The organic photovoltaic cell (OPV) is composed of multiple layers, and some printing and coating techniques are more suitable than others for a certain type of layer. This paper aims to characterize and compare the most relevant coating and printing techniques that can be used in the manufacture of OPVs. Extensive bibliographic research was carried out on articles published from 1998 to 2020 to identify various aspects OPV, such as the principle of operation, advantages, disadvantages, and which layers can be printed by each technique. The results show that the most used method for the processing of OPVs is spin-coating. In the studies found, rotation was used to coat the active layer, the electron transport layer, and the hole transport layer. The techniques of pad printing, casting, and meniscus are considered useful in the processing of the active layer. Regarding the deposition of the active layer, hole transport layer, electron transport layer, and anode, the rotogravure, crack matrix, spraying, and brushing techniques were satisfactory. Flexography has been used to form the active layer, electron transport layer, and anode. Screen printing, inkjet printing, and knife/blade coating were used in the processing of the active layer, hole transport layer, electron transport layer, anode, and cathode. All the double slot die coating, curtain coating, and slide coating allows simultaneous processing of multiple layers. Techniques compatible with roll-to-roll processing are more likely to be at the center of OPVs in the future, thus making solar photovoltaic technology more competitive.

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There are many technologies that may emerge and eventually disappear over the years. This fact makes the monitoring of technological trends as well as the anticipation of the direction of technological change paramount. This article aims to carry out the prospection of technologies, focusing on its technicalcommercial viability, for solar photovoltaic energy. The research method had a qualititative-quantitative approach with application of the Delphi technique. In the conduction of the Delphi technique, seven steps were followed, ranging from the selection of the specialists to the considerations of their opinions regarding the future of nine photovoltaic technologies. The results of the research indicate that in 2020, the cells monocrystalline, multicrystalline, and amorphous silicon; cadmium telluride; indium/copper selenide, indium, and gallium diselenide; and multicompound III-V cells will have technical and commercial viability and that dye-sensitized silicon nanowire and carbon nanostructure-based cells will not be viable. For the year 2025, monocrystalline and multicrystalline silicon cells and those of multicompounds III-V will still be technically and commercially viable. Silicon nanowire; amorphous silicon; cadmium telluride; indium/copper, selenium, and gallium diselenide dyesensitized cells; and organic photovoltaic cells, including those based on carbon nanostructure, may be viable. This study is important, because the technological prospecting of the photovoltaic cells determines the possible trajectories of these cells, in a way that helps the companies of the sector to anticipate the strategic scenarios, thus facilitating the decision making process.

This work aims to analyze the factors that influence the radiation properties of dualband microstrip antenna using periodic structures based on Photonic Band Gap with hexagonal symmetry. An increase in bandwidth and a reduction of return loss for the second operating band of the antenna were observed.

This article presents an investigation about the parameters of rectangular microstrip patch antennas with resonators on the antenna's substrate, through a experimental collection, it has been observed a simulation analysis and its verification by measured data. This investigation refers to two arrayed sets on the substrate, the first one with 16 resonators and the second one with 36. The substrate composition of the antenna have been based on the use of split ring resonators, periodically organized on arrays and confined on the substrate. By applying this proposal, it has been made an evaluation of return loss behavior related to the operation frequency, bandwidth, gain, and feature impedance, in which intended to compare the obtained values to each spacial disposition of the resonator elements. The result analysis demonstrated acceptable agreement between simulated and measured values.