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1. Effect of the crystallographic c-axis orientation on the tribological properties of the few-layer PtSe2

Author

Kozak, Andrii, Sojkova, Michaela, Gucmann, Filip, Bodik, Michal, Vegso, Karol, Dobrocka, Edmund, Pis, Igor, Bondino, Federica, Hulman, Martin, Siffalovic, Peter, and Tapajna, Milan

Subjects
Condensed Matter - Materials Science
Abstract

Two-dimensional (2D) transition metal dichalcogenides are potential candidates for ultrathin solid-state lubricants in low-dimensional systems owing to their flatness, high in-plane mechanical strength, and low shear interlayer strength. Yet, the effects of surface topography and surface chemistry on the tribological properties of 2D layers are still unclear. In this work, we performed a comparative investigation of nanoscale tribological properties of ultra-thin highly-ordered PtSe2 layers deposited on the sapphire substrates with the in-plane and out-of-plane crystallographic orientation of the PtSe2 c-axis flakes, and epitaxial PtSe2 layers. PtSe2 c-axis orientation was found to has an impact on the nanotribological, morphological and electrical properties of PtSe2, in particular the change in the alignment of the PtSe2 flakes from vertical (VA) to horizontal (HA) led to the lowering of the coefficient of friction from 0.21 to 0.16. This observation was accompanied by an increase in the root-mean-square surface roughness from 1.0 to 1.7 nm for the HA and VA films, respectively. The epitaxial films showed lower friction caused by lowering adhesion when compared to other investigated films, whereas the friction coefficient was similar to films with HA flakes. The observed trends in nanoscale friction is attributed to a different distribution of PtSe2 structure.

Published
2022
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10. Evolution of Defects, Morphology, and Strain during FAMAPbI3Perovskite Vacuum Deposition: Insights from In Situ Photoluminescence and X-ray Scattering

Author

Held, Vladimir, Mrkyvkova, Nada, Halahovets, Yuriy, Nádaždy, Peter, Vegso, Karol, Vlk, Aleš, Ledinský, Martin, Jergel, Matej, Bernstorff, Sigrid, Keckes, Jozef, Schreiber, Frank, and Siffalovic, Peter

Abstract

At present, the power conversion efficiency of single-junction perovskite-based solar cells reaches over 26%. The further efficiency increase of perovskite-based optoelectronic devices is limited mainly by defects, causing the nonradiative recombination of charge carriers. To improve efficiency and ensure reproducible fabrication of high-quality layers, it is crucial to understand the perovskite nucleation and growth mechanism along with associated process control to reduce the defect density. In this study, we investigate the growth kinetics of a promising narrow bandgap perovskite, formamidinium methylammonium lead iodide (FAMAPbI3), for high-performance single-junction solar cells. The temporal evolution of structural and optoelectronic properties during FAMAPbI3vacuum codeposition was inspected in real time by grazing-incidence wide-angle X-ray scattering and photoluminescence. Such a combination of analytical techniques unravels the evolution of intrinsic defect density and layer morphology correlated with lattice strain from the early stages of the perovskite deposition.

Published
2024
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12. Pizza Oven Processing of Organohalide Perovskites (POPOP): A Simple, Versatile and Efficient Vapor Deposition Method.

Author

Guesnay, Quentin, Sahli, Florent, Artuk, Kerem, Turkay, Deniz, Kuba, Austin G., Mrkyvkova, Nada, Vegso, Karol, Siffalovic, Peter, Schreiber, Frank, Lai, Huagui, Fu, Fan, Ledinský, Martin, Fürst, Nicolas, Schafflützel, Aymeric, Bucher, Cédric, Jeangros, Quentin, Ballif, Christophe, and Wolff, Christian M.

Subjects
VAPOR-plating, PEROVSKITE, METAL halides, VAPOR pressure, METAL coating, VACUUM chambers
Abstract

Hybrid vapor deposition is one of the most appealing processes for perovskite photovoltaics fabrication, thanks to its versatile nature. By using sequentially different vapor deposition processes tailored to the inorganic and organic perovskite precursors' peculiarities, this type of process gives access to the full potential of vapor deposition. While vapor deposition of metal halides is well understood and mastered, vapor deposition of organohalide species is much more delicate (degradation of vapors, high vapor pressure, setup‐specific constraints). Here, a novel close space sublimation system is reported and in‐depth insights on the conversion into perovskite of a metal halide template are provided. In this evolution of the process, the substrate coated with metal halide template and the organohalide source are loaded together in a dedicated holder, then transferred into a vacuum chamber on a heating element already at temperature setpoint. The system enables a simple, fast, low‐cost, and easy‐to‐reproduce organohalide vapor deposition process. The formation of the perovskite in situ and identification different conversion regimes are studied. Furthermore, the influence of the chemical environment and chamber design on the process are discussed. Compositional tuning and additive engineering in the process are processed and fabricate proof of concept photovoltaic devices reaching high fill factors of 80% and 17% power conversion efficiency for a bandgap of 1.63 eV. [ABSTRACT FROM AUTHOR]

Published
2024
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13. 2D Halide Perovskite Phase Formation Dynamics and Their Regulation by Co‐Additives for Efficient Solar Cells.

Author

Liu, Min, Zheng, Daming, Zhu, Tao, Vegso, Karol, Siffalovic, Peter, and Pauporté, Thierry

Subjects
SOLAR cells, PEROVSKITE, AMMONIUM ions, EMISSION spectroscopy, FOOD additives, HALIDES
Abstract

The incorporation of large organic ammonium ions renders the crystallization dynamics and layer formation process of halide perovskites complex, difficult to control, and leads to problems of suppressed charge transport with the formation of tiny‐sized grains. In this paper, the use of methylammonium chloride (MACl) and an excess of PbI2 is introduced as a co‐additives in the precursor solution for the control of phenylmethylammonium or benzylammonium (PMA+ spacer) and formamidinium (FA+)‐based quasi‐2D PMA2FAn−1PbnI3n+1 (n = 5) perovskite layers formation. By this method, the morphology of the layer, the inner phase distribution, and the charge transport properties are improved. By employing glow discharge‐optical emission spectroscopy (GD‐OES) and other techniques, it is revealed that the quasi‐2D perovskites prepared in the presence of co‐additives exhibit uniform removal dynamics of the solvent across the film. Furthermore, the grain growth mode, upon thermal annealing, is lateral. It results in large, monolithic grains with low‐trap state density and excellent substrate coverage. Particularly, co‐additives improve the cations dispersion upon the crystallization process, thus suppressing the low‐n phase formed through the aggregation of spacer cations and accelerating the formation of the high‐n phase. [ABSTRACT FROM AUTHOR]

Published
2024
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14. Lithium-Induced Reorientation of Few-Layer MoS2 Films

Author

Sojková, Michaela, primary, Píš, Igor, additional, Hrdá, Jana, additional, Vojteková, Tatiana, additional, Pribusová Slušná, Lenka, additional, Vegso, Karol, additional, Siffalovic, Peter, additional, Nadazdy, Peter, additional, Dobročka, Edmund, additional, Krbal, Miloš, additional, Fons, Paul J., additional, Munnik, Frans, additional, Magnano, Elena, additional, Hulman, Martin, additional, and Bondino, Federica, additional

Published
2023
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17. Ordered growth of hexagonal and monoclinic phases of MoTe2 on a sapphire substrate.

Author

Slušná, Lenka Pribusová, Vegso, Karol, Dobročka, Edmund, Vojteková, Tatiana, Nádaηdy, Peter, Halahovets, Yuriy, Sojková, Michaela, Hrdá, Jana, Precner, Marián, Šiffalovič, Peter, Chen, Zhuo, Huang, Yong, Raηnjević, Sergej, Zhang, Zaoli, and Hulman, Martin

Subjects
*SAPPHIRES, *HEXAGONAL crystal system, *TRANSMISSION electron microscopy, *X-ray scattering, *DIFFRACTION patterns, *TRANSITION metals, *THIN films
Abstract

The transition metal dichalcogenides have been studied for various applications in electronics, sensing, or spintronics. Molybdenum ditelluride, MoTe2, occurs in 3 crystal systems: hexagonal (2H), monoclinic (1T′), and orthorhombic (Td). Here we report on tellurisation of Mo and MoO3 thin films to 2H-MoTe2 and 1T′-MoTe2 thin layers on sapphire substrates, respectively. To study the phases, we employed diffraction patterns using grazing-incidence wide-angle X-ray scattering, conventional X-ray diffraction and transmission electron microscopy (TEM). Measurements of pole figures confirmed the presence of a biaxial texture of both 1T′ and 2H phases. In the hexagonal phase, we found two ensembles of biaxially oriented crystallites offset by 30 degrees between the two groups. On the other hand, in the monoclinic layer, the crystallites follow the six-fold symmetry of the (0001) sapphire surface. [ABSTRACT FROM AUTHOR]

Published
2023
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18. High‐Resolution and Stable Ruddlesden–Popper Quasi‐2D Perovskite Flexible Photodetectors Arrays for Potential Applications as Optical Image Sensor.

Author

Wang, Tao, Zheng, Daming, Vegso, Karol, Mrkyvkova, Nada, Siffalovic, Peter, and Pauporté, Thierry

Subjects
OPTICAL sensors, PEROVSKITE, SPECTRAL sensitivity, PHOTODETECTORS, PHOTOELECTRIC devices, IMAGE sensors
Abstract

The development of an efficient fabrication route to achieve high‐resolution perovskite pixel array is key for large‐scale flexible image sensor devices. Herein, a high‐resolution and stable 10 × 10 flexible PDs array based on formamidinium(FA+) and phenylmethylammonium (PMA+) quasi‐2D (PMA)2FAPb2I7 (n = 2) perovskite is demonstrated by developing SiO2‐assisted hydrophobic and hydrophilic treatment process on polyethylene terephthalate substrate. By introducing Au nanoparticles (Au NPs), the perovskite film quality is improved and grain boundaries are reduced. The mechanism by which Au NPs upgrade the photoelectric quality of perovskite is mainly revealed by glow discharge‐optical emission spectroscopy (GD‐OES) and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS). To further improve the photoelectric performance of the devices, a post‐treatment strategy with formamidinium chloride (FACl) is used. The optimized flexible PDs arrays show excellent optoelectronic properties with a high responsivity of 4.7 A W−1, a detectivity of 6.3 × 1012 Jones, and a broad spectral sensitivity. The device also exhibits excellent electrical stability even under severe bending and excellent flexural strength, as well as excellent environmental stability. Finally, the integrated flexible PDs arrays are used as sensor pixels in an imaging system to obtain high‐resolution imaging patterns, demonstrating the imaging capability of the PDs arrays. [ABSTRACT FROM AUTHOR]

Published
2023
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19. Ordered growth of hexagonal and monoclinic phases of MoTe2 on a sapphire substrate

Author

Slušná, Lenka Pribusová, primary, Vegso, Karol, additional, Dobročka, Edmund, additional, Vojteková, Tatiana, additional, Nádaždy, Peter, additional, Halahovets, Yuriy, additional, Sojková, Michaela, additional, Hrdá, Jana, additional, Precner, Marián, additional, Šiffalovič, Peter, additional, Chen, Zhuo, additional, Huang, Yong, additional, Ražnjević, Sergej, additional, Zhang, Zaoli, additional, and Hulman, Martin, additional

Published
2023
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22. Lithium-Induced Reorientation of Few-Layer MoS2 Films.

Author

Sojková, Michaela, Píš, Igor, Hrdá, Jana, Vojteková, Tatiana, Pribusová Slušná, Lenka, Vegso, Karol, Siffalovic, Peter, Nadazdy, Peter, Dobročka, Edmund, Krbal, Miloš, Fons, Paul J., Munnik, Frans, Magnano, Elena, Hulman, Martin, and Bondino, Federica

Published
2023
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24. Monolithic Perovskite/Silicon Tandems with >28% Efficiency: Role of Silicon‐Surface Texture on Perovskite Properties

Author

De Bastiani, Michele, primary, Jalmood, Rawan, additional, Liu, Jiang, additional, Ossig, Christina, additional, Vlk, Aleš, additional, Vegso, Karol, additional, Babics, Maxime, additional, Isikgor, Furkan H., additional, Selvin, Anand S., additional, Azmi, Randi, additional, Ugur, Esma, additional, Banerjee, Swarnendu, additional, Mirabelli, Alessandro J., additional, Aydin, Erkan, additional, Allen, Thomas G., additional, Ur Rehman, Atteq, additional, Van Kerschaver, Emmanuel, additional, Siffalovic, Peter, additional, Stuckelberger, Michael E., additional, Ledinsky, Martin, additional, and De Wolf, Stefaan, additional

Published
2022
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25. Aligned Bilayer of Single-Walled Carbon Nanotubes Suppresses the Polysulfide Shuttle in Li–S Batteries

Author

Ashraf, Muhammad Adeel, primary, Vegso, Karol, additional, Shaji, Ashin, additional, Bodik, Michal, additional, Sánchez, Mayela García, additional, Zubair, Muhammad, additional, Din, Muhammad Faraz Ud, additional, Majkova, Eva, additional, Fedorková, Andrea Straková, additional, Keckes, Jozef, additional, and Siffalovic, Peter, additional

Published
2022
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26. A wide-angle X-ray scattering laboratory setup for tracking phase changes of thin films in a chemical vapor deposition chamber

Author

Vegso, Karol, primary, Shaji, Ashin, additional, Sojková, Michaela, additional, Slušná, Lenka Príbusová, additional, Vojteková, Tatiana, additional, Hrdá, Jana, additional, Halahovets, Yuriy, additional, Hulman, Martin, additional, Jergel, Matej, additional, Majková, Eva, additional, Wiesmann, Jörg, additional, and Šiffalovič, Peter, additional

Published
2022
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29. Monolithic Perovskite/Silicon Tandems with >28% Efficiency: Role of Silicon‐Surface Texture on Perovskite Properties.

Author

De Bastiani, Michele, Jalmood, Rawan, Liu, Jiang, Ossig, Christina, Vlk, Aleš, Vegso, Karol, Babics, Maxime, Isikgor, Furkan H., Selvin, Anand S., Azmi, Randi, Ugur, Esma, Banerjee, Swarnendu, Mirabelli, Alessandro J., Aydin, Erkan, Allen, Thomas G., Ur Rehman, Atteq, Van Kerschaver, Emmanuel, Siffalovic, Peter, Stuckelberger, Michael E., and Ledinsky, Martin

Subjects
PHOTOVOLTAIC power systems, SILICON solar cells, SOLAR cell manufacturing, PEROVSKITE, SILICON wafers, SILICON surfaces, OPTICAL spectroscopy
Abstract

Textured silicon wafers used in silicon solar cell manufacturing offer superior light trapping, which is a critical enabler for high‐performance photovoltaics. A similar optical benefit can be obtained in monolithic perovskite/silicon tandem solar cells, enhancing the current output of the silicon bottom cell. Yet, such complex silicon surfaces may affect the structural and optoelectronic properties of the overlying perovskite films. Here, through extensive characterization based on optical and microstructural spectroscopy, it is found that the main effect of such substrate morphology lies in an altering of the photoluminescence response of the perovskite, which is associated with thickness variations of the perovskite, rather than lattice strain or compositional changes. With this understanding, the design of high‐performance perovskite/silicon tandems is rationalized, yielding certified power conversion efficiencies of >28%. [ABSTRACT FROM AUTHOR]

Published
2023
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31. Growth of PtSe2 few-layer films on NbN superconducting substrate

Author

Sojková, Michaela, primary, Hrdá, Jana, additional, Volkov, Serhii, additional, Vegso, Karol, additional, Shaji, Ashin, additional, Vojteková, Tatiana, additional, Slušná, Lenka Pribusová, additional, Gál, Norbert, additional, Dobročka, Edmund, additional, Siffalovic, Peter, additional, Roch, Tomáš, additional, Gregor, Maroš, additional, and Hulman, Martin, additional

Published
2021
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32. Structural and Trap‐State Density Enhancement in Flash Infrared Annealed Perovskite Layers

Author

Brunova, Alica, primary, Vegso, Karol, additional, Nadazdy, Vojtech, additional, Nadazdy, Peter, additional, Subair, Riyas, additional, Jergel, Matej, additional, Majkova, Eva, additional, Pandit, Pallavi, additional, Roth, Stephan V., additional, Krasnansky, Alexander, additional, Hinderhofer, Alexander, additional, Schreiber, Frank, additional, Tian, Jianjun, additional, and Siffalovic, Peter, additional

Published
2021
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33. Orientation of Few-Layer MoS2 Films: In-Situ X-ray Scattering Study During Sulfurization

Author

Shaji, Ashin, primary, Vegso, Karol, additional, Sojkova, Michaela, additional, Hulman, Martin, additional, Nadazdy, Peter, additional, Hutar, Peter, additional, Pribusova Slusna, Lenka, additional, Hrda, Jana, additional, Bodik, Michal, additional, Hodas, Martin, additional, Bernstorff, Sigrid, additional, Jergel, Matej, additional, Majkova, Eva, additional, Schreiber, Frank, additional, and Siffalovic, Peter, additional

Published
2021
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35. Mesoporous SnO2 Nanoparticle-Based Electron Transport Layer for Perovskite Solar Cells.

Author

Ullah, Sami, Din, Muhammad Faraz Ud, Khan Kasi, Jafar, Khan Kasi, Ajab, Vegso, Karol, Kotlar, Mario, Micusik, Matej, Jergel, Matej, Nadazdy, Vojtech, Siffalovic, Peter, Majkova, Eva, and Fakharuddin, Azhar

Abstract

A perovskite solar cell (PSC) featuring a mesoporous architecture can facilitate perovskite layer formation over a large area via increasing the number of heterogeneous nucleation sites. The morphology of the electron transport layer (ETL) and its interface with the perovskite layer is one of the key factors to boost the performance of a PSC. Tin dioxide (SnO2) is considered as a promising ETL in PSCs owing to its high carrier mobility, good transmittance, deep conduction band level, and efficient photoelectron extraction. Generally, the mesoporous SnO2 (m-SnO2) ETL has a higher surface-to-volume ratio compared to a compact SnO2 layer. Herein, we report on an m-SnO2 ETL prepared by anodizing a metallic tin film on a fluorine-doped tin oxide (FTO) substrate in NaOH solution under an ambient atmosphere. In particular, we developed a bilayer architecture of the m-SnO2 ETL based on the fabrication of two consecutive m-SnO2 layers. The morphology of each layer was controlled by varying the anodization voltage and time at a constant solution concentration during the growth process. This unique approach enabled the deposition of an m-SnO2 ETL with sufficient coverage of the FTO substrate, which is difficult to achieve with a single layer of m-SnO2. In particular, the scanning electron and atomic force microscopy analyses confirmed that the m-SnO2 layer covers completely the FTO substrate. The device fabricated with this bilayer m-SnO2 ETL achieved a 27% improvement in power conversion efficiency compared to that with a single layer of m-SnO2. [ABSTRACT FROM AUTHOR]

Published
2022
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36. Crystallization of 2D Hybrid Organic–Inorganic Perovskites Templated by Conductive Substrates

Author

Kovaricek, Petr, primary, Nadazdy, Peter, additional, Pluharova, Eva, additional, Brunova, Alica, additional, Subair, Riyas, additional, Vegso, Karol, additional, Guerra, Valentino Libero Pio, additional, Volochanskyi, Oleksandr, additional, Kalbac, Martin, additional, Krasnansky, Alexander, additional, Pandit, Pallavi, additional, Roth, Stephan Volker, additional, Hinderhofer, Alexander, additional, Majkova, Eva, additional, Jergel, Matej, additional, Tian, Jianjun, additional, Schreiber, Frank, additional, and Siffalovic, Peter, additional

Published
2021
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39. Highly Crystalline MoS 2 Thin Films Fabricated by Sulfurization

Author

Hutar, Peter, primary, Spankova, Marianna, additional, Sojkova, Michaela, additional, Dobrocka, Edmund, additional, Vegso, Karol, additional, Hagara, Jakub, additional, Halahovets, Yuriy, additional, Majkova, Eva, additional, Siffalovic, Peter, additional, and Hulman, Martin, additional

Published
2019
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41. Tailored Langmuir–Schaefer Deposition of Few-Layer MoS2 Nanosheet Films for Electronic Applications

Author

Kalosi, Anna, primary, Demydenko, Maksym, additional, Bodik, Michal, additional, Hagara, Jakub, additional, Kotlar, Mario, additional, Kostiuk, Dmytro, additional, Halahovets, Yuriy, additional, Vegso, Karol, additional, Marin Roldan, Alicia, additional, Maurya, Gulab Singh, additional, Angus, Michal, additional, Veis, Pavel, additional, Jergel, Matej, additional, Majkova, Eva, additional, and Siffalovic, Peter, additional

Published
2019
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42. Polyethylene Glycol-Modified Poly(Styrene-co-Ethylene/Butylene-co-Styrene)/Carbon Nanotubes Composite for Humidity Sensing

Author

Mičušík, Matej, primary, Chatzimanolis, Christos, additional, Tabačiarová, Jana, additional, Kollár, Jozef, additional, Kyritsis, Apostolos, additional, Pissis, Polycarpos, additional, Pionteck, Jürgen, additional, Vegso, Karol, additional, Siffalovic, Peter, additional, Majkova, Eva, additional, and Omastová, Mária, additional

Published
2019
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43. Tuning the orientation of few-layer MoS2 films using one-zone sulfurization

Author

Sojková, Michaela, primary, Vegso, Karol, additional, Mrkyvkova, Nada, additional, Hagara, Jakub, additional, Hutár, Peter, additional, Rosová, Alica, additional, Čaplovičová, Mária, additional, Ludacka, Ursula, additional, Skákalová, Viera, additional, Majková, Eva, additional, Siffalovic, Peter, additional, and Hulman, Martin, additional

Published
2019
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44. Orientation of Few-Layer MoS2Films: In-Situ X-ray Scattering Study During Sulfurization

Author

Shaji, Ashin, Vegso, Karol, Sojkova, Michaela, Hulman, Martin, Nadazdy, Peter, Hutar, Peter, Pribusova Slusna, Lenka, Hrda, Jana, Bodik, Michal, Hodas, Martin, Bernstorff, Sigrid, Jergel, Matej, Majkova, Eva, Schreiber, Frank, and Siffalovic, Peter

Abstract

Some of the distinct optical, catalytical, and electronic properties of few-layer MoS2films arise from a specific orientation of the MoS2layers. The growth of horizontally or vertically aligned MoS2during the sulfurization of predeposited Mo film can be controlled by various physical conditions such as temperature, heating rate, Mo film thickness, or sulfur vapor pressure. However, due to the inherent limitations of performing real-time and in situexperiments during sulfurization in a standard growth chamber, only a limited number of analytical techniques can be used to elucidate the in-process phase transformation. Here, we present a comprehensive real-time study of the growth of few-layer MoS2films by sulfurization of Mo films using in situgrazing-incidence wide-angle X-ray scattering. We demonstrate that the process gas flow, and thus the sulfur partial vapor pressure, is the key control parameter for the few-layer MoS2layer orientation while all other process parameters remain fixed. Tracking the crystallization of few-layer MoS2layers in real-time allowed us to estimate the activation energy required for both horizontal and vertical orientations. Growth of either horizontal or vertical MoS2was observed without a metastable transition between them throughout the sulfurization.

Published
2021
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