Pokročilé nízkodimenzionální nanomateriály

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    Coverage Contact Control of Benzoxazole-Based SAMs to Enhance the Operational Performance of Perovskite Nanocrystal Light-Emitting Diodes
    (2025-05-01) Villanueva-Antoli, Alexis; Marín-Moncusí, Laia; Puerto-Galvis, Carlos E.; Sánchez, Rafael S.; Simancas, Jorge; Barea, Eva Maria; Rodriguez Pereira, Jhonatan; Pareja-Rivera, Carina; Gualdron-Reyes, Andres F.; Palomares, Emilio; Martínez-Ferrero, Eugenia; Mora-Sero, Ivan
    Perovskite light-emitting diodes (PeLEDs) have emerged as a prominent topic within optoelectronic research. Despite remarkable advancements, this technology still faces challenges that must be addressed for successful commercialization. Typical device architectures employ PEDOT:PSS as hole transporting material (HTM). However, besides its expensive cost, PEDOT:PSS has been reported to cause issues with efficiency and long-term stability. Molecular self-assembled monolayers (SAMs) have arisen as potential HTMs, not just to overcome these drawbacks but to enhance the interface properties and performance of LEDs. This technology has been efficiently applied in PeLEDs, but its use in devices based on perovskite nanocrystals (PNCs) remain underexplored. In this work, two benzoxazole derivatives have been analyzed as SAMs to conform the hole selective contact in CsPbBr3 PNCs-based LEDs. The devices demonstrate improved optoelectronic properties compared to the reference composed of PEDOT:PSS, attributed to a suitable band alignment and an enhanced charge injection. Furthermore, optimizing the deposition technique of SAMs on the conducting substrate by dip- or spin-coating has allowed the preparation of efficient LEDs exhibiting external quantum efficiencies (EQEs) up to 6.8% with 300 s of operational stability. This research aims to provide extensive insights into applying SAMs to design PeLEDs with improved carrier mobility.
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    Structural and Optical Properties of Luminescent Copper(I) Chloride Thin Films Deposited by Sequentially Pulsed Chemical Vapour Deposition
    (MDPI, 2018-10-01) Krumpolec, Richard; Homola, Tomáš; Cameron, David Campbell; Humlíček, Josef; Caha, Ondřej; Kuldová, Karla; Zazpe Mendioroz, Raúl; Přikryl, Jan; Macák, Jan
    Sequentially pulsed chemical vapour deposition was used to successfully deposit thin nanocrystalline films of copper(I) chloride using an atomic layer deposition system in order to investigate their application to UV optoelectronics. The films were deposited at 125 degrees C using [Bis(trimethylsilyl)acetylene](hexafluoroacetylacetonato)copper(I) as a Cu precursor and pyridine hydrochloride as a new Cl precursor. The films were analysed by XRD, X-ray photoelectron spectroscopy (XPS), SEM, photoluminescence, and spectroscopic reflectance. Capping layers of aluminium oxide were deposited in situ by ALD (atomic layer deposition) to avoid environmental degradation. The film adopted a polycrystalline zinc blende-structure. The main contaminants were found to be organic materials from the precursor. Photoluminescence showed the characteristic free and bound exciton emissions from CuCl and the characteristic exciton absorption peaks could also be detected by reflectance measurements.
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    Intrinsic properties of high -aspect ratio single- and double -wall anodic TiO 2 nanotube layers annealed at different temperatures
    (Elsevier, 2020-08-20) Motola, Martin; Hromádko, Luděk; Přikryl, Jan; Sopha, Hanna Ingrid; Krbal, Miloš; Macák, Jan
    TiO2 nanotube layers of different thicknesses and tube wall morphologies exploited. Single-wall nanotubes were obtained by chemical etching of double-wall ones. Photocurrents, structure, optical and electronic properties of tubes were compared.
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    Anodization of electrodeposited titanium films towards TiO2 nanotube layers
    (Elsevier, 2020-09-01) Sopha, Hanna Ingrid; Norikawa, Yutaro; Motola, Martin; Hromádko, Luděk; Rodriguez Pereira, Jhonatan; Černý, Jiří; Nohira, Toshiyuki; Yasuda, Kouji; Macák, Jan
    Ti films electrodeposited on Ni foils from molten salts were anodized towards TiO2 nanotube formation for the first time. The resulting TiO2 nanotube (TNT) layers were compared with TNT layers prepared under identical conditions on Ti foils by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) measurements, X-ray photoelectron spectroscopy (XPS), and photocurrent measurements. No significant differences were found between the TNT layers prepared on the two different substrates. Electrodeposited Ti films prepared in this way could thus be a viable option for anodization purposes.
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    Fabrication of TiO2 nanotubes on Ti spheres using bipolar electrochemistry
    (Elsevier, 2020-02-01) Sopha, Hanna Ingrid; Hromádko, Luděk; Motola, Martin; Macák, Jan
    In this work, the anodization of Ti spheres using bipolar electrochemistry is reported for the first time. TiO2 nanotubes were found over the entire surface area of the Ti spheres when a square-wave potential was employed. The TiO2 nanotubes were similar to 77 nm in inner diameter and had a thickness of similar to 2 mu m on the extremities of the Ti spheres. Due to their increased surface area, the Ti spheres covered with TiO2 nanotubes had a rate constant for the photocatalytic degradation of methylene blue which was approximately 2.15 times higher than that of non-anodized Ti spheres with a thin thermal oxide layer.