Search Results (22)

Perovskite solar cells (PSCs) offer a number of key advantages over silicon solar cells. These include their low-cost materials, high efficiency, simplicity of fabrication, and inexpensive manufacturing techniques. To commercialize PSCs, there are many methods to develop the quality of the cells, one of them being printing techniques. Different printing techniques deposition have been developed for the perovskite solar cell, such as blade coating, slot die coating, inkjet printing, screen printing, spray coating, flexographic printing, and gravure printing. These techniques have a substantial impact on the performance of PSCs and controlling film formation to commercialize PSCs. This review summarizes a comprehensive overview of various deposition printing techniques used to fabricate PSCs during different years and different techniques, such as using different preparation methods, novel drying techniques, and ink engineering. In addition, the challenges that are faced by using these, such as material stability, reproducibility of printing processes, and cost-effectiveness techniques, are reviewed. Future research should focus on optimizing printing techniques to improve the stability and scalability of PSCs. Exploring novel perovskite materials, deposition techniques, and innovative fabrication methods may further enhance the PSCs and facilitate their commercialization. Full article

Flexo printing is a relief printing system, and ink transfers on the solid areas are not transferring well during the printing. That is why graininess is increasing and pinholes are occurring on the solid areas. This is a well-known issue in the flexo printing system. Micro-patterns usually eliminate these pinholes. Using correct micro-patterns allows homogeneous ink laydown and increases solid ink density. Micro-pattern holes behave like gravure cylinders on plate surfaces, and this makes for better ink transfer to the substrate. In this study, a more successful micro-pattern structure than the ones currently used was found by examining the solid ink density (SID) values and ink laydown obtained from the structure by producing eight different micro-pattern structures of 1000 LPI and 1500 LPI (line per inch) pattern screen frequencies with the same polymer structure and type. Densitometric values of solid prints made with the developed micro-patterns were measured. By eliminating the pinholes formed in solid prints and at the screen dot shapes, the ink is distributed more homogeneously without graininess. It has been determined that this results in a more stable measurement of ink density and eliminates the measurement of excess ink and low density. Full article

Flexographic printing is widely used in the packaging field, but there are still some problems in the printing of flexographic ink on non-absorbent substrates, such as low precision and unstable quality. In this paper, the printing process of flexographic ink is simulated. The interaction of fluid flow, temperature change, and solid deformation in flexographic printing is studied systematically by using the method of fluid–solid thermal coupling for the first time. The process of ink channel formation under static extrusion and fluid–solid thermal coupling was analyzed. The influences of printing pressure, printing speed, ink layer thickness, and ink viscosity on the ink channel were explored. The results show that the printing speed increases and the temperature in the stamping area increases. The printing speed is nonlinear related to the ink flow channel, the influence on the channel is slow at a low speed, the channel increases sharply at a medium and high speed, and tends to be stable at a high speed. When the printing speed is 200 m/min, the ink temperature in the stamping area is 1.5 °C higher than that at the entrance. With an increase in printing pressure, the ink flow channel width showed a trend of decreasing first and then stabilizing, and the pressure was about 0.4 MPa, showing a small fluctuation; the greater the pressure, the higher the temperature of the ink, which will change the performance of the ink and plate, causing adverse effects on the printing belt. The channel width showed obvious nonlinear characteristics with an increase and decrease in ink thickness. When the ink thickness is 30 μm, the deformation of the plate reaches the maximum, and the width of the ink circulation channel is correspondingly the widest. The change in ink viscosity has little influence on the stability of the ink’s internal flow rate and temperature field. The research results provide theoretical support for the transfer of ink printing from gravure to flexo printing. Full article

This work provides a method for the development of conductive water-based printing inks for gravure, flexography and screen-printing incorporating commercial resins that are already used in the printing industry. The development of the respective conductive materials/pigments is based on the simultaneous (in one step) reduction of silver salts and graphene oxide in the presence of 2,5-diaminobenzenesulfonic acid that is used for the first time as the common in-situ reducing agent for these two reactions. The presence of aminophenylsulfonic derivatives is essential for the reduction procedure and in parallel leads to the enrichment of the graphene surface with aminophenylsulfonic groups that provide a high hydrophilicity to the final materials/pigments. Full article

In recent years, due to environmental awareness regarding the harmfulness of polymeric materials, there has been a growing interest in using papers, especially those from alternative raw materials. The importance of using all available raw materials is imperative today. Raw materials that were once viewed as waste are now of great importance because they have the ability to replace raw materials that are used irrationally or are lacking. Cereal straw is a lignocellulosic material that could be used in the paper industry and in the production of increasingly prevalent paper packaging. The aim of this research was to analyze the relationships between the qualitative parameters of straw-based printed papers containing 30% agricultural residues (wheat, barley, or triticale). The influence of two qualitative parameters (ink penetration depth and optical ink density) on the print-through was observed using multiple regression analysis on straw-based papers produced at the laboratory level. Throughout the research, 100% recycled wood paper was used as a reference sample. The results of the regression analysis showed that none of the variables individually make a statistically significant contribution to the prediction of the dependent variable in a linear context, that is, they indicate a non-linear interaction between the variables and the specific conditions under which the dependent variable reaches local extremes and changes in the gradient. Considering the results of the regression analysis and the visualization of the relationship, the model was additionally tested with other independent variables (paper type). From the results obtained, it can be concluded that the alternative straw-based paper with 30% barley pulp has the best interaction between ink and paper, which is the most similar to the reference sample in terms of printability, while the alternative straw-based paper with 30% wheat generally differs significantly from the reference paper when all three prints are considered. Full article

Interest in printed batteries is growing due to their applications in our daily lives, e.g., for portable and wearable electronics, biomedicals, and internet of things (IoT). The main advantages offered by printing technologies are flexibility, customizability, easy production, large area, and high scalability. Among the printing techniques, gravure is the most appealing for the industrial manufacture of functional layers thanks to its characteristics of high quality and high speed. To date, despite its advantages, such technology has been little investigated, especially in the field of energy since it is difficult to obtain functionality and adequate mass loading using diluted inks. In this review, the recent results for printed lithium-ion batteries are reported and discussed. A methodology for controlling the ink formulation and process based on the capillary number was proposed to obtain high printing quality and layer functionality. Specific concerns were found to play a fundamental role for each specific material and its performance when used as a film. Considering all such issues, gravure can provide high performance layers. A multilayer approach enables the desired layer mass loading to be achieved with advantages in terms of bulk homogeneity. Such results can boost the future industrial employment of gravure printing in the field of printed batteries. Full article

In recent years, researchers prepared composite conductive inks with high conductivity, high thermal conductivity, strong stability, and excellent comprehensive mechanical properties by combining carbon-based materials such as graphene and carbon nanotubes with metal-based materials. Through new electronic printing technologies, conductive inks can be used not only to promote the development of integrated circuits but also in various new electronic products. The conductive mechanism and the main types of conductive inks are introduced in this review. The advantages of electronic printing technology for preparing integrated circuits are analyzed. The research progress of fabricating integrated circuits with different electronic printing processes, such as screen printing, gravure printing, flexographic printing, and inkjet printing, are summarized. The development trend of carbon-based composite conductive ink for integrated circuits is prospected. Full article

In light of the growing interest in printed batteries, we recently demonstrated the possibility of employing industrial gravure printing in battery manufacturing. Gravure is the most appealing printing technique for the low-cost production of functional layers, but it is rarely investigated since the necessity to use diluted inks makes it difficult to obtain proper functionality, especially in the case of composites, and an adequate mass loading of the printed layer. For this reason, the ink formulation represents one of the main challenges; ruling on it could strongly boost the use of such a technique in industrial manufacturing. It is known that a viable method for obtaining good gravure printing quality is based on the Capillary number approaching unity. Taking into account such methods for the choice of ink and the process parameters, here a study of the printing quality influence on the functionality and the performances of the gravure printed layer is proposed in the case of an LFP-based cathode for Li-ion batteries. Good printing quality is necessary to obtain proper layer functionality, but specific parameters have to be considered for achieving high performance. Full article

In this article, a facile way for the doping of graphene and graphene derivatives with silver nanoparticles at different Ag ratios is described. Ag nanoparticles were formed directly on the surface of two different graphene substrates dispersed in dimethylformamide by the reduction of Ag cations with NaBH₄. A few layered graphene nanosheets (FLG) produced from graphite and reduced graphene oxide functionalized with amino arylsulfonates (f-rGO) were used as substrates. The final graphene/Ag nanoparticle hybrid in the form of solid, dense spots showed enhanced electrical conductivity, which can be attributed to the formation of conductive interconnections between the 2D nanosheets. Importantly, electrical conductivities of 20 and 167 10³ S m⁻¹ were measured for the hybrids of f-rGO and FLG, respectively, with the higher Ag percentage without an annealing process. A representative hybrid f-rGO with Ag nanoparticles was used for the development of a highly conductive water-based gravure ink with excellent printing properties. Full article

Packaging and labels are used for a variety of products and have become an indispensable part of daily life, while products without labels or packaging cause uncertainty among consumers. The global trend is to reduce the amount of packaging waste by recycling and reusing the same material or using other available waste raw materials. With large quantities of stalks remaining discarded in the fields after harvest each year, cereal straw is emerging as an alternative source of lignocellulosic fibers for secondary green packaging and labels. In this study, the usability of printed papers with discarded lignocellulosic fibers by offset and gravure printing processes for secondary green packaging and labels was observed based on the qualitative parameters of reproduction and ink penetration into the printing substrate. From the obtained results, it can be concluded that gravure prints have greater penetration of the ink into the printing substrate, resulting in more uneven surface coverage with printing ink, compared to offset prints, where the viscosity of the ink and the printing process itself have the greatest influence. Therefore, these substrates with discarded lignocellulosic fibers can be used for secondary green packaging and labeling printed by the offset printing process, while gravure printing requires an additional coating or a larger amount of filler in the paper structure. Full article

Gravure printing is widely used in food, pharmaceutical, and other packaging industries. As a green printing material, water-based ink has problems such as non-volatile and poor drying on non-absorbent packaging substrates, which has a great impact on its application. To solve these difficulties, this study adopts the volume of fluid (VOF) method and user-defined function (UDF) to establish a multiphase flow impinging air jets drying model of water-based ink in the gravure printing process, taking a water-based ink droplet as an example. The model was used to simulate the ink drying state in the impinging air jets region and analyze the effects of impinging air jets’ temperature and velocity, as well as ink viscosity and thickness, on the ink drying efficiency. Meanwhile, the heat and mass transfer mechanism between impinging air jets and water-based ink was investigated. The results show that the higher impinging air jet temperature and velocity, the faster the drying rate of the ink; a lower viscosity and thinner thickness of ink can also enhance the drying efficiency of the ink. The multiphase impinging air jets drying model based on the computational fluid dynamics (CFD) method provides a new research idea for the analysis of drying characteristics of water-based ink on non-absorbent substrates, and the research results provide theoretical support to promote its application. Full article

Aimed at the growing interest in printed batteries, widely used industrial gravure printing was recently proven to be able to produce high-quality electrodes for lithium-ion batteries (LiBs), demonstrating its utility in the study of new functional materials. Here, for the first time, gravure printing was investigated for the mass production of well-known low-cost graphite-based anodes for LiBs. Graphite was also chosen as a case study to explore the influence of process parameters on the layer microstructure and the performance of the printed anodes. In particular, upon decreasing the size of the active material nanoparticles through ball-milling, an enhancement in anode performance was observed, which is related to an improvement in the material distribution in the printed layer, even in the case of increasing mass loading through a multilayer approach. A further improvement in performance, close to the theoretical capacity, was possible by changing the ink parameters, obtaining a denser microstructure of the printed anode. Such good results further demonstrate the possibility of using gravure printing for the mass production of electrodes for printed batteries and, in general, components in the field of energy. Full article

Graphene/metal nanocomposites have shown a strong potential for use in electronic applications. In particular, the combination of silver nanowires (AgNWs) with graphene derivatives leads to the formation of an efficient conductive network, thus improving the electrical properties of a composite. This work focused on developing highly conductive hydrophilic hybrids of simultaneously functionalized and reduced graphene oxide (f-rGO) and AgNWs in different weight ratios by following two different synthetic routes: (a) the physical mixture of f-rGO and AgNWs, and (b) the in situ reduction of GO in the presence of AgNWs. In addition, the role of AgNWs in improving the electrical properties of graphene derivatives was further examined by mixing AgNWs with a hybrid of few-layered graphene with functionalized multiwalled carbon nanotubes (FLG/MWNT-f-OH). The studied materials showed a remarkable improvement in the overall electrical conductivity due to the synergistic effect of their components, which was proportional to the percentage of Ag and dependent on the procedure of the hybrid formation. One of the f-rGO/AgNWs composites was also selected for the preparation of gravure printing inks that were tested to determine their rheological and printing properties. All of the f-rGO/AgNWs composites were shown to be very promising materials for use as conductive inks for flexible electronics. Full article

It is a common practice to add rheology modifiers to functional inks, such as graphene inks, to optimize the rheological properties so that they can be printed with a certain printing technique. This practice may lead to inks formulations with poorer electrical, optical, and mechanical performance upon its application, which are of paramount importance in printed electronics. In this study, we demonstrate for three different commercial graphene-based inks that it is possible to control the amount of ink transferred to the flat surface by tweaking printing parameters, such as the velocity and the length scale of the gravure cell, without modifying the rheology of the ink. Finally, the results are summarized in printing maps based on dimensionless numbers, namely, the capillary and Reynolds numbers. Full article

Gravure printing, which is a roll-to-roll printed electronics system suitable for high-speed patterning of functional layers have advantages of being applied to flexible webs in large areas. As each of the printing procedure from inking to doctoring followed by ink transferring and setting influences the quality of the pattern geometry, it is necessary to detect and diagnose factors causing the printing defects beforehand. Data acquisition with three triaxial acceleration sensors for fault diagnosis of four major defects such as doctor blade tilting fault was obtained. To improve the diagnosis performances, optimal sensor selection with Sensor Data Efficiency Evaluation, sensitivity evaluation for axis selection with Directional Nature of Fault and feature variable optimization with Feature Combination Matrix method was applied on the raw data to form a Smart Data. Each phase carried out on the raw data progressively enhanced the diagnosis results in contents of accuracy, positive predictive value, diagnosis processing time, and data capacity. In the case of doctor blade tilting fault, the diagnosis accuracy increased from 48% to 97% with decreasing processing time of 3640 s to 16 s and the data capacity of 100 Mb to 5 Mb depending on the input data between raw data and Smart Data. Full article