Direct Printing Method Research Articles

Laser trimming of graphene oxide for functional photonic applications

This article reviews the recent photonic applications on graphene oxide and reduced graphene oxide films via the direct laser printing method. Attention has been paid to the unique optical property modulations of graphene oxide films during the laser reduction process, which enable a wide range of functional photonic and optoelectronic devices. The exotic properties of graphene oxide during the laser reduction process, including the tunable dispersion relation, flexible patterning capability, surface functionalization possibility, wavefront shaping ability, and the mechanical robustness and strength, make it a promising integratable platform for the next-generation ultrathin, light-weight and flexible photonic and optoelectronic applications.

Direct inkjet printing of miniaturized luminescent YAG:Er3+ from sol-gel precursor

This work focuses on demonstrating the fabrication of miniaturized scintillators based on rare earth activated YAG ceramics using the direct inkjet printing method. Erbium was chosen as the activator, and YAG sol-gel precursor inks were prepared under precise hydrolysis and polycondensation reactions. The precursors showed excellent control over rheology and surface tension, resulting in good printability. One of the most important challenges of inkjet printing of lines is the stability of lines. Line stability during printing is highly dependent on the printing frequency, drop spacing and substrate temperature. When a line was printed drop by drop, bulges were always observed during printing at 25 °C. This instability was significantly suppressed when the substrates were slightly heated. Adding polyvinylpyrrolidone to the precursor helped eliminate pores and cracks during firing. Crack-free YAG lines with ∼200 nm thickness were obtained after firing. The photoluminescence of YAG:Er heat-treated at 1200 °C for 1 h was optimized for an Er concentration of 2 wt%. X-ray induced radioluminescence was dominated by emission lines at 398 and 567 nm.

Flexible and Stretchable Supercapacitors from Carbon Materials

Flexible and stretchable electronics have attracted increasing attention over the past decade. Compared with traditional electronics, which based on rigid silicon chips, flexible and stretchable electronics can conform to complex surfaces and sustain large deformations without sacrificing their performance. An important component of flexible or stretchable electronics is energy storage, such as supercapacitors or batteries. Existing stretchable supercapacitors are characterized by complicated fabrication processes, low stretchability and high cost, constraining their potential applications. Due to their electrical characteristics and large surface areas, carbon materials, such as activated carbon, carbon nanotubes, and graphene, have been investigated for supercapacitor applications. In this work, we report two new kinds of flexible and stretchable supercapacitors made from carbon nanotube and hybrid carbon materials using a facile and low-cost method. Stretchable electrodes were developed using vertically aligned carbon nanotube (CNT) forests grown on a silicon substrate by PECVD. The CNT forests were transferred to a prestretched elastomer substrate using a dry-transfer method. The CNT electrodes can be biaxially stretched up to 300% while maintaining good electrochemical performance. The area specific capacitance is enhanced almost 10x to more than 20mF/cm2. CNT forests can form novel micro- and nano- patterns under uniaxial or biaxial prestrains, making it possible to use them as conductive hierarchical scaffolds for functionalization with pseudocapacitive materials, such as MnO2 for better performance. Aerosol jet printing and self-organized origami were used to fabricate a stretchable RGO/CNT/PEDOT: PSS supercapacitor. The unique direct-printing method gives the supercapacitor outstanding mechanical properties. No delamination was observed at the interface between the printed film and the substrate during the large deformation process. The composite electrodes exhibited highly porous structures and high conductivity, which leads to good electrochemical performance: a large specific capacitance (150F/g), high rate capability (>95% at 5A/g compared to 0.1A/g), and high cyclability. Further, there was little performance degradation after hundreds of stretch-release cycles, indicating the excellent reliability of the stretchable devices. Our designs and methods open a new way for fabricating future energy storage devices with high deformability, high performance and low cost.

Inkjet-printed porphyrinic metal–organic framework thin films for electrocatalysis

A simple and effective direct inkjet printing method was developed to prepare porphyrinic metal–organic framework (MOF) thin films for electrocatalysis.

Direct Transfer Printing with Metal Oxide Layers for Fabricating Flexible Nanowire Devices

A direct printing method for fabricating devices by using metal oxide transfer layers instead of conventional transfer media such as polydimethylsiloxane is presented. Metal oxides are not damaged by organic solvents; therefore, electrodes with gaps less than 2 μm can be defined on a metal oxide transfer layer through photolithography. In order to determine a suitable metal oxide for use as transfer layer, the surface energies of various metal oxides are measured, and Au layers deposited on these oxides are transferred onto polyvinylphenol (PVP). To verify the feasibility of our approach, Au source–drain electrodes on transfer layers and Si nanowires (NWs) addressed by the dielectrophoretic (DEP) alignment process are transferred onto rigid and flexible PVP‐coated substrates. Based on transfer test and DEP process, Al2O3 is determined to be the best transfer layer. Finally, Si NWs field effect transistors (FETs) are fabricated on a rigid Si substrate and a flexible polyimide film. As the channel length decreases from 3.442 to 1.767 μm, the mobility of FET on the Si substrate increases from 127.61 ± 37.64 to 181.60 ± 23.73 cm2 V−1 s−1. Furthermore, the flexible Si NWs FETs fabricated through this process show enhanced electrical properties with an increasing number of bending cycles.

Low cost commercial high-efficiency selective emitter solar cells with non-busbar inkjet printing pattern

The direct inkjet printing method involves the deposition of a wax droplet onto a wafer surface. Wax is used as a resistance layer during etch-back wet process, which coats on top of the dielectric surface with the same Ag electrode printing pattern. Drop on demand (DOD) inkjet printing selective emitter (SE) process has higher performance but more cost because of the additional raw materials, we need to balance the cost of wax exhaust and the efficiency rise. In this paper, we report a sort of new inkjet wax printing pattern, except at the busbar location which has the same printing pattern with the normality.We tested the cell infrared ray response (IR), module power and module electroluminescence (EL), in contrast to the normal inkjet printing pattern cell we found there is no any abnormal phenomenon for the new inkjet printing pattern cell near bus-bar area. Furthermore, the conversion efficiency is comparable in the mass production environment.

Fabrication of catalyst coated membrane with screen printing method in a proton exchange membrane fuel cell

A new proton exchange membrane fuel cell catalyst paste based on direct screen printing was developed to fabricate membrane electrode assembly (MEA) with catalyst coated membrane (CCM) technique. A mixture of cyclohexanol and ethylene glycol was found to be the best solvent for the screen printing catalyst paste in terms of avoiding the swelling of K+ form Nafion® membrane and mud-cracking in the catalyst layer during the CCM-MEA fabrication process and improving adhesion between the Nafion® membrane and catalyst layers. The CCM-MEAs fabricated with this new catalyst paste with the direct screen printing method showed better or comparable performance with the same or much less catalyst loading compared with that of MEA fabricated with a gas diffusion electrode (GDE) technique. An empirical relationship was provided to determine the amount of solvents used for the catalyst paste. Criteria were also proposed to choose the potentially suitable solvents. The other factors which might affect the performance of the screen printed CCM-MEAs were also examined. The low cell voltage decay rate and the relatively high performance of the screen printed CCM-MEAs demonstrated that the direct screen printing method with the proposed new catalyst paste could be a beneficial complement to the conventional CCM fabrication technique.

Fabrication of a wafer-scale uniform array of single-crystal organic nanowire complementary inverters by nanotransfer printing

Abstract We report the fabrication and electrical characterization of a wafer-scale array of organic complementary inverters using single-crystal 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-PEN) and fullerene (C60) nanowires as p- and n-channels, respectively. Two arrays of single-crystal organic nanowires were generated consecutively on desired locations of a common substrate with a desired mutual alignment by a direct printing method (liquid-bridge-mediated nanotransfer molding). Another direct printing of silver micron scale structures, as source and drain electrodes, on the substrate with the two printed nanowire arrays produced an array of complementary inverters with a bottom gate, top contact configuration. Field-effect mobilities of single-crystal TIPS-PEN and C60 nanowire field-effect transistors (FETs) in the arrays were uniform with 1.01 ± 0.14 and 0.10 ± 0.01 cm2V−1 s−1, respectively. A wafer-scale array of complementary inverters produced all by the direct printing method showed good performance with an average gain of 25 and with low variations among the inverters.

Direct transfer of magnetic sensor devices to elastomeric supports for stretchable electronics.

A novel fabrication method for stretchable magnetoresistive sensors is introduced, which allows the transfer of a complex microsensor systems prepared on common rigid donor substrates to prestretched elastomeric membranes in a single step. This direct transfer printing method boosts the fabrication potential of stretchable magnetoelectronics in terms of miniaturization and level of complexity, and provides strain-invariant sensors up to 30% tensile deformation.

Plasmon-enhanced photoelectrochemical water splitting with size-controllable gold nanodot arrays.

Size-controllable Au nanodot arrays (50, 63, and 83 nm dot size) with a narrow size distribution (± 5%) were prepared by a direct contact printing method on an indium tin oxide (ITO) substrate. Titania was added to the Au nanodots using TiO(2) sols of 2-3 nm in size. This created a precisely controlled Au nanodot with 110 nm of TiO(2) overcoats. Using these precisely controlled nanodot arrays, the effects of Au nanodot size and TiO(2) overcoats were investigated for photoelectrochemical water splitting using a three-electrode system with a fiber-optic visible light source. From UV-vis measurement, the localized surface plasmon resonance (LSPR) peak energy (ELSPR) increased and the LSPR line width (Γ) decreased with decreasing Au nanodot size. The generated plasmonic enhancement for the photoelectrochemical water splitting reaction increased with decreasing Au particle size. The measured plasmonic enhancement for light on/off experiments was 25 times for the 50 nm Au size and 10 times for the 83 nm Au nanodot size. The activity of each catalyst increased by a factor of 6 when TiO2 was added to the Au nanodots for all the samples. The activity of the catalyst was proportional to the quality factor (defined as Q = E(LSPR)/Γ) of the plasmonic metal nanostructure. The enhanced water splitting performance with the decreased Au nanodot size is probably due to more generated charge carriers (electron/hole pair) by local field enhancement as the quality factor increases.

Improving Gravure Plate-Making Method to Printing Transparent Conductive Film

The metal grid transparent conductive film is a kind of important electronic material. The production method is a valuable topic. Gravure printing, as one direct-printing method, is suitable for printing the metal grid transparent conductive film, according to gravure printing principle. This paper focuses on improving gravure plate to print the metal grid transparent conductive film. Firstly, the nano-sliver grid transparent conductive film is printed by electronic engraving plate and laser ablation plate. Then, according to the analysis result that the resistivity of the nano-sliver grid transparent conductive film printed by two general plates is too high to meet the requirements of the transparent conductive film, the general plate-making methods is improved to make the new gravure plate. Last, the metal grid transparent conductive film, with relatively high light transmittance and low resistivity which meet the requirements of the transparent conductive film , is printed by the improved plate.

Luminescent gold surfaces for sensing and imaging: patterning of transition metal probes.

Luminescent transition metal complexes are introduced for the microcontact printing of optoelectronic devices. Novel ruthenium(II), RubpySS, osmium(II), OsbpySS, and cyclometalated iridium(III), IrbpySS, bipyridyl complexes with long spacers between the surface-active groups and the metal were developed to reduce the distance-dependent, nonradiative quenching pathways by the gold surface. Indeed, surface-immobilized RubpySS and IrbpySS display strong red and green luminescence, respectively, on planar gold surfaces with luminescence lifetimes of 210 ns (RubpySS·Au) and 130 and 12 ns (83%, 17%) (IrbpySS·Au). The modified surfaces show enhancement of their luminescence lifetime in comparison with solutions of the respective metal complexes, supporting the strong luminescence signal observed and introducing them as ideal inorganic probes for imaging applications. Through the technique of microcontact printing, complexes were assembled in patterns defined by the stamp. Images of the red and green patterns rendered by the RubpySS·Au and IrbpySS·Au monolayers were revealed by luminescence microscopy studies. The potential of the luminescent surfaces to respond to biomolecular recognition events is demonstrated by addition of the dominant blood-pool protein, bovine serum albumin (BSA). Upon treatment of the surface with a BSA solution, the RubpySS·Au and IrbpySS·Au monolayers display a large luminescence signal increase, which can be quantified by time-resolved measurements. The interaction of BSA was also demonstrated by surface plasmon resonance (SPR) studies of the surfaces and in solution by circular dichroism spectroscopy (CD). Overall, the assembly of arrays of designed coordination complexes using a simple and direct μ-contact printing method is demonstrated in this study and represents a general route toward the manufacture of micropatterned optoelectronic devices designed for sensing applications.

Multi-functional SiO2 moth-eye pattern for photovoltaic applications

A moth-eye pattern made of silica (SiO2) nanoparticles mixed with MIBK (methyl isobutyl ketone) was fabricated on a glass substrate using a direct printing method. The patterned glass was annealed to improve hardness and a heptdecafluoro-1,1,2,2-tetrahydrodecyl trichloro-silane based self-assembled monolayer (HDFS-SAM) was applied to the moth-eye pattern to reduce surface energy which improves hydrophobic properties. Compared to flat glass, the moth-eye patterned glass with a HDFS-SAM coating showed reduced reflectance, strong hardness, and high efficiency. As a result, the JSC of photovoltaic module was increased up to 1.9755mA/cm2 and efficiency was improved by 4.66% by the increased current density (JSC) of photovoltaic system, and the external quantum efficiency was enhanced over the entire visible spectrum.

Fabrication of Vertical Organic Junction Transistor by Direct Printing Method

An organic junction transistor with a vertical structure based on an active layer of poly(3-hexylthiophene) was fabricated by facile micro-contact printing combined with the Langmuir-Schaefer technique, without conventional e-beam or photo-lithography. Direct printing and subsequent annealing of Au-nanoparticles provided control over the thickness of the Au electrode and hence control of the electrical contact between the Au electrode and the active layer, ohmic or Schottky. The junction showed similar current-voltage characteristics to an NPN-type transistor. Current through the emitter was simply controllable by the base voltage and a high transconductance of ~0.2 mS was obtained. This novel fabrication method can be applied to amplifying or fast switching organic devices.

Fabrication of Diverse-Scale Patterned Layer on Organic Photovoltaics

In order to increase the conversion efficiency of organic photovoltaics (OPV), diverse-scale patterns were formed on a glass substrate using the direct printing technique. The optical properties of the patterns depended on the size, shape, height, and pitch of the patterns. Randomly distributed nano- and micro-patterns caused light scattering, which increased the diffusion transmittance. The other pattern, which was a nano-sized anti-reflective pattern comprising a 300 nm sized hexagonal array, decreased the reflectance of light on the surface. The optical properties of these patterns, can be used to improve solar cell efficiency by increasing the light allowed onto the light-absorbing layer. We used a direct printing method with a poly(dimethylsiloxane) (PDMS) mold to fabricate these patterns on glass substrates. These patterns were transferred from PDMS to the surface of a glass substrate. Hydrogen silsesquioxane (HSQ) was used as a resin since its properties include volatility and allow for spin-coating; it also has a reflective index similar to that of glass. This method has low cost and a simple process compared to optic-based lithography. After these patterns were formed outside the glass substrate, a conductive polymer layer and the active layer were formed by spin-coating, and the cathode was deposited by a thermal evaporator. The electrical properties of solar cells fabricated with these patterns on their surfaces were measured with a solar simulator. The conversion efficiency of the solar cells with these surface patterns showed an increase of up to 6.8% in comparison with conventional cells.

High‐Performance Air‐Stable Single‐Crystal Organic Nanowires Based on a New Indolocarbazole Derivative for Field‐Effect Transistors

A new indolocabazole derivative possessing an extended aromatic core and solubilizing long aliphatic chains effectively self-assembles and crystallizes within the nanoscale channels to form single-crystal nanowires via a direct printing method from an ink solution. Single-crystal organic nanowire transistor arrays based on the π-extended indolocarbazole derivative exhibit an excellent hole mobility of 1.5 cm² V⁻¹ s⁻¹ and outstanding environmental stability.

Fine-Pitch Copper Wiring Formed with Super-Inkjet and Oxygen Pump

We have successfully printed wires of 5 µm line widths and spaces in copper nanoparticle ink with a super-inkjet printer. The wires show resistivity as low as 8.1 µΩ·cm after sintering at 250 °C in an extremely low oxygen atmosphere generated by an oxygen pump. To our knowledge, this is the first report of micron-scale copper wiring formed by a direct printing method without any masks or templates.

Single‐Crystal Organic Nanowire Electronics by Direct Printing from Molecular Solutions

AbstractA one‐step process to generate single‐crystal organic nanowire arrays using a direct printing method (liquid‐bridge‐mediated nanotransfer molding) that enables the simultaneous synthesis, alignment, and patterning of nanowires from molecular ink solutions is reported. Using this method, many single‐crystal organic nanowires can easily be synthesized by self‐assembly and crystallization of organic molecules within the nanoscale channels of molds, and these nanowires can then be directly transferred to specific positions on substrates to generate nanowire arrays by a direct printing process. The position of the nanowires on complex structures is easy to adjust, because the mold is movable on the substrates before the polar liquid layer, which acts as an adhesive lubricant, is dried. Repeated application of the direct printing process can be used to produce organic nanowire‐integrated electronics with two‐ or three‐dimensional complex structures on large‐area flexible substrates. This efficient manufacturing method is used to fabricate high‐performance organic nanowire field‐effect transistors that are integrated into device arrays, inverters, and phototransistors on flexible plastic substrates.

Statistical Manufacturing Model of Printing Technology

There has been an evident increase in the demand for accurate and complex patterns for particles used in microsized electronic devices. Direct printing technology has been promoted as a solution for these needs, as the development of this technology provides both economical and environmental benefits, as well as being a time and energy saving process. Research in the field of printing technologies is still in the initial stages, involving the study of physical and chemical properties of printing materials. There are several methods currently using direct printing methods: microdispensing deposition write (MDDW), maskless mesoscale materials deposition (M3D), and inkjet printing. This study explores the direct printing methods of sequential and randomized printing associated with MDDW, M3D, and inkjet printing using computer simulations compared with actual experimentations. Sequential printing involves depositing particles onto the substrate in a specific order based on particle size. This method is associated with MDDW, where a relatively high viscous ink is dispensed onto the substrate so that particle sizes maintain an order in relation to one another, effectively producing a higher packing factor. Randomized printing involves the dispensing of various sizes of particles onto the substrate in a random order, as in inkjet printing. With this process, the probability of obtaining an efficient packing factor is unlikely and decreases even more with particle size. Therefore, the monolayer method, involving the deposition of individual particles, was developed to increase the packing factor when using the inkjet process. The results presented in this study proved that monolayering methods coincide with the projections predicted by the computer simulation. Sequential packing (MDDW) provides a shorter and higher range of packing factors than that of random packing sequences (ink jet); thus showing sequential packing to be the more efficient method. Sequential packing is closely related to the printing of high viscosity ink because of the higher packing factor that this method provides. An ink with increased viscosity allows for better conductivity which is essential in the development of improved nanoprinting technologies. This study provides evidence for the most efficient means of increasing the packing factor of particles; these methods offer the opportunity for technological advancement and commercialization of nanoprinting materials.

Laser Printing of Organic Electronics and Sensors

This work presents the use of the Laser-Induced Forward Transfer (LIFT) process as an advanced tool for organic electronics and biosensor fabrication. LIFT is an alternative micro-patterning technology that employs pulsed laser irradiation for the selective deposition of a liquid or solid target material onto a receiving substrate. LIFT) is a non-contact direct printing method that can deposit patterns of functional materials, in liquid or in solid phase, including organic, carbon-based nanomaterials, biological compounds, metal nanoparticles, and dielectrics on different substrates including flexible materials. More specifically, the LIFT process is used for direct printing of Agbased nanoparticles, organic semiconducting materials for organic transistors and biomaterials (enzymes and photosynthetic proteins) for environmental biosensor fabrication. The use of LIFT has shown the possibility of direct immobilization of biomaterials onto the surface of the sensors without the use of chemical linkers.