Wyniki wyszukiwania - BazTech

1

Synthesis of a New Random Copolymer Based on Glycidyl Nitrate and Tetrahydrofuran : A Thermal, Kinetic, and Theoretical Study

Alizadeh Milad, Bayat Yadollah

Central European Journal of Energetic Materials

|

2024

|

Vol. 21, no. 1

5--21

EN

Today, polymeric binders are regarded as playing a crucial role in solid propellants. Therefore, research aimed at improving the performance of the binder is particularly important. In this study, a new energetic random copolymer of glycidyl nitrate (GN) and tetrahydrofuran (THF), poly (THF-ran-GN) (Mn = 1561 g mol⁻¹) was synthesized using the cationic ring-opening polymerization process. The chemical structure of the prepared copolymers was characterized utilizing FT-IR, ¹H NMR and ¹³C NMR spectroscopic techniques. The thermal properties of the copolymers and their molecular weights were investigated by thermogravimetric analysis (TGA), differential thermal analysis (DTA), differential scanning calorimetry (DSC) and gel permeation chromatography (GPC). The results showed that the glass transition temperatures (Tg) of the synthesized copolymers (Tg= -59 °C) were lower than those of pure PGN (Tg= -32 °C). Therefore, copolymerization led to a decrease in the Tg temperature. The kinetic parameters of the DSC were determined in the non-isothermal framework described by Kissinger. The electronic structure of the copolymers was also simulated with the Gaussian 09 program package in order to investigate the optoelectronic properties of the copolymers based on time dependent density functional theory (TD-DFT) computations. In addition, the existence of three peaks featuring significant excitations associated with electron transition in frontier orbitals was demonstrated. The results showed that the new synthesized random copolymer has energetic properties.

2

Annealing effect on the structural and optoelectronic properties of Cu-Cr-O thin films deposited by reactive magnetron sputtering using a single CuCr target

Tsai Du-Cheng, Chen Erh-Chiang, Huang Yen-Lin, Shieu Fuh-Sheng, Chang Zue-Chin

Materials Science Poland

|

2023

|

Vol. 41, No. 1

191--201

EN

The aim of this study is to explore the structural and optoelectronic properties of Cu-Cr-O thin films when processed by the magnetron sputtering method using a single equimolar CuCr alloy target. These films were then post-annealed in a controlled Ar atmosphere at 500°C to 800°C for 2 h. The as-deposited Cu-Cr-O thin film consisted of an amorphous phase and exhibited extremely poor optoelectronic properties. After annealing was conducted at 500°C, monoclinic CuO and spinel CuCr2O4 phases were simultaneously formed in the film. Upon increasing the annealing temperature to 600°C, the CuCr2O4 phase reacted completely with the CuO phase and transformed into the delafossite CuCrO2 phase, possessing optimal optoelectronic performance. It has an electrical resistivity of 41 Ω-cm and a light transmittance of 49.5%, making it suitable for p-type transparent conducting electrodes. A further increase in annealing temperature resulted in larger grains and greater surface roughness and void density, which, in turn, degraded the optoelectronic performance.

3

Structural, Electrical, and Optical Properties of ZnO Films Grown by Atomic Layer Deposition at Low Temperature

Park Ji-Young, Weon Ye Bin, Jung Myeong Jun, Choi Byung Joon

Archives of Metallurgy and Materials

|

2022

|

Vol. 67, iss. 4

1503--1506

EN

Zinc oxide (ZnO) is a prominent n-type semiconductor material used in optoelectronic devices owing to the wide bandgap and transparency. The low-temperature growth of ZnO thin films expands diverse applications, such as growth on glass and organic materials, and it is also cost effective. However, the optical and electrical properties of ZnO films grown at low temperatures may be inferior owing to their low crystallinity and impurities. In this study, ZnO thin films were prepared by atomic layer deposition on SiO2 and glass substrates in the temperature range of 46-141℃. All films had a hexagonal würtzite structure. The carrier concentration and electrical conductivity were also investigated. The low-temperature grown films showed similar carrier concentration (a few 1019 cm-3 at 141°C), but possessed lower electrical conductivity compared to high-temperature (>200°C) grown films. The optical transmittance of 20 nm thin ZnO film reached approximately 90% under visible light irradiation. Additionally, bandgap energies in the range of 3.23-3.28 eV were determined from the Tauc plot. Overall, the optical properties were comparable to those of ZnO films grown at high temperature.

4

Quinoxaline-based small molecules: synthesis and investigation on their optoelectronic properties

Deng J., Tao Q., Yan D., Huang X., Liao Y.

Materials Science Poland

|

2018

|

Vol. 36, No. 2

167--176

EN

Small molecules of ThQuTh, CzQuTh, CzQuCz and TPAQuCz were designed and synthesized, based on quinoxaline acceptor, and electron donating groups, i.e. alkyl-thioephene, carbazole and triphenylamine on both side chains and molecular backbones. Their thermal, optical and electrochemical properties were systematically compared and studied. The absorption spectra of the small molecules were strongly affected by the donor units attached to quinoxaline. Strong electron donating groups, such as carbazole on the molecular backbone would lower optical band gap, resulting in a wide absorption and the strong donor on the side chain would enhance the absorption intensity in short wavelength region. The highest occupied molecular orbital (HOMO) energy levels of the four molecules were up-shifted with increasing the electron donating properties of donor units. The bulk-heterojunction organic solar cells with a device structure of ITO/PEDOT:PSS/SMs:PC61BM/LiF/Al were fabricated, in which the small molecules functioned as donors while PC61BM as acceptor. Because the electron-donating ability of carbazole (Cz), triphenylamine (TPA) is higher than that of thiophene (Th), CzQuTh, CzQuCz and TPAQuCz show higher power conversion efficiency (PCE) than that of ThQuTh. Furthermore, being the strongest in absorption intensity and widest in absorption spectrum, TPAQuCz has the highest power conversion efficiency. Further improvement of the device efficiency by optimizing the device structure is currently under investigation

5

Tuning the Charge Transfer and Optoelectronic Properties of 4,6-Di(Thiophene-2-YL)Pyrimidine via Oligocenothiophene Substitution

Irfan A., Chaudhry A. R., Al-Sehemi A. G., Muhammad S., Jin R., Tang S.

Archives of Metallurgy and Materials

|

2018

|

Vol. 63, iss. 4

1629--1636

EN

Five new derivatives of 4,6-di(thiophen-2-yl)pyrimidine (DTP) were designed by structural modification with the aim to tune the electro-optical and charge transfer properties. The effect of oligocene and oligocenothiophene incorporation/substitution was investigated on various properties of interests. The smaller hole reorganization energy revealed that compounds 1-5 might be good hole transfer contenders. The smaller hole reorganization energy of newly designed five DTP derivatives than the pentacene showed that prior compounds might be good/comparable hole transfer materials than/to that of pentacene. The computed electron reorganization energy of DTP derivatives 1-5 are 124, 185, 93, 95 and 189 meV smaller than the meridional-tris (8-hydroxyquinoline) aluminum (mer-Alq3) illuminating that electron mobility of these derivatives might be better/comparable than/to referenced compound.