فصلنامه نانو مقیاس
سال دهم شماره 1 (پیاپی 37، بهار 1402)

In the past few years, efforts to manufacture small atomic vapor cells have intensified, making it possible to build small, integrated frequency references, miniature optical clocks, and micron and nanometer sensors. In this direction and in order to increase the interaction of light and thermal alkali vapors, the optical interactions of the evanescent field with low optical power have been investigated in a micro-tapered fiber embedded in hot rubidium vapor. The results of transmission spectroscopy in these emerging cells show increased broadening compared to standard rubidium atomic vapor cells. In these micrometer systems, the possibility of nonlinear optical interactions with powers of milli watt-level is provided, despite the broadening of the transition-time much larger than the intrinsic broadening of the atom.

The use of hybrid diagnostic or diagnostic-therapeutic techniques together has accelerated and facilitated the process of cancer diagnosis and treatment and has played an important role in reducing patient mortality. In this regard, nanotechnology has been a leader by integrating nanomaterials and benefiting from their various capabilities, including optical and magnetic properties together. In this study, graphene oxide quantum dots incorporated with sulfur atoms and magnetic groups were synthesized in a simple single-step manner. GO@S-Fe3O4 QDs were characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR), UV–Vis spectroscopy, and vibrating sample magnetometer (VSM). Then, GO @ S-Fe3O4 quantum dots were labeled with high pure [68Ga] GaCl3. The radiochemical purity and stability of the 68Ga@GO@S-Fe3O4 QDs were examined using radio thin layer chromatography (RTLC). In-vivo bio-distribution studies in rat’s tumors were performed by intravenously injection of 68Ga@GO@S-Fe3O4 nanocomposite. Positron emission tomography (PET) imaging was done to investigate the distribution of radiopharmaceuticals in organs and tumor. The highest absorption in the tumor was observed 30 minutes after injection via the tail vein, which is due to the absorption tendency of 68Ga@Fe3O4@ GO nanoparticles in the tumor.

In this study, nanostructured SnS thin films were prepared using two complexing agents of ammonium acetate and hexamethylenetetramine (HMTA) by chemical bath deposition method on the glass andpolyethylene terephthalate (PET) substrate. The effect of complexing agents on surface morphology, structure, optical properties and particle size of the films were investigated by various techniques. The FE-SEM images of the samples showed that the SnS nanoparticles were coated as dense and homogenous on the substrate. The XRD results indicated that the SnS thin films well-crystallized and had orthorhombic crystal structure. The energy gap values of the films varied from 1.06 to 1.07 eV. The results of ultraviolet-visible spectrum of the samples showed that the SnS films had low transmittance values in the visible region, therefore they can be used as an absorber layer in the solar cells.

In perovskite solar cells, electron transfer can be improved by modifying the electron transporting layer. Previously, in perovskite solar cells, only C60 has been used as the electron transfer layer, but not its composite. In this research, the composite of TiO2 and C60 was used as an electron transporting layer in hole-transport-free perovskite solar cells. The results indicate that despite the decrease in abortion by the absorbent layer of the cell, the pattern of X-ray diffraction and photoluminescence show increase in crystallinity of perovskite layer. This results in better electron transfer. In addition, the surface of the electron transporting layer has been modified, which improves the performance of the solar cell. The efficiency of the fabricated perovskite solar cells was increased from 8.08 to 9.09.

: In this research, a Zigzag edge Silicene Nanoribbons (ZSiNR) photodetector having asymmetric doped source and drain electrodes has been simulated using the tight-binding approximation and taking account first nearest neighbors, coupling to Non-Equilibrium Green Function approach. The electronic characteristics including band energy structure and density of states of the Chanel and transport traits of the device such as photocurrent in terms of incident photon energy in the absent of external bias, moreover the dark current versus applied voltage to the drain have been determined. For theoretical assessment of device performance, monochromatic illumination in the range of has been used. The maximum photocurrent of this device is related to 438 nm illumination which resulted the quantum efficiency of 24%, photoresponsivity of 8.44 A/mW, and detectivity as much as ∼109 Jones. Variations of device total current versus drain voltage in dark and of monochromatic 438 nm illumination with different intensities has been assessed. It is revealed that, in constant applied voltage, as the illumination intensity increases the total device current reduces which is correspond to reduction of short circuit current of silicon solar cells.

Trying to discover the different characteristics of biosensor systems is the most important part of research development in various fields, especially in the field of biomolecular science. In this research, the biosensor properties of molecular graphene (Coronene, Circumcoronene and Circumcircumcoronene) have been investigated for their molecular size and chemical properties. Among the three mentioned structures, two of them (coronene and Circumcoronene) have been selected based on their properties for sequencing DNA molecules. Calculations were performed with the B3LYP hybrid function and 6-31G(d,p) basis set. After performing the necessary simulations and calculations, the results show that these graphene molecular structures can be used as biosensors.

In this research, the effect of aluminum cathode deposition rate on its structure and performance of organic light emitting diode (OLED) with Glass/ITO/PEDOT:PSS/ALq3 structure was investigated. The aluminum deposition rate was considered to be 0.1, 0.5, 1 and 2 nm/s. The structure of aluminum films was studied by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The results of structural characterization showed that the films prepared with rates of 0.1 and 0.5 nm/s have polycrystalline structure corresponding to the cubic phase of aluminum with a peak in the direction of the (111) plane. The morphology of the surface of the films is granular. Also, increasing the aluminum deposition rate cause to enhancing the size of grains and their surface roughness. The current-voltage characterization of diodes showed their diode behavior. In general, increasing deposition rate decreases the threshold voltage of the diodes. Light emitting spectroscopy of diodes showed that increasing the deposition rate of cathode cause to enhancing the intensity of their emitted light, but does not change the wavelength of the emitted light.

The present research deals with the fabrication and investigation of manganese cobalt ferrite's structural, magnetic and optical properties in the presence of polyaniline. The samples were prepared using in situ polymerization method. Then, the structural characteristics of the samples were analyzed by X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The magnetic properties of the samples were investigated by using Oscillating Sample Magnetometer (VSM). Examining the magnetic properties of the samples showed that the saturation magnetization value in both samples is 53.7 and 18.6 emu/g, respectively. These results show that the magnetic properties of ferrites can be controlled by using a polymer. Also, the optical properties of the samples were investigated by UV/visible absorption spectrometry. Two optical gaps were obtained by the Tauc method, 2.19 eV and 4.46 eV, and band gap energy was obtained at 2.73 eV using the PL for S2 sample.