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Two novel V-shaped push-pull systems based on a pyrimidine acceptor have been designed and investigated. Low-temperature measurements of the fluorescence and delayed luminescence spectra demonstrated that the emission bands of the compounds have a charge-transfer character. Despite the fact that compounds in thermal vacuum deposition films have a low fluorescence quantum yield, OLED devices based on them show high efficiency, which can be associated with the emission mechanism through delayed fluorescence. It is found that photoproducts, obtaining upon exposure to UV-irradiation of fluorophores in chloroform solution, exhibit laser activity in the red region of the spectrum.

The manufacturing process of wide-band-gap matrix photodetector devices and miniaturization of their individual pixels gave rise to increased demands on the material quality and research methods. In the present paper we propose using the methods of atomic-force microscopy to study the local distribution of electrical properties of the V-defects that form in epitaxial films of HgCdTe during their growth process via molecular beam epitaxy. We demonstrate that a complex approach to studying the electrical properties of a predefined region of a V-defect allows one to obtain more detailed information on its properties. Using scanning spreading resistance microscopy, we show that, for a V-defect when the applied bias is increased, the surface area that participates in the process of charge carrier transfer also increases almost linearly. The presence of a potential barrier on the periphery of individual crystal grains that form the V-defect interferes with the flow of current and also affects the distribution of surface potential and capacitive contrast.

Organic Light Emitting Dioides (OLED)devices were fabricated with blue emission based on azatrioxa[8]circulene and 4,4-N,N'-Dicarbazolyl-1,1'-biphenyl (CBP) with maximum brightness of 840 kd/m(2) at 12 V and the starting voltage of 3.5 V. The vibronic emission spectrum was analyzed by the promotive modes calculation method. The electroluminescence of fabricated OLED device is caused by the 0-0 electronic transition and single excitations of 1473 cm(-1) and 1673 cm(-1) modes and combinations thereof.

A series of novel D–A and D–π–A push-pull systems based on a pyrazine and quinoxaline acceptor, bearing various electron-donating triphenylamine and carbazole moieties, are compared. A significant difference in electrochemical and photophysical properties was found depending on molecular structure. The compounds have strong solvatochromic properties. Quinoxaline-containing systems exhibit delayed fluorescence (DF) in thermal vacuum deposition films. Despite the low quantum yield of fluorescence in the solid state (less than 10%), organic light-emitting diodes with sufficiently high efficiency (4.2 cd/A) have been fabricated on the basis of this push-pull systems. The best results were obtained for compounds exhibiting DF. The possible channel for increasing the efficiency of OLED can be associated with the “hot excitons” mechanism.

The epitaxial growth of CdHgTe films is accompanied by the formation of V defects whose density and electronic properties greatly affect the characteristics of a terminal device based on the given material. Scanning atomic-force microscopy techniques are proposed to investigate how electronic properties vary in the V-defect region of an epitaxial CdHgTe film. It is experimentally demonstrated that variations in the component composition of individual crystallites generating V defects create not only the complex spatial distribution of a potential field but also a potential barrier along the crystallite periphery. The given barrier must alter the charge-carrier exchange between crystallites, appreciably changing the current distribution over the V-defect area.

Numerous theoretical and experimental studies show that during epitaxial growth according to the Stranski-Krastanow mechanism in systems mismatched by the lattice constant, the change in the surface energy of the system during nucleation and further growth of quantum dots, plays the most important role. In particular, this factor determines the equilibrium and critical thicknesses of the transition from two-dimensional to three-dimensional growth, and also affects other kinetic characteristics of the ensemble of nanoclusters, including the nucleation rate, surface density, and average size of the islands. Recent theoretical studies have made it possible to determine that the surface energy in this process depends on the thickness of the material deposited on the substrate. In this paper, we construct a kinetic model of the formation and coherent growth of two-dimensional layers and quantum dots in mismatched epitaxial systems, taking into account the dependence of the specific surface energies on the thickness of the deposited material. In this approximation, we calculate the basic parameters of the formed array of nanoislands. Experimental studies were also carried out on the growth of two-dimensional layers and quantum dots of germanium on the silicon (100) surface. The results of experimental investigations confirm the proposed theoretical model.

In this paper the local distribution of the material composition in the V-defect region of HgCdTe epitaxial films is investigated. The local composition distribution is studied by the Kelvin Force Probe Microscopy method and scanning electron microscopy with energy dispersive X-ray analysis. It is demonstrated that in the V-defect region of a Hg 1−x Cd x Te epitaxial film inhomogeneous distribution of the material component composition is observed. Analysis of the obtained experimental data shows that V-defects are distinguished by an increased mercury content.

The effect of a high-frequency nanosecond volume discharge forming in an inhomogeneous electrical field at atmospheric pressure on the CdHgTe (CMT) epitaxial films is studied. The measurement of the electrophysical parameters of the CMT specimens upon irradiation shows that that the action of pulses of nanosecond volume discharge leads to changes in the electrophysical properties of CMT epitaxial films due to formation of a near-surface high-conductivity layer of the n-type conduction. The preliminary results show that it is possible to use such actions in the development of technologies for the controlled change of the properties of CMT narrow-band solid solutions and production of structures heterogeneous with respect to conduction.

In this paper we present the results of our research of the impact of nanosecond volume discharge on the electronic properties of the near-surface region of epitaxial Hg1−x Cd x Te films. We show that the distribution of the surface potential and, as a consequence, the material composition of the individual crystal grains that form V-defects possess a complex structure and contain regions with elevated content of both mercury and cadmium. The volume discharge treatment of the film surface leads to a decrease of the mercury content in individual crystal grains compared to the bulk of Hg1−x Cd x Te epitaxial film. This indicates a higher mercury desorption rate from the V-defect region.