Yazar "Cadirci, Musa" seçeneğine göre listele

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    Designing CuInSe2 quantum dot-based high-performance Schottky photodetector: a numerical study
    (Iop Publishing Ltd, 2023) Cadirci, Musa; Yildiz, Murat
    Sensing in the near-infrared and visible wavelengths is critically essential for a broad range of potential applications. Colloidal quantum dot(CQD) based photodetectors provide key advantages, such as spectral tuneability, straight integration with electronic parts, high sensitivity and low cost. Here, a Schottky photodiode architecture based on CuInSe2 (CISe) CQDs structure was designed and its photoresponse characteristics were simulated at various absorber layer thicknesses, at different back contact materials, varying light intensities, several defect densities, and different temperatures. A maximum responsivity of about 0.37 A W-1 was recorded from the proposed device. This work demonstrates that CISe CQDs are potential candidate materials for high-performance Schottky photodetectors operating in the near-infrared and visible electromagnetic spectrum.
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    Dielectric properties of CdSe quantum dots-loaded cryogel for potential future electronic applications
    (Elsevier Sci Ltd, 2020) Cadirci, Musa; Sarkaya, Koray; Alli, Abdulkadir
    Cryogels are an outstanding class of materials with special and functionalized physical properties in various fields and privileges for different industrial applications. Due to unique properties of quantum dots, properties of cryogels can be engineered by adding quantum dots in. In this study, both p(HEMA)-based cryogel and CdSe QDs synthesized and characterized, separately. Then, CdSe QDs were loaded into p(HEMA) cryogels by immersing cryogel into QDs solutions. FTIR-ATR, SEM and TGA characterizations were performed to ensure that CdSe QDs penetrate p(HEMA) cryogels effectively. Dielectric properties of CdSe QDs-loaded cryogel were investigated using Electrical Impedance Spectroscopy (EIS). Real and imaginary parts of dielectric constants were decreased significantly at low frequencies in QD-loaded cryogels. While real part of impedance was increased in CdSe QDs-loaded cryogel at low frequencies. In addition, at high frequencies, those parameters were observed to be same in both cases.
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    Investigating the effect of Zn doping and temperature on the photoluminescence behaviour of CuLaSe2 quantum dots
    (Wiley, 2024) Cadirci, Musa; Elibol, Erdem; Demirci, Tuna; Kurban, Mustafa
    In this study, CuLaSe2 and ZnCuLaSe2 quantum dots (QDs) with a mean size of similar to 4 nm were synthesized and characterized, and their temperature-dependent photoluminescence (PL) properties were studied in the temperature range from 90 to 300 K for the first time. The results show that the obtained QDs were spherical and revealed excitonic band gaps. The PL intensity for both types of materials decreased when increasing the temperature to 300 K, which was attributed to the nonradiative relaxation and thermal escape mechanisms. As the temperature was increased, the PL linewidths broadened, and PL peak energies were red shifted for both types of QDs due to the exciton-phonon coupling and lattice deformation potential mechanisms. In addition, we found that as the temperature was decreased, the PL spectrum of ZnCuLaSe2 QDs contained two extra components, which could be attributed to the shallow defect sites (low energy peak) and the crystal phase transition process (high energy peak). The spectrum of CuLaSe2 QDs contained one extra component, which could be attributed to the crystal phase transition process.
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    Synthesis of Highly Monodisperse CdSe Quantum Dots and Size Dependency of Optical Properties
    (Gazi Univ, 2021) Cadirci, Musa; Demirci, Tuna
    Semiconductor quantum dots have wide application areas as they have unique electrical and optical properties. In recent years, CdSe quantum dots are one of the most preferred nanomaterials. Highly monodisperse zinc blend CdSe quantum dots were synthesized using hot injection method. The structure and optical properties of the samples were determined by UV-Vis, photoluminescence, XRD and TEM methods. As a result, the difference between 2S-1P absorption transitions did not change with particle size. However, the difference between 1S-2S and 1S-1P transitions were found to be inversely proportional to particle size. The FWHM value of the photoluminescence spectrum of the smallest sample has decreased to 25 mm and Stokes shifts were observed to be 0.06 eV.
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    Temperature-dependent photoluminescence of CdSe/CdTe quasi-type-II quantum dots
    (Elsevier, 2020) Cadirci, Musa
    Temperature-dependant photoluminescence (PL) properties of CdSe/CdTe quasi-Type-II QDs are studied using steady-state PL spectroscopy. It is observed that the PL intensity decreased as the temperature increased due to non-radiative thermal escapes and surface trap relaxations. The inverse relationship between PL peak energy and the temperature is ascribed to the exciton-phonon coupling and lattice deformation potential. The existence of surface trap relaxation and exciton-phonon coupling are further confirmed with the direct relationship between PL linewidth and temperature up to a certain point. A second peak, which has temperature-dependant properties, is observed at higher energies and it is attributed to the formation of CdTe core during shell growth process.
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    Third order nonlinear investigations of CuLaSe2 and ZnCuLaSe2 quantum dots
    (Elsevier, 2023) Gundogdu, Yasemin; Cadirci, Musa; Kilic, Hamdi Sukur; Elibol, Erdem
    Environmentally friendly quantum dots (QDs) with high two-photon absorption coefficients in the near-infrared region are important for nonlinear optics (NLO) applications. In this work, CuLaSe2 and ZnCuLaSe2 QD are successfully synthesized and characterized using UV-Vis, Photoluminescence and HRTEM analysis. Next, the third-order NLO properties of these materials are studied using the femtosecond Z-scan method. The samples showed efficient nonlinear responses. The nonlinear absorption coefficient (& beta;), the nonlinear refractive index (n2) and the third-order nonlinear susceptibility (& chi;(3)) values for all samples are deduced and discussed in detail. The results reported here pave the way towards building CuLaSe2 and ZnCuLaSe2 QDs-based nonlinear photoelectric devices operating in the near-infrared field.
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    Third order nonlinear optical properties of CdTe/CdSe Quasi Type-II Colloidal Quantum Dots
    (Elsevier, 2021) Gundogdu, Yasemin; Kilic, Hamdi Sukur; Cadirci, Musa
    Core/shell Colloidal Quantum Dots (CQDs) are of interest for nonlinear photonic applications due to their unique properties. In this work, firstly CdTe/CdSe Quasi Type-II Colloidal Quantum Dots with an average core size of 3.54 nm and four different shell thicknesses (1.8 nm, 2.7 nm, 3.2 nm and 3.8 nm) were synthesized and characterized using UV-Vis spectroscopy and Transmission electron microscopy (TEM). Secondly nonlinear optical properties of these structures were determined using Femtosecond Z-scan method at the wavelength of 800 nm. Measured values for two photons absorption coefficients (beta) and nonlinear refractive indices (n2) were found to be on the orders of 10-11 cm/W and 10-16 cm2/W, respectively. In addition, the third order nonlinear optical susceptibility values for these structures were calculated to be on the order of 10-10 esu. Quantum dots with thicker shells exhibited faintly higher nonlinear absorption coefficient and slightly lower third order nonlinear optical susceptibility values compared with that of thinner shells. Furthermore, pump power dependant nonlinear optical properties of core/shell nano-structures were investigated and it is observed that two photons absorption coefficient and the third order nonlinear optical susceptibility are pump dependant, while nonlinear refractive indices does not respond to the pump power.
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    Third-order nonlinear optical properties of CsPbCl3 and CsPbBr3 perovskite quantum dots: Effects of particle size and surface traps
    (Elsevier, 2023) Cadirci, Musa; Gundogdu, Yasemin; Bakay, Melahat Sevgul; Kilic, Hamdi Sukur
    Particle size and surface trap effects on the third-order nonlinear optical (NLO) properties of CsPbCl3 and CsPbBr3 perovskite quantum dots (PQD) have been investigated using a femtosecond (fs) z-scan experiment. Firstly, optical, morphological, and structural characterizations of the synthesized PQDs were performed using linear absorption and photoluminescence (PL) spectra, XRD, and TEM methods. Next, NLO properties of CsPbCl3 and CsPbBr3 PQDs were studied at the operating wavelength of 800 nm and 3.564 x 1011 W/cm2 laser intensity. The nonlinear absorption coefficient (& beta;), the nonlinear refraction coefficient (& gamma;), and the third-order susceptibilities (& chi;(3)) values for both sample types were calculated to be on the order of 10-11 m/W, 10-17 m2/W, and 10-11 esu, respectively. The effects of particle size and surface trap sites on the nonlinear properties of the PQDs were studied thoroughly. & gamma;, & chi; (3), and the unitless nonlinear figure of merits (FOM) parameters were realized to be proportional to the particle size for both types of materials. In addition, these parameters were improved by decreasing the surface trap sites in the PQDs. These results strongly indicate the significant potential of CsPbCl3 and CsPbBr3 PQDs for numerous nonlinear applications.