Showing papers by "Anvar A. Zakhidov published in 2021"

Surface Energy-Driven Preferential Grain Growth of Metal Halide Perovskites: Effects of Nanoimprint Lithography Beyond Direct Patterning.

Abstract: Hybrid organic–inorganic lead halide perovskites have attracted much attention in the field of optoelectronic devices because of their desirable properties such as high crystallinity, smooth morpho...

Bright Single-Layer Perovskite Host–Ionic Guest Light-Emitting Electrochemical Cells

Abstract: Perovskite light-emitting devices have drawn considerable attention for their favorable optoelectronic properties. High carrier mobilities make perovskites excellent candidates as host materials in...

Enhanced Thermoelectric Properties of Poly(3-hexylthiophene) through the Incorporation of Aligned Carbon Nanotube Forest and Chemical Treatments.

Abstract: Carbon nanotube/polymer composites have recently received considerable attention for thermoelectric (TE) applications. The TE power factor can be significantly improved by forming composites with carbon nanotubes. However, the formation of a uniform and well-ordered nanocomposite film is still challenging because of the creation of agglomerates and the uneven distribution of nanotubes. Here, we developed a facile, efficient, and easy-processable route to produce uniform and aligned nanocomposite films of P3HT and carbon nanotube forest (CNTF). The electrical conductivity of a pristine P3HT film was improved from ∼10-7 to 160 S/cm thanks to the presence of CNTF. Also, a further boost in TE performance was achieved using two additives, lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) and tert-butylpyridine. By adding the additives to P3HT, the degree of interchain order increased, which facilitated the charge transport through the composite. Under the optimal conditions, the incorporation of CNTF and additives led to values of the Seebeck coefficient, electrical conductivity, and power factor up to rising 92 μV/K, 130 S/cm, and 110 μW/m K2, respectively, at a temperature of 344.15 K. The excellent TE performance of the hybrid films originates from the dramatically increased electrical conductivity and the improved Seebeck coefficient by CNTF and additives, respectively.

Ionically Gated Small-Molecule OPV: Interfacial Doping of Charge Collector and Transport Layer.

Abstract: We demonstrate an improvement in the performance of organic photovoltaic (OPV) systems based on small molecules by ionic gating via controlled reversible n-doping of multi-wall carbon nanotubes (MW...

Compositional Fibers Based on Coal Tar Mesophase Pitch Obtained by Electrospinning Method

Abstract: This research examines the use of coal-processing wastes of Shubarkol deposit (Kazakhstan) in obtaining useful materials such as carbon fibers. For our experiments, mesophase pitch was obtained by coal tar heat treatment at 773 K. Spinnable solution was prepared by crushing mesophase pitch into the pieces with adding poly(methylmethacrylate) as a fiber-forming material and 1,2-dichloroethane as a solvent. Elemental analysis revealed that the chemical composition of mesophase pitch (С – 91.48 %; О – 8.52 %; S – 0.00 %) showed that heat treatment up to 773 K leads to the complete removal of sulfur-containing components which affect the mesophase formation. Raman data of the obtained pitch revealed the appearance of D (1366 cm-1) and G (1605 cm-1) peaks, which are responsible for carbon materials; another peak at 2900 cm-1 shows the presence of C–H bonds. Carbon fibers with the diameter of 0.8–1.75 μm were obtained by electrospinning method in laboratory settings.

An improved model for describing the net carrier recombination rate in semiconductor devices

Abstract: Carrier recombination is a process that significantly influences the performance of semiconductor devices such as solar cells, photodiodes, and light-emitting diodes (LEDs). Therefore, a model that can accurately describe and quantify the net carrier recombination rate in semiconductor devices is important in order to further improve the performance of relevant semiconductor devices. The conventional model for describing the net carrier recombination rate is derived based on the condition that there is no electric current in the considered semiconductor, which is true only when the semiconductor is not part of a semiconductor device, and hence is not connected to an external circuit. The conventional model is adopted and used for describing the net carrier recombination rate in semiconductors that are part of devices (i.e. in semiconductor devices). In this paper, we derive and propose a new model for describing the net carrier recombination rate in semiconductor devices. The newly proposed model is an improvement to the currently used model by considering the fact that electric current can flow in the semiconducting materials of semiconductor devices. We validate the proposed recombination model and show that the use of the proposed model can be crucial for modeling and analyzing the performance of optoelectronic devices such as solar cells and LEDs.

Twisted laminar superconducting composite: MgB2 embedded carbon nanotube yarns

Abstract: Twisted laminar superconducting composite structures based on multi-wall carbon nanotube (MWCNT) yarns were crafted by integrating magnesium and boron homogeneous mixture into the carbon nanotube (CNT) aerogel sheets. After the ignition of the Mg–B–MWCNT system, under the controlled argon environment, the high exothermic reaction between magnesium (Mg) and boron (B) with stoichiometric ratio produced the MgB2@MWCNT superconducting composite yarns. The process was conducted under the controlled argon environment and uniform heating rate in the differential scanning calorimetry and thermogravimetric analyzer. The XRD analysis confirmed that the produced composite yarns contain nano and microscale inclusions of superconducting phase of MgB2. The mechanical properties of the composite twisted and coiled yarns at room temperature were characterized. The tensile strength up to 200 MPa and Young’s modulus of 1.27 GPa proved that MgB2@MWCNT composite is much stiffer than single component MgB2 wires. The superconductive critical temperature of Tc ~38 K was determined by measuring temperature-dependent magnetization curves. The critical current density, Jc of superconducting component of composite yarns was obtained at different temperatures below Tc by using magnetic hysteresis measurement. The highest value of Jc = 3.39 × 107 A cm−2 was recorded at 5 K.