Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği

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Access Right: Closed AccessPublisher: search.filters.publisher.American Chemical Society

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  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Enhancement of the Spontaneous Emission Rate of Perovskite Nanowires Coupled Into Cylindrical Hollow Nanocavities Formed on the Surface of Polystyrene Microfibers
    (American Chemical Society, 2019) Gökbulut, Belkis; İnanç, Arda; Demir, Mustafa Muammer; Güner, Tuğrul; Demir, Mustafa Muammer; İnci, M. Naci; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of Technology
    Fluorescent CsPbBr3 nanowires are uniformly integrated into a porous polystyrene matrix in the form of microfibers to investigate the changes in their spontaneous emission rate. Cylindrical hollow nanocavities, ranging from 75 to 160 nm in diameter, are grown on the surface of the polymer microfibers during the fabrication process, which allow coupling light that is emitted from the excited CsPbBr3 nanowires. Time-resolved experiments elucidate that the spontaneous emission rate of the perovskite nanowires is observed to increase by a factor of 4.9, upon coupling of the excited optical modes into the nanocavities, which is demonstrated to be in good agreement with our theoretical calculations.
  • Article
    Citation - WoS: 72
    Citation - Scopus: 77
    Gd3+-Doped Alpha-Cspbi3 Nanocrystals With Better Phase Stability and Optical Properties
    (American Chemical Society, 2019) Güvenç, Çetin Meriç; Şahin, Hasan; Yalçınkaya, Yenal; Demir, Mustafa Muammer; Özen, Sercan; Şahin, Hasan; Demir, Mustafa Muammer; 04.04. Department of Photonics; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    Black alpha-CsPbI3 perovskites are unable to maintain their phase stability under room conditions; hence, the alpha-CsPbI3 phase transforms into a thermodynamically stable yellow delta-CsPbI3 phase within a few days, which has a nonperovskite structure and high band gap for optoelectronic applications. This phase transformation should be prevented or at least retarded to make use of superior properties of alpha-CsPbI3 in optoelectronic applications. In this study, Gd3+ doping was employed with the aim of increasing the stability of alpha-CsPbI3. All doped alpha-CsPbI3 nanocrystals with various levels of Gd3+, between 5 and 15 mol %, have shown greater phase stability than that of the pure alpha-CsPbI3 phase from 5 days up to 11 days under ambient conditions. This prolonged phase stability can be attributed to three potential reasons: increased tolerance factor of the perovskite structure, distorted cubic symmetry, and decreased defect density in nanocrystals. Urbach energy values suggest the reduction of defect density in the doped nanocrystals. Also, use of 10 mol % Gd3+ as a dopant material increases the photoluminescence quantum yield from 70 to 80% and fluorescence lifetime of alpha-CsPbI3 from 47.4 to 64.4 ns. Further, density functional theory calculations are in a good agreement with the experimental results.