The charge generation–recombination dynamics in three narrow‐bandgap near‐IR absorbing nonfullerene (NFA) based organic photovoltaic (OPV) systems with varied donor concentrations of 40%, 30%, and 20% are investigated. The dilution of the polymer donor with visible‐range absorption leads to highly transparent active layers with blend average visible transmittance (AVT) values of 64%, 70%, and 77%, respectively. Opaque devices in the optimized highly reproducible device configuration comprising these transparent active layers lead to photoconversion efficiencies (PCEs) of 7.0%, 6.5%, and 4.1%. The investigation of these structures yields quantitative insights into changes in the charge generation, non‐geminate charge recombination, and extraction dynamics upon dilution of the donor. Lastly, this study gives an outlook for employing the highly transparent active layers in semitransparent organic photovoltaics (ST‐OPVs).
Photoactive Materials
Next‐generation photovoltaics will be lightweight, flexible, and (semi)transparent. Highly transparent organic photoactive materials are reported by Thuc‐Quyen Nguyen, Viktor Brus, and co‐workers in article number 2203796. The changes in the fundamental processes in solar cells comprising a near‐IR‐absorbing acceptor and a visible‐light‐absorbing donor are revealed upon dilution of the donor material, paving the way for integrated energy‐harvesting solutions based on semitransparent organic photovoltaics.
An overview of the prospects for the development of nuclear technologies and the conclusion of the relevant requirements for advanced structural materials, their classification and features were performed. In order to obtain a bar with a modified radiation-resistant outer layer, an experiment of radial-shear rolling under the most stringent conditions was carried out. For the same conditions, a FEM-simulation of sequential rolling in eight passes with a total compression of 70.7% (from a diameter of 37 mm to 20 mm) was conducted. For adequate simulation results a new material database for Zr-1%Nb alloy using plastometry investigations was generated. An experimental obtaining of a gradient-modified structure with an ultrafine-grained (UFG) periphery and an elongated rolling texture in the center of the bar was performed.
The work is devoted to the problem of quantitative evaluation of the microstructure on the example of work with the TEM study of ultrafine-grained (UFG) austenitic steel for use in nuclear power. The material was obtained by radial-shear rolling and has different features of the structural structure of the cross section (from the periphery to the center), which makes it relevant to the correct assessment of the microstructure, taking into account all the features. This is difficult to do correctly, using only existing simple methods (average grain size, degree of grain misalignment, phase ratio) and most importantly, the results can not always be compared with each other. For a more objective and unambiguous assessment of different types of microstructure, a new qualimetric technique for quantitative quality analysis was developed. The new technique made it possible to make a more correct comparison of changes in the quality of the rod microstructure and to evaluate the effectiveness of the technology. According to the assessment, the greatest improvement is experienced by the central zone of the bar, from 0.13 to 0.43, that is, more than 3 times. At the same time, the quality growth of the peripheral region is low (only 1.29 times) and tends to slow down. This is due to the fact that with an increase in the degree of deformation there is no further refinement of the structure, but only improves its shape, becoming more uniform, as also evidenced by the values of the mean square deviation, showing the minimum spread of values. The resulting methodology for the qualimetric evaluation of quality can be used to create free open of image processing algorithms (e.g. MathLab), and for commercial products for quantitative metallographic analysis.
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