This work was partially supported by a Grant-in-Aid for Scientific Research (No. 24225003). This work was supported financially by the JX Nippon Oil &#38; Energy Corporation.

1. Preparation of Active Layer Solutions
<ol>
	<li>Active layer solution for the amine doped PFD devices 
	NOTE: The PFD, 4,4&#39;,4&#39;&#39;-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA), 9,9-dimethyl-N,N&#39;-di(1-naphthyl)-N,N&#39;-diphenyl-9H-fluorene-2,7-diamine (DMFL-NPB), Poly(ethylene oxide) (PEO), were used as received. The potassium trifluoromethanesulfonate (K2CF3SO3) was dried under vacuum at 200 &#176;C for 1 hr prior to use.
	<ol>
		<li>For the devices having a PFD:amine ratio of 1:0.25, dissolve 10 mg of PFD and 2.5 mg of the aromatic amine in 1 ml of chloroform and stir for 1 hr at 40 &#176;C. For those having a PFD:amine ratio of 1:1, use 10 mg of the aromatic amine.</li>
		<li>Separately, dissolve 10 mg of PEO in 1 ml of cyclohexanone and stir for 1 hr at 60 &#176;C, and dissolve 2.5 mg of potassium trifluoromethanesulfonate (KCF3SO3) in 1 ml of cyclohexanone and stir for 1 hr at 40 &#176;C.</li>
		<li>Add 0.78 ml of the PEO solution and 0.147 ml of the KCF3SO3 solution to the PFD solution using micropipettes. Stir the mixed solution for 4 hr at 40 &#176;C.</li>
		<li>Filter the mixed solution using a membrane filter prior to spin coating.</li>
	</ol>
	</li>
	<li>Active layer solution for the undoped PFD device
	<ol>
		<li>For the undoped PFD device, dissolve 10 mg of PFD in 1 ml of chloroform and stir for 1 hr at 40 &#176;C. The steps which follow are the same as those described previously for the amine doped PFDs in 1.1.2 - 1.1.4.</li>
	</ol>
	</li>
</ol>
2. Fabrication of LEC Devices
NOTE: Fabrication process of LEC devices is summarized in Figure 1.
<ol>
	<li>Ultrasonically clean patterned indium-tin oxide (ITO) glass substrates with diluted detergent, followed by ionized water, acetone and 2-propanol using a desktop ultrasonic bath (38 kHz) for 3 min for each step. Finally, remove the solvent using an N2 blower.</li>
	<li>Treat the substrates with UV/O3 for 3 min using a UV/O3 treating unit according to manufacturer&#39;s protocol. Perform the active layer coating process under an inert atmosphere in a glove box.</li>
	<li>Set a cleaned substrate on the head of a spin coater. Dispense around 100 &#181;l of the active layer solution using a micropipette. Spin the substrate as follows: 800 rpm for 60 sec, increase the rate to 1,000 rpm over 3 sec, then spin at 1,000 rpm for 10 sec. The active layer thickness will be around 150 nm.</li>
	<li>Dry the coated substrates in the glove box overnight.</li>
	<li>Wipe off excess polymer to ensure a proper electrode connection and encapsulation.</li>
	<li>Place the substrates on an evaporation holder for deposition of aluminum. Load the holder in the evaporation chamber, and thermally deposit a 100 nm layer of aluminum at an evaporation rate of 0.4 nm/sec through a stainless steel evaporation mask, which has 3 mm wide openings for depositing the aluminum counter electrodes.</li>
	<li>When deposition is complete, transfer the devices to a glove box under an inert atmosphere. Apply a bead of UV curable epoxy resin in the shape of a rectangle using a dispenser. Place a cover glass (15 mm x 12 mm x 0.7 mm-thick) on the resin to encapsulate the device (see Figure 1).</li>
	<li>Cure the resin using UV radiation (cumulative dose: 6,000 mJ/cm2, wavelength: 365 nm) from a UV-LED light source.</li>
</ol>
3. Characterization
<ol>
	<li>J-V-L measurements 
	NOTE: The current density (J)-voltage (V)-luminance (L) (J-V-L) characteristics and Commission Internationale de l&#39;Eclairage (CIE) coordinates were measured using a spectral photo detector equipped with a DC voltage current source monitor. The measurement system is controlled by a PC with a custom control software for data acquisition. The system was calibrated following manufacturer&#39;s protocol and measurements were performed in the dark under a black curtain.
	<ol>
		<li>Connect the terminals to the contacts of the device with alligator clips. Place the device on the measurement stage.</li>
		<li>Run the control software for data acquisition. The system controls the applied voltage and current over time and collects the emission spectra by the spectrometer through an optical fiber.</li>
	</ol>
	</li>
</ol>

<ol>
	<li>Pei, Q., Yu, G., Zhang, C., Yang, Y., Heeger, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymer+light-emitting+electrochemical+cells.">Polymer light-emitting electrochemical cells.</a> Science. 269 (5227), 1086-1088 (1995).</li><li>Sun, Q., Li, Y., Pei, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymer+light-emitting+electrochemical+cells+for+high-efficiency+low-voltage+electroluminescent+devices.">Polymer light-emitting electrochemical cells for high-efficiency low-voltage electroluminescent devices.</a> J. Disp. Technol. 3 (2), 211-224 (2007).</li><li>Meier, S. B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-emitting+electrochemical+cells:+recent+progress+and+future+prospects.">Light-emitting electrochemical cells: recent progress and future prospects.</a> Mater. Today. 17 (5), 217-223 (2014).</li><li>Edman, L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Single-component+light-emitting+electrochemical+cell+fabricated+from+cationic+polyfluorene:+Effect+of+film+morphology+on+device+performance.">Single-component light-emitting electrochemical cell fabricated from cationic polyfluorene: Effect of film morphology on device performance.</a> J. Appl. 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Photonics. 7 (10), 817-824 (2013).</li><li>Yang, Y., Pei, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+blue-green+and+white+light-emitting+electrochemical+cells+based+on+poly+9,+9-bis+(3,+6-dioxaheptyl)-fluorene-2,+7-diyl.">Efficient blue-green and white light-emitting electrochemical cells based on poly 9, 9-bis (3, 6-dioxaheptyl)-fluorene-2, 7-diyl.</a> J. Appl. Phys. 81 (7), 3294-3298 (1997).</li><li>Tang, S., Buchholz, H. A., Edman, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=White+Light+from+a+Light-Emitting+Electrochemical+Cell:+Controlling+the+Energy-Transfer+in+a+Conjugated+Polymer/Triplet-Emitter+Blend.">White Light from a Light-Emitting Electrochemical Cell: Controlling the Energy-Transfer in a Conjugated Polymer/Triplet-Emitter Blend.</a> ACS Appl. Mater. Iterfaces. 7 (46), 25955-25960 (2015).</li><li>Nishikitani, Y., Takizawa, D., Nishide, H., Uchida, S., Nishimura, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=White+Polymer+Light-Emitting+Electrochemical+Cells+Fabricated+Using+Energy+Donor+and+Acceptor+Fluorescent+&#960;-Conjugated+Polymers+Based+on+Concepts+of+Band-Structure+Engineering.">White Polymer Light-Emitting Electrochemical Cells Fabricated Using Energy Donor and Acceptor Fluorescent &#960;-Conjugated Polymers Based on Concepts of Band-Structure Engineering.</a> J. Phys. Chem. C. 119 (52), 28701-28710 (2015).</li><li>Sun, M., Zhong, C., Li, F., Cao, Y., Pei, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Fluorene&#8722;+Oxadiazole+Copolymer+for+White+Light-Emitting+Electrochemical+Cells.">A Fluorene&#8722; Oxadiazole Copolymer for White Light-Emitting Electrochemical Cells.</a> Macromolecules. 43 (4), 1714-1718 (2010).</li><li>Tang, S., Pan, J., Buchholz, H., Edman, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=White+Light-Emitting+Electrochemical+Cell.">White Light-Emitting Electrochemical Cell.</a> ACS Appl. Mater. Interfaces. 3 (9), 3384-3388 (2011).</li><li>Tang, S., Pan, J., Buchholz, H. 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The authors have nothing to disclose.

The LEC has an active layer containing hydrophobic PFD and aromatic amines, and hydrophilic polyethylene oxide and KCF3SO3. Because these materials have very different solubilities, careful preparation of the spin coating solution is critical to avoid incomplete solvation. Each must be first dissolved separately and completely in solvents with sufficient solvating ability, then the solutions are mixed together to form a uniform mixture. Balancing the exciton and exciplex emissions is key to obtainin...

Research and development of polymer light-emitting electrochemical cells (PLECs) have expanded in recent years.1-15 PLECs are similar to organic light-emitting diodes (OLEDs) in that both are surface emitting organic devices and are expected to find their way into future lighting applications. OLEDs are already on the market, but the cost is still high, one reason being that OLEDs need a complicated device structure with multiple layers. In contrast, PLECs have a very simple device structure which consists of a single active layer (emitting layer) between a pair of electrodes. This means that PLECs are suited to mass production processes such as roll-to-roll printing and coating. 
A PLEC has an active layer consisting of a fluorescent &#960;-conjugated polymer (FCP). The FCP can be electrochemically doped with a polymer electrolyte (a mixture of an ion conducting polymer and a salt). The FCP is p-doped on the anode side and n-doped on the cathode side during operation, and generates excitons which emit light between the p- and n-doped regions. Therefore, the emission color reflects the exciton emission (=fluorescence) wavelength of the FCP.
Stable white light emission is important for lighting applications, and color mixing techniques which employ two or more emitters have been widely used to achieve this.10-14 Recently, we presented a different approach for obtaining stable white light emission, using an active layer which contains blue-fluorescent poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFD) and &#960;-conjugated aromatic amines15. This white light emission comes from exciplexes formed between PFD and amine molecules in excited states. Exciplex emission has a broader spectrum compared to the exciton emission from the PDF and/or amines, which gives it a color close to that of natural light. This translates to a higher color rendering index (CRI), which is preferable for lighting applications.
In this article, the authors describe the procedure used to fabricate the exciplex based LECs and show the stability of their white light emission.

<table border="0" cellpadding="0" cellspacing="0" width="734">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:332px;">Poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFD)</td>
			<td style="width:99px;">Aldrich</td>
			<td style="width:115px;">571660</td>
			<td style="width:189px;"></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:332px;">4,4&#8217;,4&#8217;&#8217;-Tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA)</td>
			<td style="width:99px;">Aldrich</td>
			<td style="width:115px;">768669</td>
			<td style="width:189px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:332px;">9,9-Dimethyl-N,N&#8217;-di(1-naphthyl)-N,N&#8217;-diphenyl-9H-fluorene-2,7-diamine (DMFL-NPB)</td>
			<td style="width:99px;">Aldrich</td>
			<td style="width:115px;"></td>
			<td style="width:189px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:332px;">Poly(ethylene oxide) (PEO)</td>
			<td style="width:99px;">Aldrich</td>
			<td style="width:115px;">182028</td>
			<td style="width:189px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:332px;">Potassium tirifluoromethansulfonate (KCF3SO3)</td>
			<td style="width:99px;">Aldrich</td>
			<td style="width:115px;">422843</td>
			<td style="width:189px;">dried under vacuum at 200 &#176;C for 2 hr prior to use</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:332px;">Chloroform</td>
			<td style="width:99px;">Kanto Chemical Co.</td>
			<td style="width:115px;">08097-25</td>
			<td style="width:189px;">dehydrated</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:332px;">Cyclohexanone</td>
			<td style="width:99px;">Kanto Chemical Co.</td>
			<td style="width:115px;">07555-00</td>
			<td style="width:189px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:332px;">SCAT 20-X (detergent)</td>
			<td style="width:99px;">Daiichi Kogyo Seiyaku</td>
			<td style="width:115px;"></td>
			<td style="width:189px;">diluted with water</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:332px;">Acetone</td>
			<td style="width:99px;">Kanto Chemical Co.</td>
			<td style="width:115px;">01866-25</td>
			<td style="width:189px;">Electronic grage</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:332px;">2-propanol</td>
			<td style="width:99px;">Kanto Chemical Co.</td>
			<td style="width:115px;">32439-75</td>
			<td style="width:189px;">Electronic grage</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:332px;">13mm GD/X Disposable Filter Device PVDF Filter Media, Polypropylene Housing</td>
			<td style="width:99px;">Whatman</td>
			<td style="width:115px;">6872-1304</td>
			<td style="width:189px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:332px;">UV/O3 Treating Unit</td>
			<td style="width:99px;">SEN Lights Co.&#160;</td>
			<td style="width:115px;">SSP16-110</td>
			<td style="width:189px;"></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:332px;">Spectral Photo Detector</td>
			<td style="width:99px;">Otsuka Electronics</td>
			<td style="width:115px;">MCPD 9800</td>
			<td style="width:189px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:332px;">Voltage Current Source Monitor</td>
			<td style="width:99px;">&#160;ADCMT</td>
			<td style="width:115px;">6241A&#160;</td>
			<td style="width:189px;"></td>
		</tr>
		<tr height="168">
			<td height="168" style="height:168px;width:332px;">Evaporation Mask</td>
			<td style="width:99px;">&#160;Tokyo Process Service Co., Ltd.</td>
			<td style="width:115px;">NA</td>
			<td style="width:189px;">The evaporation mask was wet-etched to create openings for patterned deposition of aluminum. The size of the mask is 100 mm x 100 mm x 0.2 mm-thick.</td>
		</tr>
	</tbody>
</table>

fabrication of white light-emitting electrochemical cells with stable emission from exciplexes

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active layer which consists of blue-fluorescent poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFD) and &#960;-conjugated triphenylamine molecules. This white light emission originates from exciplexes formed between PFD and amines in electronically excited states. A device containing PFD, 4,4&#39;,4&#39;&#39;-tris[2-naphthyl(phenyl)amino]triphenylamine (2-TNATA), Poly(ethylene oxide) and K2CF3SO3 showed white light emission with Commission internationale de l&#39;&#233;clairage (CIE) coordinates of (0.33, 0.43) and a Color Rendering Index (CRI) of Ra = 73 at an applied voltage of 3.5 V. Constant voltage measurements showed that the CIE coordinates of (0.27, 0.37), Ra of 67, and the emission color observed immediately after application of a voltage of 5 V were nearly unchanged and stable after 300 sec.

The electroluminescence (EL) spectra were used to calculate the CIE coordinates and CRI values (Figures 2, 4, 5). Photographic images of the emitting devices were collected to verify the whiteness of the emission (Figure 3).
The EL spectra of the amine doped PFD devices and the undoped PFD device are shown in Figure 2. The undoped PFD device showed blue emission that corresponds...

Watch this Scientific Journal Video about Fabrication of White Light-emitting Electrochemical Cells with Stable Emission from Exciplexes at JoVE.com

Fabrication of White Light-emitting Electrochemical Cells with Stable Emission from Exciplexes

The authors present a method for fabricating stable white-light-emitting electrochemical cells utilizing emission from exciplexes formed between a blue-emitting fluorene polymer and aromatic amines.

The authors present an approach for fabricating stable white light emission from polymer light-emitting electrochemical cells (PLECs) having an active ...

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8.0K Views.  JX Nippon Oil & Energy Corporation. The authors present a method for fabricating stable white-light-emitting electrochemical cells utilizing emission from exciplexes formed between a blue-emitting fluorene polymer and aromatic amines.

Video: Fabrication of White Light-emitting Electrochemical Cells with Stable Emission from Exciplexes

Fabrication of VB2/Air Cells for Electrochemical Testing

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for synthesizing nanoscopic VB2 is presented as well as step-by-step procedure for applying a zirconium oxide coating to the VB2 particles for stabilization upon discharge. The process for disassembling existing zinc/air cells is shown, in addition construction of the new working electrode to replace the conventional zinc/air cell anode with a the nanoscopic VB2 anode. Finally, discharge of the completed VB2/air battery is reported. We show that using the zinc/air cell as a test bed is useful to provide a consistent configuration to study the performance of the high-energy high capacity nanoscopic VB2 anode.

Fabrication of VB2/Air Cells for Electrochemical Testing

A protocol is presented to study multi-electron metal/air battery systems by using previous technology developed for the zinc/air cell. Electrochemical testing is then performed on fabricated batteries to evaluate performance.

A technique to investigate the properties and performance of new multi-electron metal/air battery systems is proposed and presented. A method for ...

Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities

Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees of freedom to control electronic devices. In particular, the behavior of graphene&#8217;s charge carriers in response to potentials from charged Coulomb impurities is predicted to differ significantly from that of most materials. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) can provide detailed information on both the spatial and energy dependence of graphene&#39;s electronic structure in the presence of a charged impurity.&#160;The design of a hybrid impurity-graphene device, fabricated using controlled deposition of impurities onto a back-gated graphene surface, has enabled several novel methods for controllably tuning graphene&#8217;s electronic properties.1-8 Electrostatic gating enables control of the charge carrier density in graphene and the ability to reversibly tune the charge2 and/or molecular5 states of an impurity. This paper outlines the process of fabricating a gate-tunable graphene device decorated with individual Coulomb impurities for combined STM/STS studies.2-5 These studies provide valuable insights into the underlying physics, as well as signposts for designing hybrid graphene devices.

This paper details the fabrication process of a gate-tunable graphene device, decorated with Coulomb impurities for scanning tunneling microscopy studies. Mapping the spatially dependent electronic structure of graphene in the presence of charged impurities unveils the unique behavior of its relativistic charge carriers in response to a local Coulomb potential.

Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees ...

Fabrication of Low Temperature Carbon Nanotube Vertical Interconnects Compatible with Semiconductor Technology

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive thin-films. Due to the low growth temperature, the process allows integration with modern low-&#954; dielectrics and some flexible substrates. The process is compatible with standard semiconductor fabrication, and a method for the fabrication of electrical 4-point probe test structures for vertical interconnect test structures is presented. Using scanning electron microscopy the morphology of the CNT bundles is investigated, which demonstrates vertical alignment of the CNT and can be used to tune the CNT growth time. With Raman spectroscopy the crystallinity of the CNT is investigated. It was found that the CNT have many defects, due to the low growth temperature. The electrical current-voltage measurements of the test vertical interconnects displays a linear response, indicating good ohmic contact was achieved between the CNT bundle and the top and bottom metal electrodes. The obtained resistivities of the CNT bundle are among the average values in the literature, while a record-low CNT growth temperature was used.

A method for the growth of low temperature vertically-aligned carbon nanotubes, and the subsequent fabrication of vertical interconnect electrical test structures using semiconductor fabrication is presented.

We demonstrate a method for the low temperature growth (350 &#176;C) of vertically-aligned carbon nanotubes (CNT) bundles on electrically conductive ...

Indirect Fabrication of Lattice Metals with Thin Sections Using Centrifugal Casting

One of the typical methods to manufacture 3D lattice metals is the direct-metal additive manufacturing (AM) process such as Selective Laser Melting (SLM) and Electron Beam Melting (EBM). In spite of its potential processing capability, the direct AM method has several disadvantages such as high cost, poor surface finish of final products, limitation in material selection, high thermal stress, and anisotropic properties of parts. We propose a cost-effective method to manufacture 3D lattice metals. The objective of this study is to provide a detailed protocol on fabrication of 3D lattice metals having a complex shape and a thin wall thickness; e.g., octet truss made of Al and Cu alloys having a unit cell length of 5 mm and a cell wall thickness of 0.5 mm. An overall experimental procedure is divided into eight sections: (a) 3D printing of sacrificial patterns (b) melt-out of support materials (c) removal of residue of support materials (d) pattern assembly (e) investment (f) burn-out of sacrificial patterns (g) centrifugal casting (h) post-processing for final products. The suggested indirect AM technique provides the potential to manufacture ultra-lightweight lattice metals; e.g., lattice structures with Al alloys. It appears that the process parameters should be properly controlled depending on materials and lattice geometry, observing the final products of octet truss metals by the indirect AM technique.

An indirect additive manufacturing method combining a 3D printing of polymers with a centrifugal casting is outlined for manufacturing 3D octet truss metals (Al and Cu alloys) having a unit cell length of 5 mm with a wall thickness of 0.5 mm.

One of the typical methods to manufacture 3D lattice metals is the direct-metal additive manufacturing (AM) process such as Selective Laser Melting (SLM) ...

A Fabrication Method for Highly Stretchable Conductors with Silver Nanowires

Stretchable electronics are identified as a key technology for electronic applications in the next generation. One of the challenges in fabrication of stretchable electronic devices is the preparation of stretchable conductors with great mechanical stability. In this study, we developed a simple fabrication method to chemically solder the contact points between silver nanowire (AgNW) networks. AgNW nanomesh was first deposited on a glass slide via spray coating method. A reactive ink composed of silver nanoparticle (AgNPs) precursors was applied over the spray coated AgNW thin films. After heating for 40 min, AgNPs were preferentially generated over the nanowire junctions to solder the AgNW nanomesh, and reinforced the conducting network. The chemically modified AgNW thin film was then transferred to polyurethane (PU) substrates by casting method. The soldered AgNW thin films on PU exhibited no obvious change in electrical conductivity under stretching or rolling process with elongation strains up to 120%.

A simple synthesis method is used to chemically solder silver nanowire thin film to fabricate highly stretchable and conductive metal conductors.

Stretchable electronics are identified as a key technology for electronic applications in the next generation. One of the challenges in fabrication of ...

Emission Spectroscopic Boundary Layer Investigation during Ablative Material Testing in Plasmatron

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution for future high-speed reentry missions. But despite the advancements made since Apollo, heat flux prediction remains an imperfect science and engineers resort to safety factors to determine the TPS thickness. This goes at the expense of embarked payload, hampering, for example, sample return missions. 
Ground testing in plasma wind-tunnels is currently the only affordable possibility for both material qualification and validation of material response codes. The subsonic 1.2MW Inductively Coupled Plasmatron facility at the von Karman Institute for Fluid Dynamics is able to reproduce a wide range of reentry environments. This protocol describes a procedure for the study of the gas/surface interaction on ablative materials in high enthalpy flows and presents sample results of a non-pyrolyzing, ablating carbon fiber precursor. With this publication, the authors envisage the definition of a standard procedure, facilitating comparison with other laboratories and contributing to ongoing efforts to improve heat shield reliability and reduce design uncertainties.
The described core techniques are non-intrusive methods to track the material recession with a high-speed camera along with the chemistry in the reactive boundary layer, probed by emission spectroscopy. Although optical emission spectroscopy is limited to line-of-sight measurements and is further constrained to electronically excited atoms and molecules, its simplicity and broad applicability still make it the technique of choice for analysis of the reactive boundary layer. Recession of the ablating sample further requires that the distance of the measurement location with respect to the surface is known at all times during the experiment. Calibration of the optical system of the applied three spectrometers allowed quantitative comparison. At the fiber scale, results from a post-test microscopy analysis are presented.

Development of new ablative materials and their numerical modeling requires extensive experimental investigation. This protocol describes procedures for material response characterization in plasma flows with the core techniques being non-intrusive methods to track the material recession along with the chemistry in the reactive boundary layer by emission spectroscopy.

Ablative Thermal Protection Systems (TPS) allowed the first humans to safely return to Earth from the moon and are still considered as the only solution ...

Electrochemical Etching and Characterization of Sharp Field Emission Points for Electron Impact Ionization

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. The results of studies in which the etching current and the molarity of the NaOH solution used in the etching process were varied are presented. The investigation of the geometry of the tips, by imaging them with a scanning electron microscope, and by operating them in field emission mode is also described. The field emission tips produced are intended to be used as an electron beam source for ion production via electron impact ionization of background gas or vapor in Penning trap mass spectrometry applications.

A method for electrochemically etching field emission tips is presented. Etching parameters are characterized and the operation of the tips in field emission mode is investigated.

A new variation of the drop-off method for fabricating field emission points by electrochemically etching tungsten rods in a NaOH solution is described. ...

A System to Create Stable Nanoparticle Aerosols from Nanopowders

Nanoparticle aerosols released from nanopowders in workplaces are associated with human exposure and health risks. We developed a novel system, requiring minimal amounts of test materials (min. 200 mg), for studying powder aerosolization behavior and aerosol properties. The aerosolization procedure follows the concept of the fluidized-bed process, but occurs in the modified volume of a V-shaped aerosol generator. The airborne particle number concentration is adjustable by controlling the air flow rate. The system supplied stable aerosol generation rates and particle size distributions over long periods (0.5-2 hr and possibly longer), which are important, for example, to study aerosol behavior, but also for toxicological studies. Strict adherence to the operating procedures during the aerosolization experiments ensures the generation of reproducible test results. The critical steps in the standard protocol are the preparation of the material and setup, and the aerosolization operations themselves. The system can be used for experiments requiring stable aerosol concentrations and may also be an alternative method for testing dustiness. The controlled aerosolization made possible with this setup occurs using energy inputs (may be characterized by aerosolization air velocity) that are within the ranges commonly found in occupational environments where nanomaterial powders are handled. This setup and its operating protocol are thus helpful for human exposure and risk assessment.

We designed and developed an effective nanopowder aerosolization setup and operating protocol. The system generated nanoparticle aerosols with stable number concentrations and size distributions for long durations, requiring only small quantities of test material (min. 200 mg).

Nanoparticle aerosols released from nanopowders in workplaces are associated with human exposure and health risks. We developed a novel system, requiring ...

Fabrication of Ultra-thin Color Films with Highly Absorbing Media Using Oblique Angle Deposition

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present an advanced method for fabricating ultra-thin color films with improved characteristics. The proposed process addresses several fabrication issues, including large area processing. Specifically, the protocol describes a process for fabricating ultra-thin color films using an electron beam evaporator for oblique angle deposition of germanium (Ge) and gold (Au) on silicon (Si) substrates.&#160; Film porosity produced by the oblique angle deposition induces color changes in the ultra-thin film. The degree of color change depends on factors such as deposition angle and film thickness. Fabricated samples of the ultra-thin color films showed improved color tunability and color purity. In addition, the measured reflectance of the fabricated samples was converted into chromatic values and analyzed in terms of color. Our ultra-thin film fabricating method is expected to be used for various ultra-thin film applications such as flexible color electrodes, thin film solar cells, and optical filters. Also, the process developed here for analyzing the color of the fabricated samples is broadly useful for studying various color structures.

We present a detailed method for fabricating ultra-thin color films with improved characteristics for optical coatings. The oblique angle deposition technique using an electron beam evaporator allows improved color tunability and purity. Fabricated films of Ge and Au on Si substrates were analyzed by reflectance measurements and color information conversion.

Ultra-thin film structures have been studied extensively for use as optical coatings, but performance and fabrication challenges remain.&#160; We present ...

Production and Characterization of Vacuum Deposited Organic Light Emitting Diodes

A method for producing simple and efficient thermally-activated delayed fluorescence organic light-emitting diodes (OLEDs) based on guest-host or exciplex donor-acceptor emitters is presented. With a step-by-step procedure, readers will be able to repeat and produce OLED devices based on simple organic emitters. A patterning procedure allowing the creation of personalized indium tin oxide (ITO) shape is shown. This is followed by the evaporation of all layers, encapsulation and characterization of each individual device. The end goal is to present a procedure that will give the opportunity to repeat the information presented in cited publication but also using different compounds and structures in order to prepare efficient OLEDs.

A protocol for the production of simple structured organic light-emitting diodes (OLEDs) is presented.

A method for producing simple and efficient thermally-activated delayed fluorescence organic light-emitting diodes (OLEDs) based on guest-host or exciplex ...