INVESTIGATION OF PHOTOELECTRIC CONVERTERS WITH A BASE CADMIUM TELLURIDE LAYER WITH A DECREASE IN ITS THICKNESS FOR TANDEM AND TWO-SIDED SENSITIVE INSTRUMENT STRUCTURES

Photovoltaic cells with a base layer of cadmium telluride with a decrease in its thickness are studied. It is known that the widespread use of photovoltaic converters is constrained by their high price in the case of highly efficient instrument structures, or low efficiency. The creation of tandem and two-sided sensitive photoelectric converters will reduce their cost while increasing their efficiency. However, to create tandem and two-sided sensitive photoelectric converters, the necessary conditions are the use of transparent contacts and a decrease in the thickness of the base layer for efficient absorption of incident radiation by the converter, which is lower. In the research process, it was found that reducing the thickness of the base layer to 1 μm allows to increase the efficiency of the photoelectric transducer during irradiation from the back. An increase in the efficiency of the photoelectric converter occurs due to a decrease in the distance from the generation region of nonequilibrium charge carriers in the region of separation. If the thickness of the base layer is less than 1 μm, then regardless of which side of the irradiation is carried out, a decrease in the efficiency of the instrument structure is observed. Increase in the efficiency of photoconverters is associated with an increase in the negative influence of recombination processes on the back contact, a decrease in the number of charge carriers generated due to incomplete absorption of incident radiation, and a decrease in the volume of the built-in field of the separating barrier when it overlaps with the depletion region of the back contact. ITO/CdS/CdTe/Cu/ITO SCs with a base layer thickness of 1 μm demonstrates degradation stability. The highest value of efficiency in the case of illumination from the front side 8.1 % and with illumination from the back side 3.8 % received after a year of operation of the photovoltaic converter.

Механизмы токопрохождения в полупроводниковой структуре фотоэлектрического преобразователя с n-=SUP=-+-=/SUP=--p-переходом и антиотражающей пленкой пористого кремния, сформированной методом окрашивающего травления

We have studied experimental samples of photoelectric transducers with an n ^+– p junction based on a silicon single crystal and an antireflection porous silicon (por-Si) film formed by color chemical etching in a HF : KMnO_4 : C_2H_5OH etcher. It is shown that for KMnO_4 oxidant concentrations of 0.025 and 0.040 M, the por-Si film growth time at which the maximal efficiency of the photoelectric transducer is reached can be substantially increased as compared to that attained using anode electrochemical etching. For investigating the current transmission mechanisms, we have measured the temperature dependence of forward- and backward-bias current–voltage branches. The existence of several current transmission mechanisms has been established. It is found that traps with activation energy distributed in a continuous range of values considerably affect the current transmission.

Versatile Protein-A Coated Photoelectric Immunosensors with a Purple-Membrane Monolayer Transducer Fabricated by Affinity-Immobilization on a Graphene-Oxide Complexed Linker and by Shear Flow

Bacteriorhodopsin-embedded purple membranes (PM) have been demonstrated to be a sensitive photoelectric transducer for microbial detection. To efficiently prepare versatile BR-based immunosensors with protein A as antibody captures, a large, high-coverage, and uniformly oriented PM monolayer was fabricated on an electrode as an effective foundation for protein A conjugation through bis-NHS esters, by first affinity-coating biotinylated PM on an aminated surface using a complex of oxidized avidin and graphene oxide as the planar linker and then washing the coating with a shear flow. Three different polyclonal antibodies, each against Escherichia coli, Lactobacillus acidophilus, and Streptococcus mutans, respectively, were individually, effectively and readily adsorbed on the protein A coated electrodes, leading to selective and sensitive quantitative detection of their respective target cells in a single step without any labeling. A single-cell detection limit was achieved for the former two cells. AFM, photocurrent, and Raman analyses all displayed each fabricated layer as well as the captured bacteria, with AFM particularly revealing the formation of a massive continuous PM monolayer on aminated mica. The facile cell-membrane monolayer fabrication and membrane surface conjugation techniques disclosed in this study may be widely applied to the preparation of different biomembrane-based biosensors.

Effects of Ca2+ withdrawal on diaphragmatic fiber tension generation

The effects of extracellular Ca2+ withdrawal were studied on isolated diaphragmatic muscle fibers and compared with the effects on the papillary, soleus, and extensor digitorum longus (EDL) contractility, using the same in vitro model. Diaphragmatic fibers were obtained from 15 rats, and papillary muscles, soleus, and EDL were obtained from 10 animals. Isometric force generated in response to 1-Hz supramaximal electrical stimulation was measured with a highly sensitive photoelectric transducer. After control measurements, perfusion with a Krebs solution depleted of calcium (0 Ca2+) was started while the fibers were continuously stimulated (4 times/min) and twitches recorded. For the papillary fibers, perfusion with zero Ca2+ was followed by an immediate decrease in twitch tension, complete twitch abolition occurring within 3 +/- 1 min after zero-Ca2+ exposure. Diaphragmatic fibers behaved similarly, although twitch abolition was delayed (10 +/- 3 min after 0-Ca2+ exposure). For the soleus fibers, the twitch amplitude amounted to 38 +/- 10% of control (62% decrease on the average) after 30 min of zero-Ca2+ exposure, no twitch abolition being noted even after 1 h of Ca2+-free exposure. The twitch amplitude of the EDL fibers amounted to 75 +/- 7% of control (25% decrease) after 30 min of zero-Ca2+ exposure. The recovery kinetics for the four fiber types after reexposure to Ca2+-containing solution were also different, with papillary and diaphragmatic fibers recovering completely within 2.5 +/- 0.5 and 4 +/- 0.5 min, respectively. By contrast, neither the soleus nor the EDL showed complete recovery after 30 min.(ABSTRACT TRUNCATED AT 250 WORDS)