Photonics / Fotonik

Permanent URI for this collectionhttps://hdl.handle.net/11147/2590

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Department: search.filters.department.İzmir Institute of Technology. Materials Science and EngineeringPublisher: search.filters.publisher.American Institute of Physics

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  • Article
    Citation - WoS: 3
    Citation - Scopus: 4
    Experimental and First-Principles Investigation of Cr-Driven Color Change in Cesium Lead Halide Perovskites
    (American Institute of Physics, 2019) Özen, Sercan; Şahin, Hasan; Güner, Tuğrul; Demir, Mustafa Muammer; Topçu, Gökhan; Özcan, Mehmet; Demir, Mustafa Muammer; Şahin, Hasan; 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
    Herein, we report room temperature Cr-doping for all-inorganic perovskites that have attracted great attention in recent years due to their extraordinary optical properties, low cost, and ease of synthesis. Incorporation of Cr 3 + ions into the perovskite crystal lattices is achieved by following a facile route involving an antisolvent recrystallization method at room temperature. It is shown that both Cr-doping and formation of crystals in the CsPbBr x Cl 3 - x phase are provided by increasing the concentration of the CrCl 3 solution. It is also observed that the doping procedure leads to the emergence of three types of distinctive peaks in the PL spectrum originating from CsPbBr x Cl 3 - x domains (476-427nm), Cr-strained host lattices (515nm), and midgap states formed by Cr dopants (675-775nm). It is also found that the Cr-doped perovskites emitting a dark violaceous color change their color to white with a high color rendering index (88) in 30-day time intervals. Easy-tunable optical properties of all-inorganic Cs perovskites indicate their great potential for future optoelectronic device applications.
  • Article
    Citation - WoS: 20
    Citation - Scopus: 21
    Monitoring the Effect of Asymmetrical Vertical Strain on Janus Single Layers of Mosse Via Vibrational Spectrum
    (American Institute of Physics, 2018) Kandemir, Ali; Peeters, François M.; Şahin, Hasan; 04.04. Department of Photonics; 04. Faculty of Science; 01. Izmir Institute of Technology
    Using first principles calculations, we study the structural and phononic properties of the recently synthesized Janus type single layers of molybdenum dichalcogenides. The Janus MoSSe single layer possesses 2H crystal structure with two different chalcogenide sides that lead to out-of-plane anisotropy. By virtue of the asymmetric structure of the ultra-thin Janus type crystal, we induced the out-of-plane anisotropy to show the distinctive vertical pressure effect on the vibrational properties of the Janus material. It is proposed that for the corresponding Raman active optical mode of the Janus structure, the phase modulation and the magnitude ratio of the strained atom and its first neighbor atom adjust the distinctive change in the eigen-frequencies and Raman activity. Moreover, a strong variation in the Raman activity of the Janus structure is obtained under bivertical and univertical strains. Not only eigen-frequency shifts but also Raman activities of the optical modes of the Janus structure exhibit distinguishable features. This study reveals that the vertical anisotropic feature of the Janus structure under Raman measurement allows us to distinguish which side of the Janus crystal interacts with the externals (substrate, functional adlayers, or dopants).