Large refractive index changes in ZIF-8 thin films of optical quality

Keppler, Nils; Hindricks, Karen D. J.; Behrens, Peter

doi:10.1039/d1ra08531j

Cited by 39 publications

(44 citation statements)

References 54 publications

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“…Krypton physisorption measurements show that the thin films are porous after only one deposition cycle, as shown below (Section ). The total uptake and the BET area both increase with the number of deposition cycles, as we have shown before . SEM images of the films after one and two deposition cycles are given in the Supporting Information (Figure S2).…”

Section: Resultssupporting

confidence: 67%

“…Also, additional deposits of foreign substances (either within the film or on its surface) can act as scattering centers, although the refractive index difference is smaller then. With regard to thin films of MOFs, we expect in addition that they feature an addressable porosity which may, for example, be used in sensors , or to manipulate the refractive index. , Preferably, the films should be crystalline, with the defined structure enhancing, for example, the selectivity in sensing.…”

Section: Resultsmentioning

confidence: 99%

“…41,51 Dense thin films which are fabricated directly from the precursor solution show a much higher quality. 35,48,49 In the present work, we have therefore concentrated on the promising cycle-based direct growth procedure, which had been reported for the growth of ZIF-8 thin films of optical quality before. 35,49 Here, we extend this work to prepare MOFon-MOF systems where the high-quality ZIF-8 coating is used as a seeding layer for the growth of thin films of Co-ZIF-90.…”

Section: Introductionmentioning

confidence: 99%

“…35,48,49 In the present work, we have therefore concentrated on the promising cycle-based direct growth procedure, which had been reported for the growth of ZIF-8 thin films of optical quality before. 35,49 Here, we extend this work to prepare MOFon-MOF systems where the high-quality ZIF-8 coating is used as a seeding layer for the growth of thin films of Co-ZIF-90. ZIF-8 and ZIF-90 both crystallize in the sod topology, as do a variety of other ZIFs.…”

Section: Introductionmentioning

confidence: 99%

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Seeding Layer Approach for the Synthesis of Co-ZIF-90 Thin Films of Optical Quality

Keppler

Fricke

Schaate

et al. 2022

Crystal Growth & Design

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The growth of zeolitic imidazolate framework (ZIF) thin films is an interesting topic, since ZIFs have a high thermal and chemical stability compared to many other MOFs. A variety of functionalities can be introduced via the imidazole linker molecule. Here, we report on a new approach for the preparation of thin films of a novel ZIF material: Co-ZIF-90. The preparation of thin films is possible on silicon or glass when ZIF-8 seeding layers are deposited first. The resulting constructions are effectively MOF-on-MOF layer systems. The synthesis procedure has been optimized with regard to obtaining high-quality thin films of Co-ZIF-90 on ZIF-8 for optical applications. Notably, the preparation of Co-ZIF-90 thin films is possible only by using a mixture of two different cobalt precursor salts (acetate and nitrate). The thin films are characterized in detail. With regard to the use as an optical material, UV−vis absorption spectra of the MOF-on-MOF constructs were measured and the refractive index of Co-ZIF-90 was determined using ellipsometry. Furthermore, the refractive index of the Co-ZIF-90 film can be modulated reversibly by the adsorption and desorption of water via the gas phase. The kinetics of this fast process are on the time scale of 1 s. In addition to the preparation of thin films, we obtained Co-ZIF-90 as a powder sample and basically characterized the powder. The approach to use an easy-to-crystallize ZIF-8 film as a seeding layer for the growth of films of other ZIFs may be extended as a general concept for the deposition of crystalline ZIF layers in such cases, where a direct deposition is difficult or not possible.

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Section: Resultssupporting

confidence: 67%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seeding Layer Approach for the Synthesis of Co-ZIF-90 Thin Films of Optical Quality

Keppler

Fricke

Schaate

et al. 2022

Crystal Growth & Design

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“…[22][23][24] The MOF nanotechnology provides more opportunities for the development of new OFSs, 25,26 in particular, for VOC sensing. 27 The interaction of MOF material with VOC molecules can lead to a signicant change in the refractive index of the material, [28][29][30] which allows VOC to be sensitively detected in OFSs. Optical ber Fabry-Perot cavities integrated with ZIF-8, HKUST-1, and Uio-66 for the detection of VOC, explosive, and carbon dioxide, as well as rhodamine-B in aqueous solutions, have been reported.…”

Section: Introductionmentioning

confidence: 99%

Engineering of metal–organic framework nanomaterials on long-period fiber grating for acetone vapor sensing

et al. 2022

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Grayscale to Multicolor Laser Writing Inside a Label‐Free Metal‐Organic Frameworks

Zhestkij,

Efimova,

Kenzhebayeva

et al. 2024

Adv Funct Materials

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Direct laser writing (DLW), being a universal tool for fast creating colorless/color images on different substrates, still suffers from simultaneous writing grayscale and color images inside the transparent media. Here, it is discovered that a unique set of porosity, coordination bonding between organic and inorganic building blocks, and the lack of inversion symmetry of the label‐free metal‐organic frameworks (MOFs), on the one hand, provides the possibility of laser writing the grayscale images through the amorphization/carbonization. On the other hand, the reduction of the laser writing power leads to controllable creation of color images via defect formation with sub‐diffraction resolution inside the MOF crystals. The latter is due to the processes of self‐absorption of generated optical harmonics by nonlinear MOFs within the visible spectral range. As a result, simultaneous grayscale and multicolor writing of QR codes and images are demonstrated with up to 400 nm resolution inside optically transparent MOF crystals, thereby discovering a new family of functional materials for DLW.

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Large refractive index changes in ZIF-8 thin films of optical quality

Abstract: The refractive index (RI) of ZIF-8 thin films with optical quality was determined over the whole visible spectrum. The RI can be fine-tuned over a wide range by loading with different organic guest molecules for various optical applications.

Cited by 39 publications

References 54 publications

Seeding Layer Approach for the Synthesis of Co-ZIF-90 Thin Films of Optical Quality

Seeding Layer Approach for the Synthesis of Co-ZIF-90 Thin Films of Optical Quality

Engineering of metal–organic framework nanomaterials on long-period fiber grating for acetone vapor sensing

Grayscale to Multicolor Laser Writing Inside a Label‐Free Metal‐Organic Frameworks

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