Πλοήγηση ανά Συγγραφέας "Gkikas, Ioannis"

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    Lattice dynamics of hybrid halide perovskite single crystals by dielectric spectroscopy
    (ΕΛΜΕΠΑ, Σχολή Μηχανικών (ΣΜΗΧ), ΔΠΜΣ Νανοτεχνολογία για Ενεργειακές Εφαρμογές, 2026-04-02) Gkikas, Ioannis; Γκίκας, Ιωάννης; Lappas, Alexandros; Stoumpos, Konstantinos; Λάππας, Αλέξανδρος; Στούμπος, Κωνσταντίνος
    Halide perovskites AMX3 (A+ = Cs, CH3NH3 or HC(NH2)2 , M2+ = Pb, Sn or Ge and X- = Cl, Br or I), are amongst the leading emerging materials in the past decade towards optoelectronic and environmental remediation applications, including devices such as solar cells, light-emitting diodes, hard radiation detectors and photocatalytic modules. What makes these semiconductor materials so attractive for optoelectronic devices is their superb absorption across the visible and near-infrared region (Eg = 1.1-3.0 eV) and their high charge-carrier mobility and long charge-carrier diffusion lengths. An important research branch of halide perovskites focuses in the understanding of the underlying physicochemical origins of these fascinating properties, which is currently lacking. Such understanding will be beneficial not only from the fundamental science perspective but also crucial for the rational enhancement of the optoelectronic performance. In this work, mm-sized single-crystals of hybrid halide perovskites were grown (MAPbCl3 and MAPbBr3) and studied. Structurally and spectroscopically using a custom made set up, with capabilities to investigate the lattice dynamic of the crystalline material, and correlate the phase transition transformation to the dielectric properties. Also, relaxation time mechanisms were studied compering different models and proving the optional as the Havriliak-Negami. Calculated the relaxation time and the exponents of the fitting model, providing information of the dipole behavior.