnologie, Katedra řídicí techniky
  • Anotace:
    The ideal electron transport layer of a high performance perovskite solar cell should have good optical transparency, high electron mobility, and an energy level alignment well-matched with the perovskite material. In this work, we investigate the role of TiCl(4)post-treatment of the mesoporous TiO(2)electron transport layer by varying the concentration of TiCl(4)and characterizing optical and electrical properties, charge carrier dynamics, and photovoltaic performance of mesoscopic CH(3)NH(3)PbI(3)solar cells. It is found that the TiCl(4)treatment provides an additional interconnection between the TiO(2)particles, leading to better percolation as evident from high resolution cross-section images and chemical maps. This enhances effective electron mobility in the material as well as significantly reduces average sub-bandgap absorption due to defects and electronic disorder determined by photothermal deflection spectroscopy.

Impact of Cation Multiplicity on Halide Perovskite Defect Densities and Solar Cell Voltages

  • Autoři: Ledinský, M., Vlk, A., Schönfeldová, T., doc. Mgr. Jakub Holovský, Ph.D., Aydin, E., Dang, H.X., Hájková, Z., Ing. Lucie Landová, Valenta, J., Fejfar, A., De Wolf, S.
  • Publikace: Journal of Physical Chemistry C. 2020, 124(50), 27333-27339. ISSN 1932-7447.
  • Rok: 2020
  • DOI: 10.1021/acs.jpcc.0c08193
  • Odkaz: https://doi.org/10.1021/acs.jpcc.0c08193
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Metal-halide perovskites feature very low deep-defect densities, thereby enabling high operating voltages at the solar cell level. Here, by precise extraction of their absorption spectra, we find that the low deep-defect density is unaffected when cations such as Cs+ and Rb+ are added during the perovskite synthesis. By comparing single crystals and polycrystalline thin films of methylammonium lead iodide/bromide, we find these defects to be predominantly localized at surfaces and grain boundaries. Furthermore, generally, for the most important photovoltaic materials, we demonstrate a strong correlation between their Urbach energy and open-circuit voltage deficiency at the solar cell level. Through external quantum yield photoluminescence efficiency measurements, we explain these results as a consequence of nonradiative open-circuit voltage losses in the solar cell. Finally, we define practical power conversion efficiency limits of solar cells by taking into account the Urbach energy

Optical characterization of low temperature amorphous MoOx, WOX, and VOx prepared by pulsed laser deposition

  • DOI: 10.1016/j.tsf.2019.137690
  • Odkaz: https://doi.org/10.1016/j.tsf.2019.137690
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Transition metal oxides are materials combining properties of electrical conductivity, optical transparency, and catalytical function. They are widely used in applications including solar cells, flat panel displays, and detectors. In particular, high work function oxides such as MoO3, WO3, and V2O5 have become popular. In many applications, low deposition temperatures are required, leading to amorphous structure. In this study, thin films of amorphous MoOX, WOX, and VOX were prepared by pulsed laser deposition, and their optical properties and work function were determined. Samples of polycrystalline ZnO were also prepared for comparison. Substrate temperature was varied in the range of 25 °C–100 °C and oxygen pressure was varied in the range of 10–20 Pa during the process. Effect of pressure during sample cool-down and chamber venting was also observed.. Optical characterization was based on photothermal deflection spectroscopy, which is a non-contact and non-destructive method for measuring directly absorptance spectra with sensitivity down to 10–4. Absorptance in the band gap serves as an indication of the presence of defects such as oxygen vacancies or metallic phases. Our optimized films achieved a sub-bandgap absorption coefficient as low as 103 cm−1 for MoOX, VOX, and 102 cm−1 in the case of the WOX. From the gradient of the absorption edge, Urbach energy was obtained, evaluating disorder in the semiconductor material. The work function of each material was obtained by Kelvin probe, and a slight correlation with Urbach energy was found. X-ray photoelectron spectroscopy indicated successful stochiometric transfer mainly for the lowest pressure and highest temperature samples.

Concentration-Dependent Impact of Alkali Li Metal Doped Mesoporous TiO2 Electron Transport Layer on the Performance of CH3NH3PbI3 Perovskite Solar Cells

  • DOI: 10.1021/acs.jpcc.9b05355
  • Odkaz: https://doi.org/10.1021/acs.jpcc.9b05355
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    TiO2 is commonly employed as an electron transport layer (ETL) in mesoscopic n−i−p perovskite solar cells (PSCs). However, the low electron mobility, low electrical conductivity, and high electronic trap states of TiO2 have negative impacts on further enhancement of PSC performance. Metal doping is an efficient way to improve the electronic properties of TiO2 films. In this work, we investigate the concentration-dependent impact of alkali lithium metal doping of the mesoporous TiO2 ETL on the performance of mesoscopic CH3NH3PbI3 PSCs. It was found that Li doping results in improvement in electrical conductivity and electron mobility and reduces the number of electronic trap states arising due to the oxygen vacancies within TiO2 lattice. The device performance relies on the concentration of Li doping, and the power conversion efficiency (PCE) of the PSC was improved from 13.64% to 17.59% for a Li doped mesoporous TiO2 layer with an optimized concentration of 30 mg/mL.

Deep levels, charge transport and mixed conductivity in organometallic halide perovskites

  • Autoři: Musiienko, A., Moravec, P., Grill, R., Ing. Lucie Landová,
  • Publikace: ENERGY & ENVIRONMENTAL SCIENCE. 2019, 12(4), 1413-1425. ISSN 1754-5692.
  • Rok: 2019
  • DOI: 10.1039/c9ee00311h
  • Odkaz: https://doi.org/10.1039/c9ee00311h
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Organometallic halide perovskites (OMHPs) have recently undergone a remarkable development as highly efficient optoelectronic materials for a variety of applications particularly solar cells, light emitting diodes and photodetectors. To fully use the potential of OMHPs, several important challenges must be overcome. One of these challenges is the understanding and control of their defect structures. The available data from multiple research studies suggest that trap-assisted recombination exists in OMHPs despite their large carrier lifetimes, which makes these materials highly attractive, and this has resulted in the perovskite boom over the last decade. Conventional spectroscopy faces serious obstacles in OMHPs due to their low defect concentrations and capture cross section, and therefore the electronic structure of such semiconductors remains poorly understood. By using highly specialized photo-Hall effect spectroscopy, we visualized the deep level defects responsible for non-radiative recombination and established their parameters in the MAPbBr3 perovskite. The presented deep level model in combination with Time of Flight measurements demonstrated that the electron transport is mostly affected by the trap-assisted recombination. Meanwhile, holes are only influenced by the partially filled deep level. The presented electrical and charge transport properties are crucial for informing the processing conditions towards the elimination of these defects as was done for classical inorganic semiconductors.

Effect of a-Si on CH3NH3PbI3 Films and Applications in Perovskite Solar Cells

  • Autoři: Conrad, B., Müller, M., Remeš, Z., Ing. Lucie Landová, Horák, L., Peter Amalathas, A., doc. Mgr. Jakub Holovský, Ph.D.,
  • Publikace: IEEE Photovoltaic Specialists Conference. New York: Institute of Electrical and Electronics Engineers, 2019. p. 451-456. ISSN 0160-8371. ISBN 978-1-7281-0494-2.
  • Rok: 2019
  • DOI: 10.1109/PVSC40753.2019.8980569
  • Odkaz: https://doi.org/10.1109/PVSC40753.2019.8980569
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    The effect of PECVD deposition of amorphous Silicon on perovskite layers, and perovskite layers prepared on pre-deposited a-Si are investigated in the interest of determining the interaction between the two materials and developing a-Si as a material for direct integration into perovskite cells. This may include as selective contacts or carrier transport layers, an encapsulation material, or in other ways. Doped and intrinsic a-Si layers are deposited at a range of temperatures, with the resulting structures characterized by methods including photoluminescence, SEM imaging, absorption, resistivity measurements, and degradation rate. Comparisons are made to layers deposited on glass without any PECVD deposition carried out and layers subjected to heating without PECVD deposition. The implications for use of a-Si in perovskite cells are explored.

Lead Halide Residue as a Source of Light-Induced Reversible Defects in Hybrid Perovskite Layers and Solar Cells

  • DOI: 10.1021/acsenergylett.9b02080
  • Odkaz: https://doi.org/10.1021/acsenergylett.9b02080
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Advanced characterization methods avoiding transient effects in combination with solar cell performance monitoring reveal details of reversible light-induced perovskite degradation under vacuum. A clear signature of related deep defects in at least the 1 ppm range is observed by low absorptance photocurrent spectroscopy. An efficiency drop, together with deep defects, appears after minutes-long blue illumination and disappears after 1 h or more in the dark. Systematic comparison of perovskite materials prepared by different methods indicates that this behavior is caused by the lead halide residual phase inherently present in material prepared by the two-step method. X-ray photoelectron spectroscopy confirms that lead halide when illuminated decomposes into metallic lead and mobile iodine, which diffuses into the perovskite phase, likely producing interstitial defects. Single-step preparation, as well as preventing lead halide illumination, eliminates this effect.

Temperature Dependence of the Urbach Energy in Lead Iodide Perovskites

  • DOI: 10.1021/acs.jpclett.9b00138
  • Odkaz: https://doi.org/10.1021/acs.jpclett.9b00138
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    To gain insight into the properties of photovoltaic and light-emitting materials, detailed information about their optical absorption spectra is essential. Here, we elucidate the temperature dependence of such spectra for methylammonium lead iodide (CH3NH3PbI3), with specific attention to its sub-band gap absorption edge (often termed Urbach energy). On the basis of these data, we first find clear further evidence for the universality of the correlation between the Urbach energy and open-circuit voltage losses of solar cells. Second, we find that for CH3NH3PbI3 the static, temperature-independent, contribution of the Urbach energy is 3.8 ± 0.7 meV, which is smaller than that of crystalline silicon (Si), gallium arsenide (GaAs), indium phosphide (InP), or gallium nitride (GaN), underlining the remarkable optoelectronic properties of perovskites.

Improved Contactless Method of IR Reflectance under Grazing Incidence for Measurement of Doping Profiles

  • Autoři: doc. Mgr. Jakub Holovský, Ph.D., Remeš, Z., Franta, D., Conrad, B., Ing. Lucie Landová, Ing. David Bušek, Ph.D., Poruba, A.
  • Publikace: Proceedings of the International Conference of 35th European Photovoltaic Solar Energy Conference and Exhibition. München: WIP Wirtschaft und Infrastruktur GmbH & Co Planungs KG, 2018. p. 278-280. ISSN 2196-100X. ISBN 978-3-936338-50-8.
  • Rok: 2018
  • DOI: 10.4229/35thEUPVSEC20182018-2AO.5.3
  • Odkaz: https://doi.org/10.4229/35thEUPVSEC20182018-2AO.5.3
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    We have elaborated contactless method of measurement and evaluation of doping profiles in silicon polished wafers based on infrared reflectance under high angle of incidence. We have found higher angle of incidence increases sensitivity, however approaching Brewster angle increases also experimental error, therefore 65 angle has been chosen. Moreover, to increase reproducibility we divide the measured spectra by reference spectra taken on an undoped sample, and further we rescale the spectra to fixed value in the region of 4000 cm-1–7000 cm-1. To reduce number of evaluated parameter, the carrier profile in boron-doped samples was parametrized by 3 parameters and that in phosphorous-doped samples was parametrized by 4 parameters, using additional empirically determined assumption that the first part of the profile is a constant plateau and that the following two exponential tails are joined at a value of 3x10^19 cm-3.

Measurement of doping profiles by a contactless method of IR reflectance under grazing incidence

  • DOI: 10.1063/1.5015988
  • Odkaz: https://doi.org/10.1063/1.5015988
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    The grazing angle infrared reflectance method of the measurement and evaluation of charge carrier profiles in polished wafers was developed. Experimental errors were minimized by division by reference spectra taken on an undoped sample and further by normalization to a fixed value in the region of 4000/cm to 7000/cm. The carrier profile in boron-doped samples was parametrized by 3 parameters and that in phosphorous-doped samples was parametrized by 4 parameters, using additional empirically determined assumptions. As a physical model, the Drude equation is used with two parameters assumed to be concentration-dependent: relaxation time and contribution from band-to-band excitations. The model parameters were calibrated independently by infrared ellipsometry. The presented method gives results in satisfactory agreement with the profiles measured by the electrochemical capacitance-voltage method.

Perovskity – nový fenomén ve fotovoltaice

  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    Organicko-anorganické perovskity se nedávno ukázaly jako nadějný materiál pro výrobu levných tenkovrstvých slunečních článků s vysokou účinností. Příspěvek představuje strukturu perovskitů, jednoduché metody jejich přípravy a slibnou perspektivu tandemového slunečního článku perovskitu s křemíkem. Zmíněny jsou též dvě slabiny, které zatím brání komerční výrobě perovskitových slunečních článků.

Probing Photoinduced Degradation of CH3NH3PbI3 Perovskite Films by Kelvin Probe and Photoluminescence Techniques

  • DOI: 10.4229/35thEUPVSEC20182018-3DO.4.5
  • Odkaz: https://doi.org/10.4229/35thEUPVSEC20182018-3DO.4.5
  • Pracoviště: Katedra elektrotechnologie
  • Anotace:
    In this work, the photoinduced degradation of CH3NH3PbI3 perovskite films under illumination in ambient conditions (relative humidity 30-50%) was studied by Kelvin Probe and Photoluminescence techniques. Using Kelvin Probe techniques, we investigated the effects on the work function of the CH3NH3PbI3 film on fluorine-doped SnO2 (FTO) at various photoinduced degradation states in the dark and under illumination. It was found that the work function of CH3NH3PbI3 film on FTO was gradually increased in the dark after every 10 min illumination step until the film was completely degraded. The gradual increase in work function due to the degradation can be ascribed to modulation doping of the CH3NH3PbI3 by PbI2 phase. It was also found that the contact potential difference (CPD) of CH3NH3PbI3 on FTO was increased under illumination as a result of a positive surface photovoltage relative to the FTO.

Za stránku zodpovídá: Ing. Mgr. Radovan Suk