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Author: Ahmad, Ahmad A. × End date: 2022 × Start date: 2022 × Version: publishedVersion × WGL Institute: ISAS ×

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    E/Z reversible photoisomerization of methyl orange doped polyacrylic acid-based polyelectrolyte brush films
    (Hoboken, NJ [u.a.] : Wiley InterScience, 2022) Al‐Bataineh, Qais M.; Telfah, Ahmad D.; Ahmad, Ahmad A.; Bani‐Salameh, Areen A.; Abu‐Zurayk, Rund; Hergenröder, Roland
    The photoswitching behavior of the polyacrylic acid (PAA) doped by methyl orange (MO) brush film was investigated using spectral analysis of UV-Vis absorbance, Fourier Transformation Infrared spectroscopy, 2D electrical conductivity mapping and Atomic Force Microscopy. The kinetics and time evolution of the photoisomerization of the PAA-MO PEBs film from E-state to Z-state by UV-light irradiation, and reverse thermal relaxation to E-state was explored. The results confirm that the photoisomerization kinetics of the overall peak is the superposition of the photoisomerization kinetics of (Formula presented.) transition, low- and high-frequency of the (Formula presented.) transition bands. The E–Z transformation led to transforming the azobenzene from flat with no dipole moment to 3.0 D dipole moment. Hence, the electrical conductivity escalated accordingly. The transformation of E-state to Z-state led to the collapse of the formed brushes because of the angular rotational momentum consequent to E–Z isomerization.
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    Optical, electrical and chemical properties of PEO:I2 complex composite films
    (Heidelberg [u.a.] : Springer, 2022) Telfah, Ahmad; Al-Bataineh, Qais M.; Tolstik, Elen; Ahmad, Ahmad A.; Alsaad, Ahmad M.; Ababneh, Riad; Tavares, Carlos J.; Hergenröder, Roland
    Synthesized PEO:I2 complex composite films with different I2 concentrations were deposited onto fused silica substrates using a dip-coating method. Incorporation of PEO films with I2 increases the electrical conductivity of the composite, reaching a maximum of 46 mS/cm for 7 wt% I2. The optical and optoelectronic properties of the complex composite films were studied using the transmittance and reflectance spectra in the UV-Vis region. The transmittance of PEO decreases with increasing I2 content. From this study, the optical bandgap energy decreases from 4.42 to 3.28 eV as I2 content increases from 0 to 7 wt%. In addition, the refractive index for PEO films are in the range of 1.66 and 2.00.1H NMR spectra of pure PEO film shows two major peaks at 3.224 ppm and 1.038 ppm, with different widths assigned to the mobile polymer chains in the amorphous phase, whereas the broad component is assigned to the more rigid molecules in the crystalline phase, respectively. By adding I2 to the PEO, both peaks (amorphous and crystal) are shifted to lower NMR frequencies indicating that I2 is acting as a Lewis acid, and PEO is acting as Lewis base. Hence, molecular iodine reacts favorably with PEO molecules through a charge transfer mechanism, and the formation of triiodide (I3-), the iodite (IO2-) anion, I 2· · · PEO and I2+···PEO complexes. PEO:I2 complex composite films are expected to be suitable for optical, electrical, and optoelectronic applications.
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    Hidden impurities in transparent conducting oxides: study of vacancies-related defects and impurities in (Cu–Ni) co-doped ZnO films
    (Heidelberg [u.a.] : Springer, 2022) Al-Bataineh, Qais M.; Ahmad, Ahmad A.; Aljarrah, Ihsan A.; Alsaad, Ahmad M.; Telfah, Ahmad
    The effect of hydrogen and nitrogen impurities on the physical properties of transparent conductive oxides is investigated in this study. Therefore, 5 wt.% of copper and 5 wt.% of nickel co-doped zinc oxide ((Cu–Ni)/ZnO) films were prepared using the sol–gel method. The (Cu–Ni)/ZnO films were annealed in an oven at 500 °C for 2 h under air, vacuum, nitrogen, and argon atmospheres. The synthesized zinc hydroxide film was transformed to zinc oxide film during the annealing by evaporating H 2O. Films annealed under the mentioned atmosphere including as-prepared one were characterized by analyzing with UV–Vis and FTIR spectra in addition to the 2D mapping electrical conductivity of the surface measured by the 4-point probe. The annealed films under air, vacuum, and argon atmospheres led to generate H-related impurities bounded to the oxygen vacancy (H O) which they act as shallow donor defects resulting in forming (Cu–Ni)/ZnO films into n-type materials. Whereas, the film annealed under a nitrogen atmosphere has N-related defects bounding to the zinc vacancy (N Zn) which they act as shallow acceptor defects resulting in transforming the film from n-type to p-type. These defects affect the optical, electrical, and optoelectronic properties of the (Cu–Ni)/ZnO films.