Inkjet-printed micro-patterns on hydrophobic surfaces have promising applications in the fabricat... more Inkjet-printed micro-patterns on hydrophobic surfaces have promising applications in the fabrication of microscale devices such as organic thin-film transistors. The low wettability of the surface prevents the inkjet-printed droplets from spreading, connecting to each other, and forming a pattern. Consequently, it is challenging to form micro-patterns on surfaces with low wettability. Here, we propose a sequential printing and drying method to form micro-patterns and control their shape. The first set of droplets is inkjet-printed at a certain spacing and dried. The second set of droplets is printed between these dry anchors on the surface with low wettability. As a result, a stable bridge on the surface with low wettability forms. This printing method is extended to more complicated shapes such as triangles. By implementing an energy minimization technique, a simple model was devised to predict the shape of the inkjet-printed micro-patterns while confirming that their equilibrium s...
Body: Printed electronics is an inexpensive way of producing electronic devices for every-day app... more Body: Printed electronics is an inexpensive way of producing electronic devices for every-day applications such as flexible biosensors, affordable RFID price tags and large-area optoelectronics. Transistors are the most fundamental components of many digital and analog circuits. Printed organic thin-film transistors (OTFT) consist of different functional layers deposited from solution. The conductive electrodes are commonly printed using metal nanoparticles that need to be sintered to become conductive. These electrodes are usually printed on other previously solution-processed layers. However, annealing the electrodes will impose another annealing step on the previously deposited layers. Depending on the chemical structure of these layers, their surface or bulk might undergo changes that might affect the final device performance. In bottom-contact bottom-gate organic transistors, the source and drain electrodes are printed onto the gate dielectric layer, which will undergo the elec...
Hybrid organic/inorganic solar cells have been fabricated and studied. The aim being to take adva... more Hybrid organic/inorganic solar cells have been fabricated and studied. The aim being to take advantage of the beneficial properties of both organic and inorganic materials. In this work we studied hybrid n-GaAs/Polymer photovoltaic devices and the effects of adding either carbon nanotubes or graphene into the polymer layer (either poly (3,4-ethyldioxythiophene):poly (styrenesulfunate) (PEDOT:PSS) or polyaniline (PANI)) to enhance its conductivity. We also investigated the use of two different metals (Al or Ag) as the anode electrode material to determine the influence of metal atoms migrating into the polymer layer on solar cell efficiency. The devices with the structure Al/PEDOT:PSS:MWCNT/n-GaAs/Au:Ge/Ni/Au exhibited the best performance, with a short circuit current (Jsc) of 28.6 mA/cm2 , an open circuit voltage (Voc) of 0.51 V, a fill factor (FF) of 29.8% and a power conversion efficiency (PCE) of 4.41% which is higher than other inorganic/organic hybrid devices reported in the literature. Based on optical absorption measurements and SEM analysis the solar cell performances reported here can mainly be attributed to photon absorption in both the doped PEDOT:PSS and the GaAs layers resulting in an increase of electron-hole pairs and improved the efficiency of the solar cells containing PEDOT:PSS in comparison with those containing PANI.
Structural Health Monitoring (SHM) uses sensors in advanced engineering structures to evaluate in... more Structural Health Monitoring (SHM) uses sensors in advanced engineering structures to evaluate integrity and detect damage or deformation affecting structural performance, e.g., cracks, holes, or corrosion. Carbon fiber textile composites are commonly used to reinforce structures such as aircraft, vehicles, or bridges due to their high tensile strength to weight ratio, chemical resistance, and thermal and electrical conductivity. Printing electronics on textiles is a scalable manufacturing technology combining the physical properties of textile materials with the added functionality of electronic elements making them self-sensing. Extrusion printing is a contactless digital printing method to print electrical conductors and passive circuit elements. This paper proposes to combine conventional carbon fiber composite manufacturing processes with printed conductors to create self-sensing carbon fiber textile composites. Damage is sensed by measuring resistance changes in a carbon fiber...
Inkjet printing is a promising technique for printed micro-electronics due to low cost, customiza... more Inkjet printing is a promising technique for printed micro-electronics due to low cost, customizability and compatibility with large-area, flexible substrates. However, printed line shapes can suffer from bulges at the start of lines and at corner points in 2D line patterns. The printed pattern can be multiple times wider than the designed linewidth. This can severely impact manufacturing accuracy and achievable circuit density. Bulging can be difficult to prevent without changing the ink-substrate-system, the drying conditions or the circuit design, all of which can be undesirable. Here, we demonstrate a novel printing methodology that solves this issue by changing the order in which drops are placed on the substrate. The pattern is split up into segments of three drops where the central drop is printed last. This symmetric printing prevents the unwanted ink flow that causes bulging. Larger bulge-free patterns are created by successively connecting segments. Line formation in both ...
Inkjet-printed micro-patterns on hydrophobic surfaces have promising applications in the fabricat... more Inkjet-printed micro-patterns on hydrophobic surfaces have promising applications in the fabrication of microscale devices such as organic thin-film transistors. The low wettability of the surface prevents the inkjet-printed droplets from spreading, connecting to each other, and forming a pattern. Consequently, it is challenging to form micro-patterns on surfaces with low wettability. Here, we propose a sequential printing and drying method to form micro-patterns and control their shape. The first set of droplets is inkjet-printed at a certain spacing and dried. The second set of droplets is printed between these dry anchors on the surface with low wettability. As a result, a stable bridge on the surface with low wettability forms. This printing method is extended to more complicated shapes such as triangles. By implementing an energy minimization technique, a simple model was devised to predict the shape of the inkjet-printed micro-patterns while confirming that their equilibrium s...
Body: Printed electronics is an inexpensive way of producing electronic devices for every-day app... more Body: Printed electronics is an inexpensive way of producing electronic devices for every-day applications such as flexible biosensors, affordable RFID price tags and large-area optoelectronics. Transistors are the most fundamental components of many digital and analog circuits. Printed organic thin-film transistors (OTFT) consist of different functional layers deposited from solution. The conductive electrodes are commonly printed using metal nanoparticles that need to be sintered to become conductive. These electrodes are usually printed on other previously solution-processed layers. However, annealing the electrodes will impose another annealing step on the previously deposited layers. Depending on the chemical structure of these layers, their surface or bulk might undergo changes that might affect the final device performance. In bottom-contact bottom-gate organic transistors, the source and drain electrodes are printed onto the gate dielectric layer, which will undergo the elec...
Hybrid organic/inorganic solar cells have been fabricated and studied. The aim being to take adva... more Hybrid organic/inorganic solar cells have been fabricated and studied. The aim being to take advantage of the beneficial properties of both organic and inorganic materials. In this work we studied hybrid n-GaAs/Polymer photovoltaic devices and the effects of adding either carbon nanotubes or graphene into the polymer layer (either poly (3,4-ethyldioxythiophene):poly (styrenesulfunate) (PEDOT:PSS) or polyaniline (PANI)) to enhance its conductivity. We also investigated the use of two different metals (Al or Ag) as the anode electrode material to determine the influence of metal atoms migrating into the polymer layer on solar cell efficiency. The devices with the structure Al/PEDOT:PSS:MWCNT/n-GaAs/Au:Ge/Ni/Au exhibited the best performance, with a short circuit current (Jsc) of 28.6 mA/cm2 , an open circuit voltage (Voc) of 0.51 V, a fill factor (FF) of 29.8% and a power conversion efficiency (PCE) of 4.41% which is higher than other inorganic/organic hybrid devices reported in the literature. Based on optical absorption measurements and SEM analysis the solar cell performances reported here can mainly be attributed to photon absorption in both the doped PEDOT:PSS and the GaAs layers resulting in an increase of electron-hole pairs and improved the efficiency of the solar cells containing PEDOT:PSS in comparison with those containing PANI.
Structural Health Monitoring (SHM) uses sensors in advanced engineering structures to evaluate in... more Structural Health Monitoring (SHM) uses sensors in advanced engineering structures to evaluate integrity and detect damage or deformation affecting structural performance, e.g., cracks, holes, or corrosion. Carbon fiber textile composites are commonly used to reinforce structures such as aircraft, vehicles, or bridges due to their high tensile strength to weight ratio, chemical resistance, and thermal and electrical conductivity. Printing electronics on textiles is a scalable manufacturing technology combining the physical properties of textile materials with the added functionality of electronic elements making them self-sensing. Extrusion printing is a contactless digital printing method to print electrical conductors and passive circuit elements. This paper proposes to combine conventional carbon fiber composite manufacturing processes with printed conductors to create self-sensing carbon fiber textile composites. Damage is sensed by measuring resistance changes in a carbon fiber...
Inkjet printing is a promising technique for printed micro-electronics due to low cost, customiza... more Inkjet printing is a promising technique for printed micro-electronics due to low cost, customizability and compatibility with large-area, flexible substrates. However, printed line shapes can suffer from bulges at the start of lines and at corner points in 2D line patterns. The printed pattern can be multiple times wider than the designed linewidth. This can severely impact manufacturing accuracy and achievable circuit density. Bulging can be difficult to prevent without changing the ink-substrate-system, the drying conditions or the circuit design, all of which can be undesirable. Here, we demonstrate a novel printing methodology that solves this issue by changing the order in which drops are placed on the substrate. The pattern is split up into segments of three drops where the central drop is printed last. This symmetric printing prevents the unwanted ink flow that causes bulging. Larger bulge-free patterns are created by successively connecting segments. Line formation in both ...
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Papers by Paria Naderi