Name: an electrochemical cholesteric liquid crystalline device for quick and low-voltage color modulation
Uploaded: 2019-02-27T14:30:00
Description: Watch this Scientific Journal Video about An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation at JoVE.com

We&#160;thank Dr. Keisuke Tajima from RIKEN Center for Emergent Matter Science for valuable discussions. A part of this work was conducted at the Advanced Characterization Nanotechnology Platform of the University of Tokyo, supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. This work was financially supported by a JSPS Grant-in-Aid for Scientific Research (S) (18H05260) on &#34;Innovative Functional Materials based on Multi-Scale Interfacial Molecular Science&#34; for T.A. Y.I. is grateful for a JSPS Grant-in-Aid for Challenging Exploratory Research (16K14062). S.T. thanks the JSPS Young Scientist Fellowship.

1. Preparation of the cholesteric LC mixture
<ol>
	<li>Add 84.6 mg of 5OCB and 5.922 mg of FcD19&#160;(3.1 mol% to 5OCB) into a clean 10 mL glass vial.</li>
	<li>Add 12.9&#160;mg of EMIm-OTf and 10 mL of dichloromethane (CH2Cl2) into a new clean 10 mL glass vial and mix well. Transfer 2.1&#160;mL of the EMIm-OTf solution into the 5OCB- and FcD-containing glass vial. Gently shake the vial to let all th...

<ol>
	<li>Chandrasekhar, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Liquid Crystals. , (1992).</li><li>Blinov, L. M., Chigrinov, V. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Electrooptic Effects in Liquid Crystal Materials. , (1994).</li><li>Pieraccini, S., Masiero, S., Ferrarini, A., Spada, G. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chirality+transfer+across+length-scales+in+nematic+liquid+crystals:+fundamentals+and+applications.">Chirality transfer across length-scales in nematic liquid crystals: fundamentals and applications.</a> Chemical Society Reviews. 40 (1), 258-271 (2011).</li><li>Eelkama, R., Feringa, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Amplification+of+chirality+in+liquid+crystals.">Amplification of chirality in liquid crystals.</a> Organic &amp; Biomolecular Chemistry. 4 (20), 3729-3745 (2006).</li><li>Wang, L., Li, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stimuli-Directing+self-organized+3D+liquid-crystalline+nanostructures:+from+materials+design+to+photonic+applications.">Stimuli-Directing self-organized 3D liquid-crystalline nanostructures: from materials design to photonic applications.</a> Advanced Functional Materials. 26 (1), 10-28 (2016).</li><li>Bisoyi, H. K., Li, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-directing+chiral+liquid+crystal+nanostructures:+from+1D+to+3D.">Light-directing chiral liquid crystal nanostructures: from 1D to 3D.</a> Accounts of Chemical Research. 47 (10), 3184-3195 (2014).</li><li>van Delden, R. A., Koumura, N., Harada, N., Feringa, B. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Unidirectional+rotary+motion+in+a+liquid+crystalline+environment:+color+tuning+by+a+molecular+motor.">Unidirectional rotary motion in a liquid crystalline environment: color tuning by a molecular motor.</a> Proceedings of the National Academy of Sciences of the United States of America. 99 (8), 4945-4949 (2002).</li><li>Mathews, M., Tamaoki, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Planar+chiral+azobenzenophanes+as+chiroptic+switches+for+photon+mode+reversible+reflection+color+control+in+induced+chiral+nematic+liquid+crystals.">Planar chiral azobenzenophanes as chiroptic switches for photon mode reversible reflection color control in induced chiral nematic liquid crystals.</a> Journal of the American Chemical Society. 130 (34), 11409-11416 (2008).</li><li>Huang, Y., Zhou, Y., Doyle, C., Wu, S. -. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tuning+the+photonic+band+gap+in+cholesteric+liquid+crystals+by+temperature-dependent+dopant+solubility.">Tuning the photonic band gap in cholesteric liquid crystals by temperature-dependent dopant solubility.</a> Optics Express. 14 (3), 1236-1242 (2006).</li><li>Hu, W., 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=Magnetite+nanoparticles/chiral+nematic+liquid+crystal+composites+with+magnetically+addressable+and+magnetically+erasable+characteristics.">Magnetite nanoparticles/chiral nematic liquid crystal composites with magnetically addressable and magnetically erasable characteristics.</a> Liquid Crystals. 37 (5), 563-569 (2010).</li><li>Han, Y., Pacheco, K., Bastiaansen, C. W. M., Broer, D. J., Sijbesma, R. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Optical+monitoring+of+gases+with+cholesteric+liquid+crystals.">Optical monitoring of gases with cholesteric liquid crystals.</a> Journal of the American Chemical Society. 132 (9), 2961-2967 (2010).</li><li>Kelly, J. A., 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=Responsive+photonic+hydrogels+based+on+nanocrystalline+cellulose.">Responsive photonic hydrogels based on nanocrystalline cellulose.</a> Angewandte Chemie International Edition. 52 (34), 8912-8916 (2013).</li><li>Coles, H., Morris, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Liquid-crystal+lasers.">Liquid-crystal lasers.</a> Nature Photonics. 4 (10), 676-685 (2010).</li><li>Xiang, J., 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=Electrically+tunable+laser+based+on+oblique+heliconical+cholesteric+liquid+crystal.">Electrically tunable laser based on oblique heliconical cholesteric liquid crystal.</a> Proceedings of the National Academy of Sciences of the United States of America. 113 (46), 12925-12928 (2016).</li><li>Song, M. H., 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=Effect+of+phase+retardation+on+defect-mode+lasing+in+polymeric+cholesteric+liquid+crystals.">Effect of phase retardation on defect-mode lasing in polymeric cholesteric liquid crystals.</a> Advanced Materials. 16 (9-10), 779-783 (2004).</li><li>White, T. J., McConney, M. E., Bunning, T. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dynamic+color+in+stimuli-responsive+cholesteric+liquid+crystals.">Dynamic color in stimuli-responsive cholesteric liquid crystals.</a> Journal of Materials Chemistry. 20 (44), 9832-9847 (2010).</li><li>Bisoyi, H. K., Bunning, T. J., Li, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stimuli-driven+control+of+the+helical+axis+of+self-organized+soft+helical+superstructures.">Stimuli-driven control of the helical axis of self-organized soft helical superstructures.</a> Advanced Materials. 30 (25), 1706512 (2018).</li><li>Bisoyi, H. K., Li, Q. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Light-driven+liquid+crystalline+materials:+from+photo-induced+phase+transitions+and+property+modulations+to+applications.">Light-driven liquid crystalline materials: from photo-induced phase transitions and property modulations to applications.</a> Chemical Reviews. 116 (26), 15089-15166 (2016).</li><li>Tokunaga, S., Itoh, Y., Tanaka, H., Araoka, F., Aida, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Redox-responsive+chiral+dopant+for+quick+electrochemical+color+modulation+of+cholesteric+liquid+crystal.">Redox-responsive chiral dopant for quick electrochemical color modulation of cholesteric liquid crystal.</a> Journal of the American Chemical Society. 140 (35), 10946-10949 (2018).</li><li>Step&#780;nick&#780;a, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Ferrocenes: Ligands, Materials and Biomolecules. , (2008).</li><li>Togni, A., Hayashi, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Ferrocenes: Homogeneous Catalysis, Organic Synthesis, Materials Science. , (1995).</li><li>Fukino, T., Yamagishi, H., Aida, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Redox-responsive+molecular+systems+and+materials.">Redox-responsive molecular systems and materials.</a> Advanced Materials. 29 (25), 1603888 (2017).</li><li>Goh, M., Akagi, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Powerful+helicity+inducers:+axially+chiral+binaphthyl+derivatives.">Powerful helicity inducers: axially chiral binaphthyl derivatives.</a> Liquid Crystals. 35 (8), 953-965 (2008).</li><li>Xianyu, H., Faris, S., Crawford, G. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In-plane+switching+of+cholesteric+liquid+crystals+for+visible+and+near-infrared+applications.">In-plane switching of cholesteric liquid crystals for visible and near-infrared applications.</a> Applied Optics. 43 (26), 5006-5015 (2004).</li><li>Lin, T. H., 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=Electrically+controllable+laser+based+on+cholesteric+liquid+crystal+with+negative+dielectric+anisotropy.">Electrically controllable laser based on cholesteric liquid crystal with negative dielectric anisotropy.</a> Applied Physics Letters. 88 (6), 061122 (2006).</li><li>Bailey, C. A., 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=Surface+limitations+to+the+electro-mechanical+tuning+range+of+negative+dielectric+anisotropy+cholesteric+liquid+crystals.">Surface limitations to the electro-mechanical tuning range of negative dielectric anisotropy cholesteric liquid crystals.</a> Journal of Applied Physics. 111 (6), 063111 (2012).</li><li>Bailey, C. A., 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=Electromechanical+tuning+of+cholesteric+liquid+crystals.">Electromechanical tuning of cholesteric liquid crystals.</a> Journal of Applied Physics. 107 (1), 013105 (2010).</li><li>Xiang, J., 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=Electrically+tunable+selective+reflection+of+light+from+ultraviolet+to+visible+and+infrared+by+heliconical+cholesterics.">Electrically tunable selective reflection of light from ultraviolet to visible and infrared by heliconical cholesterics.</a> Advanced Materials. 27 (19), 3014-3018 (2015).</li><li>Hu, W., 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=Electrically+controllable+selective+reflection+of+chiral+nematic+liquid+crystal/chiral+ionic+liquid+composites.">Electrically controllable selective reflection of chiral nematic liquid crystal/chiral ionic liquid composites.</a> Advanced Materials. 22 (4), 468-472 (2010).</li><li>Choi, S. S., Morris, S. M. M., Huck, W. T. S., Coles, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electrically+tuneable+liquid+crystal+photonic+bandgaps.">Electrically tuneable liquid crystal photonic bandgaps.</a> Advanced Materials. 21 (38-39), 3915-3918 (2009).</li><li>Tokunaga, S., 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=Electrophoretic+deposition+for+cholesteric+liquid-crystalline+devices+with+memory+and+modulation+of+reflection+colors.">Electrophoretic deposition for cholesteric liquid-crystalline devices with memory and modulation of reflection colors.</a> Advanced Materials. 28 (21), 4077-4083 (2016).</li><li>Sen, M. S., Brahma, P., Roy, S. K., Mukherjee, D. K., Roy, S. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Birefringence+and+order+parameter+of+some+alkyl+and+alkoxycyanobiphenyl+liquid+crystals.">Birefringence and order parameter of some alkyl and alkoxycyanobiphenyl liquid crystals.</a> Molecular Crystrals and Liquid Crystals. 100 (3-4), 327-340 (1983).</li><li>McConney, M. E., 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=Electrically+induced+color+changes+in+polymer-stabilized+cholesteric+liquid+crystals.">Electrically induced color changes in polymer-stabilized cholesteric liquid crystals.</a> Advanced Optical Materials. 1 (6), 417-421 (2013).</li><li>Choi, S. S., Morris, S. M., Huck, W. T. S., Coles, H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+switching+properties+of+chiral+nematic+liquid+crystals+using+electrically+commanded+surfaces.">The switching properties of chiral nematic liquid crystals using electrically commanded surfaces.</a> Soft Matter. 5 (2), 354-362 (2009).</li><li>Sapp, S., Luebben, S., Losovyj, Y. B., Jeppson, P., Schulz, D. L., Caruso, A. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Work+function+and+implications+of+doped+poly(3,4-ethylenedioxythiophene)-co-poly(ethylene+glycol).">Work function and implications of doped poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol).</a> Applied Physics Letters. 88 (15), 152107 (2006).</li><li>Groenendaal, L., Jonas, F., Freitag, D., Pielartzik, H., Reynolds, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Poly(3,4-ethylenedioxythiophene)+and+its+derivatives:+past,+present,+and+future.">Poly(3,4-ethylenedioxythiophene) and its derivatives: past, present, and future.</a> Advanced Materials. 12 (7), 481-494 (2000).</li><li>Kirchmeyer, S., Reuter, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scientific+importance,+properties+and+growing+applications+of+poly(3,4-ethylenedioxythiophene).">Scientific importance, properties and growing applications of poly(3,4-ethylenedioxythiophene).</a> Journal of Materials Chemistry. 15 (21), 2077-2088 (2005).</li></ol>

Upon application of +1.5 V to the top ITO electrode (Figure 1C), FcD undergoes an oxidation reaction to generate FcD+. As the helical twisting power of FcD+ (101 &#181;m-1, Figure 1B) is lower than that ...

Cholesteric liquid crystals (LCs) are known to exhibit bright reflection colors due to their internal helical molecular arrangements1,2,3,4. The reflection wavelength &#955; is determined by the helical pitch P and the average refractive index n of the LC (&#955; = nP). Such LCs can be generated by doping chiral compounds (chiral dopants) to nematic LCs and its helical pitch is defined by the equation P = 1/&#946;MC, where &#946;M is the helical twisting power (HTP) and C is the molar fraction of the chiral dopant. Based on this notion, various chiral dopants that can respond to a variety of stimuli such as light5,6,7,8, heat9, magnetic field10, and gas11&#160;has been developed. Such properties are potentially useful for various applications such as sensors12&#160;and lasers13,14,15&#160;among others16,17,18.
Recently, we developed the first redox-responsive chiral dopant FcD (Figure 1A)19&#160;that can change its HTP value in response to redox reactions. FcD is composed of a ferrocene unit, which can undergo reversible redox reactions20,21,22, and a binaphthyl unit, which is known to exhibit high HTP value23. The cholesteric LC doped with FcD, in the presence of a supporting electrolyte, can change its reflection color within 0.4 s and recover its original color in 2.7 s upon voltage application of +1.5 and 0 V, respectively. The high response speed and low operating voltage observed for the device is unprecedented among any other cholesteric LC device so far reported.
One of the important applications of the cholesteric LCs is in reflective displays, whose energy consumption rate is much lower than the conventional LC displays. For this purpose, cholesteric LCs should change its reflection color with electrical stimuli. However, most of the previous methodologies utilize an electrical coupling between the applied electrical stimuli and the host LC molecules, which requires high voltage over 40 V24,25,26,27,28. For the use of the electrically responsive chiral dopant, there are only few examples29,30&#160;including our previous work31, which also requires high voltage with low response speed. Considering these previous works, the performance of our FcD-doped cholesteric LC device, especially for the fast color modulation speed (0.4 s) and low operating voltage (1.5 V), is a groundbreaking achievement that can greatly contribute to the development of next generation reflective displays. In this detailed protocol, we demonstrate the fabrication processes and the operating procedures of the prototype cholesteric LC display devices.

<table border="0" cellpadding="0" cellspacing="0" style="width:1295px;" width="1295">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate, 98%</td>
			<td style="width:211px;">TCI</td>
			<td style="width:163px;">E0494</td>
			<td style="width:343px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">4-Cyano-4&#39;-pentyloxybiphenyl, 98%</td>
			<td style="width:211px;">TCI</td>
			<td style="width:163px;">C1551</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Diamond tipped glass cutter</td>
			<td style="width:211px;">AS ONE</td>
			<td style="width:163px;">6-539-05</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Dichloromethane, 99.5%</td>
			<td style="width:211px;">KANTO CHEMICAL</td>
			<td style="width:163px;">10158-2B</td>
			<td>HPLC grade</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Differential Scanning Calorimeter</td>
			<td style="width:211px;">METTLER TOLEDO</td>
			<td style="width:163px;">DSC 1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Digital microscope&#160;</td>
			<td style="width:211px;">KEYENCE</td>
			<td style="width:163px;">VHX-5000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Extran MA01</td>
			<td style="width:211px;">Merck</td>
			<td style="width:163px;">107555</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Fully ITO-coated glass plate</td>
			<td style="width:211px;"></td>
			<td style="width:163px;"></td>
			<td>Costum order, Resistance: ~30&#937;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Glass beads</td>
			<td style="width:211px;">Thermo Fisher Scientific</td>
			<td style="width:163px;">9005</td>
			<td>5 &#177; 0.3 &#956;m in diameter</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Hot stage</td>
			<td style="width:211px;">INSTEC</td>
			<td style="width:163px;">mK1000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">ITO-patterned glass plate</td>
			<td style="width:211px;"></td>
			<td style="width:163px;"></td>
			<td>Costum order, Resistance: ~30&#937;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Oil rotary vacuum pump</td>
			<td style="width:211px;">SATO VAC</td>
			<td style="width:163px;">TSW-150</td>
			<td>Pressure: ~5 Pa</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Optical adhesive</td>
			<td style="width:211px;">Noland</td>
			<td style="width:163px;">NOA81</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Poly(3,4-ethylenedioxythiophene), bis-poly(ethyleneglycol), lauryl terminated</td>
			<td style="width:211px;">Sigma Aldrich</td>
			<td style="width:163px;">687316</td>
			<td>0.7 wt% (dispersion in nitromethane)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Potentiostat</td>
			<td style="width:211px;">TOHO TECHNICAL RESEARCH</td>
			<td style="width:163px;">PS-08</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Rubbing machine</td>
			<td style="width:211px;">EHC</td>
			<td style="width:163px;">MRJ-100S</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Spectrophotometer</td>
			<td style="width:211px;">JASCO</td>
			<td style="width:163px;">V-670 UV/VIS/NIR</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Spin coater</td>
			<td style="width:211px;">MIKASA</td>
			<td style="width:163px;">1H-D7</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Ultrapure water</td>
			<td style="width:211px;">Merck&#160;</td>
			<td style="width:163px;">Milli-Q Integral 3</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">Ultrasonic bath</td>
			<td style="width:211px;">AS ONE</td>
			<td style="width:163px;">ASU-2</td>
			<td>Power: 40 W</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ultrasonic soldering</td>
			<td style="width:211px;">KURODA TECHNO</td>
			<td style="width:163px;">SUNBONDER USM-IV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:579px;">UV lamp</td>
			<td style="width:211px;">AS ONE</td>
			<td style="width:163px;">SLUV-4</td>
			<td>Power: 4 W</td>
		</tr>
	</tbody>
</table>

an electrochemical cholesteric liquid crystalline device for quick and low-voltage color modulation

We demonstrate a method for fabricating a prototype reflective display device that contains cholesteric liquid crystal (LC) as an active component. The cholesteric LC is composed of a nematic LC 4&#39;-pentyloxy-4-cyanobiphenyl (5OCB), redox-responsive chiral dopant (FcD), and a supporting electrolyte 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMIm-OTf). The most important component is FcD. This molecule changes its helical twisting power (HTP) value in response to redox reactions. Therefore, in situ electrochemical redox reactions in the LC mixture allow for the device to change its reflection color in response to electrical stimuli. The LC mixture was introduced, by a capillary action, into a sandwich-type ITO glass cell comprising two glass slides with patterned indium tin oxide (ITO) electrodes, one of which was coated with poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol) doped with perchlorate (PEDOT+). Upon application of +1.5 V, the reflection color of the device changed from blue (467 nm) to green (485 nm) in 0.4 s. Subsequent application of 0 V made the device recover the original blue color in 2.7 s. This device is characterized by its fastest electrical response and lowest operating voltage among any previously reported cholesteric LC device. This device could pave the way for the development of next generation reflective displays with low energy consumption rates.

Photographs, transmittance spectra, and time dependent transmittance change profiles at 510 nm are collected for the LC device containing FcD-doped (3.1 mol%) cholesteric LC in the presence of EMIm-OTf (3.0 mol%) during the voltage application cycles between 0 and +1.5 V at 37 &#176;C.
The LC mixture containing FcD (3.1 mo...

Watch this Scientific Journal Video about An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation at JoVE.com

An Electrochemical Cholesteric Liquid Crystalline Device for Quick and Low-Voltage Color Modulation

A protocol for the fabrication of a reflective cholesteric liquid crystalline display device containing a redox-responsive chiral dopant allowing quick and low-voltage operation is presented.

We demonstrate a method for fabricating a prototype reflective display device that contains cholesteric liquid crystal (LC) as an active component. The ...

Cholesteric liquid crystals are known to have bright reaction colors, and the fast color modulation is important for the development of next generation of reflective displays. Our method enables the fastest color modulation with the lowest operation voltage ever reported for cholesteric liquid crystals. The key is FcD.A chiral dopant with redox responsive helical twisting power. Demonstrating the procedure will be Shoichi Tokunaga, a postdoc, and Mengyan Zeng, a graduate student from our laboratory. To begin preparing the cholesteric liquid crystal mixture, place 84.6 milligrams of 5OCB and 5.922 milligrams of FcD in a 10 milliliter glass vial.In a separate vial, dissolve 12.9 milligrams of EMIm-OTf in 10 milliliters of dichloromethane. Transfer 2.1 milliliters of the EMIm-OTf solution to the liquid crystal mixture, and mix the components well by gently shaking the vial. Then, cover the vial with aluminum foil, and punch several holes in the foil with a needle.Heat the solution at 80 degrees celsius for one hour to evaporate most of the DCM. Put the vial under vacuum, and continue heating it for another hour to remove the remaining DCM to obtain a clear, orange liquid crystal mixture. Next, to begin preparing the ITO glass, cut a 10 by 10 millimeter piece of glass patterned with ITO in the desired shape, and a 10 by 12 millimeter piece of standard ITO glass.Place both pieces of ITO glass in the diluted surfactant without letting them touch. Combine 60 milliliters of an alkaline surfactant solution, and 240 milliliters of ultra pure water in a 500 milliliter glass container. Sonicate the plates in dilute alkaline surfactant for 30 minutes.Then, decant the surfactant, and rinse the plates with 200 milliliter portions of ultra pure water. Perform this rinsing procedure three times in total. Refill the container with 300 milliliters of ultra pure water.Sonicate the plates for 20 minutes. And decant the water. Wash the plates in ultra pure water in this way three times in total.Finally, dry the clean plates with a stream of nitrogen gas and store them in clean, disposable petri dishes. Keep the dishes in a clean desiccator. To begin preparing the cell, sonicate a 0.7 percent by weigh dispersion of PEDOT in nitromethane for 60 minutes to ensure that the polymer is well dispersed.Then, fix the clean standard ITO glass on a spin coater, and remove dust from the ITO coated surface with a nitrogen blow gun. Carefully apply 50 microliters of freshly sonicated PEDOT dispersion to the ITO surface and spin coat the plate at 1000 RPM for 60 seconds. Let the coated plate sit in ambient air for one hour afterwards.Next, fix the patterned ITO plate in a rubbing machine equipped with a rayon cloth. Thoroughly rub the ITO patterned surface under a stream of nitrogen gas. Then, in a dust-free area, mix a drop of optical adhesive with a similarly sized quantity of 5 micrometer borosilicate glass beads.Lay the PEDOT coated plate face up on the work space. Apply about 0.2 cubic millimeters of the adhesive mixture to each corner of one narrow side of the plate. Apply two more portions of adhesive eight millimeters away from that side to form an eight by 10 millimeter rectangle on the plate.Place the patterned ITO plate face down on the adhesive with one edge aligned with the drops partway along the PEDOT coated plate so that the plates are offset by about two millimeters. Gently press down the corners of the cell to achieve a uniform gap between the plates as indicated by the disappearance of the fringe pattern in the cell. Eradiate the cell with 365 nanometer UV light for 20 seconds to set the adhesive.Heat the cell on a hot plate at 100 degrees celsius for three hours to finish curing the adhesive. Lastly, connect conducting wires fitted with aligator clips to the exposed ITO surface on each plate by ultrasonic sautering. Use insulating tape to fix the wires of the glass cell to a microscope slide for easier handling later.Heat the ITO glass, a small spatula, and the cholesteric liquid crystal mixture at 80 degrees celsius for 10 to 15 minutes. Then, quickly transfer a small amount of the hot cholesteric liquid crystal mixture to the gap between the plates with the heated spatula. The cell will fill by capillary action in about 60 seconds.Once the cell is full, reduce the stage temperature to 37 degrees celsius and wait for the cell to stabilize at that temperature. Apply sheer force by gently pressing the center of the liquid crystal device to see the bright reflected color. Then, place the device on top of the hot stage under a digital optical microscope with the patterned side of the device facing the lens.Connect the patterned and PEDOT coated plates to the positive and negative terminals of a poteniostat respectively. Configure the poteniostat to alternate between applying 1.5 volts for four seconds, and 0 volts for eight seconds. Observe and record the color change of the liquid crystal device with the digital microscope while cycling the voltage.Next, set up a UV-vis spectrophotometer to scan transmittance from 800 to 300 nanometers. Put a small jack in the sample compartment to hold the hot stage. Place the liquid crystal device on a hot plate to keep warm and acquire a background measurement of the empty hot stage.Then, load the device back into the hot stage and place it in the spectrometer with the patterned side facing the beam. Use a dark cloth to cover gaps between the sample chamber door and the wires. Wait a few minutes for the device to stabilize at 37 degrees celsius.If necessary, adjust the position of the hot stage to maximize transmittance. Then, acquire an initial spectrum of transmittance through the device. After that, apply a 1.5 volts to the device for four seconds and immediately acquire a transmittance spectrum.When the measurement finishes, apply 0 volts to the device for eight seconds and acquire another spectrum. Finally, record percent transmittance at 510 nanometers over time while cycling the voltage between 1.5 volts for four seconds and 0 volts for eight seconds five times. The cholesteric liquid crystal doped with a chiral ferrocene binaphtol complex, appeared bright blue and had a reflection band centered at 467 nanometers.Applying 1.5 volts to an ITO electrode in contact with the liquid crystal solution, shifted the reflectance band to center on 485 nanometers. The oxidized cholesteric liquid crystal appeared bright cyan to green against the unoxidized blue surroundings. The reflectance band shifted back to 467 nanometers upon applying 0 volts to the electrode with a corresponding recovery of the blue reflection color.Transmittance decreased modestly with repeated cycles because of increasing orientational disorder, but this was repaired by applying a sheer force to the device. The color change from blue to cyan occurred in 0.4 seconds, and the return change took 2.7 seconds. Alternately applying 1.5 volts for 0.5 seconds, and 0 volts for five seconds resulted in a blinking electrode.When attempting the procedure, please take care when assembling the cell. The quality of the cell determines the quality of the display image of the device. You can identify the appropriate voltage range for operating the device using cyclic voltammetry.X-ray for the electron spectroscopy can confirm that emergence of the oxidized part in the liquid crystalline material. By precisely tuning the chemical structure of the redox responsive chirol dopant and other components, we can develop new types of reflective displays, such as full color e-paper. Further investigation of the mechanism of our chirol dopant, can deepen the fundamental science of cholesteric liquid crystals where the molecular mechanism of chirol induction is still unclear.

an-electrochemical-cholesteric-liquid-crystalline-device-for-quick

Research

JoVE Journal

Chemistry

Dynamic Electrochemical Measurement of Chloride Ions

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver chloride electrode is used extensively for potentiometric measurement of chloride ions concentration in electrolyte. In this measurement, long-term and continuous monitoring is limited due to the inherent drift and the requirement of a stable reference electrode. We utilized the chronopotentiometric approach to minimize drift and avoid the use of a conventional reference electrode. A galvanostatic pulse is applied to an Ag/AgCl electrode which initiates a faradic reaction depleting the Cl&#713; ions near the electrode surface. The transition time, which is the time to completely deplete the ions near the electrode surface, is a function of the ion concentration, given by the Nernst equation. The square root of the transition time is in linear relation to the chloride ion concentration. Drift of the response over two weeks is negligible (59 &#181;M/day) when measuring 1 mM [Cl&#713;]using a current pulse of 10 Am-2. This is a dynamic measurement where the moment of transition time determines the response and thus is independent of the absolute potential. Any metal wire can be used as a pseudo-reference electrode, making this approach feasible for long-term measurement inside concrete structures.

Dynamic measurement of chloride ions is presented. Transition time of an Ag/AgCl electrode, during a chronopotentiometric technique, can give the concentration of chloride ions in electrolyte. This method does not require a stable conventional reference electrode.

This protocol describes the dynamic measurement of chloride ions using the transition time of a silver silver chloride (Ag/AgCl) electrode. Silver silver ...

Synthesis of Programmable Main-chain Liquid-crystalline Elastomers Using a Two-stage Thiol-acrylate Reaction

This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline elastomers (LCEs) with facile control over network structure and programming of an aligned monodomain. Tailored LCE networks were synthesized using routine mixing of commercially available starting materials and pouring monomer solutions into molds to cure. An initial polydomain LCE network is formed via a self-limiting thiol-acrylate Michael-addition reaction. Strain-to-failure and glass transition behavior were investigated as a function of crosslinking monomer, pentaerythritol tetrakis(3-mercaptopropionate) (PETMP). An example non-stoichiometric system of 15 mol% PETMP thiol groups and an excess of 15 mol% acrylate groups was used to demonstrate the robust nature of the material. The LCE formed an aligned and transparent monodomain when stretched, with a maximum failure strain over 600%. Stretched LCE samples were able to demonstrate both stress-driven thermal actuation when held under a constant bias stress or the shape-memory effect when stretched and unloaded. A permanently programmed monodomain was achieved via a second-stage photopolymerization reaction of the excess acrylate groups when the sample was in the stretched state. LCE samples were photo-cured and programmed at 100%, 200%, 300%, and 400% strain, with all samples demonstrating over 90% shape fixity when unloaded. The magnitude of total stress-free actuation increased from 35% to 115% with increased programming strain. Overall, the two-stage TAMAP methodology is presented as a powerful tool to prepare main-chain LCE systems and explore structure-property-performance relationships in these fascinating stimuli-sensitive materials.

A novel methodology is presented to synthesize and program main-chain liquid-crystalline elastomers using commercially available starting monomers. A wide range of thermomechanical properties was tailored by adjusting the amount of crosslinker, while the actuation performance was dependent on the amount of applied strain during programming.

This study presents a novel two-stage thiol-acrylate Michael addition-photopolymerization (TAMAP) reaction to prepare main-chain liquid-crystalline ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Phthalic Acid Ester-Binding DNA Aptamer Selection, Characterization, and Application to an Electrochemical Aptasensor

Phthalic acid esters (PAEs) areone of the major groups of persistent organic pollutants. The group-specific detection of PAEs is highly desired due to the rapid growing of congeners. DNA aptamers have been increasingly applied as recognition elements on biosensor platforms, but selecting aptamers toward highly hydrophobic small molecule targets, such as PAEs, is rarely reported. This work describes a bead-based method designed to select group-specific DNA aptamers to PAEs. The amino group functionalized dibutyl phthalate (DBP-NH2) as the anchor target was synthesized and immobilized on the epoxy-activated agarose beads, allowing the display of the phthalic ester group at the surface of the immobilization matrix, and therefore the selection of the group-specific binders. We determined the dissociation constants of the aptamer candidates by quantitative polymerization chain reaction coupled with magnetic separation. The relative affinities and selectivity of the aptamers to other PAEs were determined by the competitive assays, where the aptamer candidates were pre-bounded to the DBP-NH2 attached magnetic beads and released to the supernatant upon incubation with the tested PAEs or other potential interfering substances. The competitive assay was applied because it provided a facile affinity comparison among PAEs that had no functional groups for surface immobilization. Finally, we demonstrated the fabrication of an electrochemical aptasensor and used it for ultrasensitive and selective detection of bis(2-ethylhexyl) phthalate. This protocol provides insights for the aptamer discovery of other hydrophobic small molecules.

A protocol for the in vitro selection and characterization of group-specific phthalic acid ester- binding DNA aptamers is presented. The application of the selected aptamer in an electrochemical aptasensor is also included.

Phthalic acid esters (PAEs) areone of the major groups of persistent organic pollutants. The group-specific detection of PAEs is highly desired due to the ...

Synthesis and Performance Characterizations of Transition Metal Single Atom Catalyst for Electrochemical CO2 Reduction

This protocol presents both the synthesis method of the Ni single atom catalyst, and the electrochemical testing of its catalytic activity and selectivity in aqueous CO2 reduction. Different from traditional metal nanocrystals, the synthesis of metal single atoms involves a matrix material that can confine those single atoms and prevent them from aggregation. We report an electrospinning and thermal annealing method to prepare Ni single atoms dispersed and coordinated in a graphene shell, as active centers for CO2 reduction to CO. During the synthesis, N dopants play a critical role in generating graphene vacancies to trap Ni atoms. Aberration-corrected scanning transmission electron microscopy and three-dimensional atom probe tomography were employed to identify the single Ni atomic sites in graphene vacancies. Detailed setup of electrochemical CO2 reduction apparatus coupled with an on-line gas chromatography is also demonstrated. Compared to metallic Ni, Ni single atom catalyst exhibit dramatically improved CO2 reduction and suppressed H2 evolution side reaction.

Synthesis and Performance Characterizations of Transition Metal Single Atom Catalyst for Electrochemical CO2 Reduction

Here, we present a protocol for the synthesis and electrochemical testing of transition metal single atoms coordinated in graphene vacancies as active centers for selective carbon dioxide reduction to carbon monoxide in aqueous solutions.

This protocol presents both the synthesis method of the Ni single atom catalyst, and the electrochemical testing of its catalytic activity and selectivity ...

Microfluidic Preparation of Liquid Crystalline Elastomer Actuators

This paper focuses on the microfluidic process (and its parameters) to prepare actuating particles from liquid crystalline elastomers. The preparation usually consists in the formation of droplets containing low molar mass liquid crystals at elevated temperatures. Subsequently, these particle precursors are oriented in the flow field of the capillary and solidified by a crosslinking polymerization, which produces the final actuating particles. The optimization of the process is necessary to obtain the actuating particles and the proper variation of the process parameters (temperature and flow rate) and allows variations of size and shape (from oblate to strongly prolate morphologies) as well as the magnitude of actuation. In addition, it is possible to vary the type of actuation from elongation to contraction depending on the director profile induced to the droplets during the flow in the capillary, which again depends on the microfluidic process and its parameters. Furthermore, particles of more complex shapes, like core-shell structures or Janus particles, can be prepared by adjusting the setup. By the variation of the chemical structure and the mode of crosslinking (solidification) of the liquid crystalline elastomer, it is also possible to prepare actuating particles triggered by heat or UV-vis irradiation.

This article describes the microfluidic process and parameters to prepare actuating particles from liquid crystalline elastomers. This process allows the preparation of actuating particles and the variation of their size and shape (from oblate to strongly prolate, core-shell, and Janus morphologies) as well as the magnitude of actuation.

This paper focuses on the microfluidic process (and its parameters) to prepare actuating particles from liquid crystalline elastomers. The preparation ...

Preparation of Graphene-Supported Microwell Liquid Cells for In Situ Transmission Electron Microscopy

The fabrication and preparation of graphene-supported microwell liquid cells (GSMLCs) for in situ electron microscopy is presented in a stepwise protocol. The versatility of the GSMLCs is demonstrated in the context of a study about etching and growth dynamics of gold nanostructures from a HAuCl4 precursor solution. GSMLCs combine the advantages of conventional silicon- and graphene-based liquid cells by offering reproducible well depths together with facile cell manufacturing and handling of the specimen under investigation. The GSMLCs are fabricated on a single silicon substrate which drastically reduces the complexity of the manufacturing process compared to two-wafer-based liquid cell designs. Here, no bonding or alignment process steps are required. Furthermore, the enclosed liquid volume can be tailored to the respective experimental requirements by simply adjusting the thickness of a silicon nitride layer. This enables a significant reduction of window bulging in the electron microscope vacuum. Finally, a state-of-the-art quantitative evaluation of single particle tracking and dendrite formation in liquid cell experiments using only open source software is presented.

Preparation of Graphene-Supported Microwell Liquid Cells for In Situ Transmission Electron Microscopy

A protocol for preparation of graphene-supported microwell liquid cells for in situ electron microscopy of gold nanocrystals from HAuCl4 precursor solution is presented. Furthermore, an analysis routine is presented to quantify observed etching and growth dynamics.

The fabrication and preparation of graphene-supported microwell liquid cells (GSMLCs) for in situ electron microscopy is presented in a stepwise protocol. ...

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal

Smart viscoelastic materials that respond to specific stimuli are one of the most attractive classes of materials important to future technologies, such as on-demand switchable adhesion technologies, actuators, molecular clutches, and nano-/microscopic mass transporters. Recently it was found that through a special solid-liquid transition, rheological properties can exhibit significant changes, thus providing suitable smart viscoelastic materials. However, designing materials with such a property is complex, and forward and backward switching times are usually long. Therefore, it is important to explore new working mechanisms to realize solid-liquid transitions, shorten the switching time, and enhance the contrast of rheological properties during switching. Here, a light-induced crystal-liquid phase transition is observed, which is characterized by means of polarizing light microscopy (POM), photorheometry, photo-differential scanning calorimetry (photo-DSC), and X-ray diffraction (XRD). The light-induced crystal-liquid phase transition presents key features such as (1) fast switching of crystal-liquid phases for both forward and backward reactions and (2) a high contrast ratio of viscoelasticity. In the characterization, POM is advantageous in offering information on the spatial distribution of LC molecule orientations, determining the type of liquid crystalline phases appearing in the material, and studying the orientation of LCs. Photorheometry allows measurement of a material&#8217;s rheological properties under light stimuli and can reveal the photorheological switching properties of materials. Photo-DSC is a technique to investigate thermodynamic information of materials in darkness and under light irradiation. Lastly, XRD allows studying of microscopic structures of materials. The goal of this article is to clearly present how to prepare and measure the discussed properties of a photorheological material.

This protocol demonstrates the preparation of a photorheological material that exhibits a solid phase, various liquid crystalline phases, and an isotropic liquid phase by increasing temperature. Presented here are methods for measuring the structure-viscoelasticity relationship of the material.

Smart viscoelastic materials that respond to specific stimuli are one of the most attractive classes of materials important to future technologies, such ...

Asymmetric Thermoelectrochemical Cell for Harvesting Low-grade Heat under Isothermal Operation

Low-grade heat is abundantly available in the environment as waste heat. The efficient conversion of low-grade heat into electricity is very difficult. We developed an asymmetric thermoelectrochemical cell (aTEC) for heat-to-electricity conversion under isothermal operation in the charging and discharging processes without exploiting the thermal gradient or the thermal cycle. The aTEC is composed of a graphene oxide (GO) cathode, a polyaniline (PANI) anode, and 1M KCl as the electrolyte. The cell generates a voltage due to the pseudocapacitive reaction of GO when heating from room temperature (RT) to a high temperature (TH, ~40-90 &#176;C), and then current is successively produced by oxidizing PANI when an external electrical load is connected. The aTEC demonstrates a remarkable temperature coefficient of 4.1 mV/K and a high heat-to-electricity conversion efficiency of 3.32%, working at a TH = 70 &#176;C with a Carnot efficiency of 25.3%, unveiling a new promising thermoelectrochemical technology for low-grade heat recovery.

Low-grade heat is abundant, but its efficient recovery is still a great challenge. We report an asymmetric thermoelectrochemical cell using graphene oxide as a cathode and polyaniline as an anode with KCl as the electrolyte. This cell works under isothermal heating, exhibiting a high heat-to-electricity conversion efficiency in low-temperature regions.

Low-grade heat is abundantly available in the environment as waste heat. The efficient conversion of low-grade heat into electricity is very difficult. We ...

ARL Spectral Fitting as an Application to Augment Spectral Data via Franck-Condon Lineshape Analysis and Color Analysis

The ARL Spectral Fitting application provides a free, publicly accessible, and fully transparent method for performing Franck-Condon Lineshape Analysis (FCLSA) on spectral data, in addition to CIE color coordinate determination and basic spectral processing. While some of the features may be found in commercial software or in programs made by&#160;academic research groups, we believe that ARL Spectral Fitting is the only application that possesses all three of the aforementioned attributes.
This program is intended as a standalone, GUI-based application for use by an average laboratory researcher without requiring any coding knowledge or proprietary software. In addition to the standalone executable hosted on ARL GitHub, the associated MATLAB files are available for use and further development.
FCLSA augments the information found in luminescence spectra, providing meaningful insight into the relationship between the ground and excited states of a photoluminescent species. This insight is achieved by modeling spectra with two versions (modes) of an equation that are characterized by either four or six parameters, depending on which mode is used. Once optimized, the value of each of these parameters can be used to gain insight into the molecule, as well as to perform further analysis (for example, the free energy content of the excited-state molecule). This application provides tools for easy by-hand fitting of imported data, as well as two methods for optimizing this fit-damped least-squares fitting, powered by the Levenberg-Marquardt algorithm, and derivative-free fitting utilizing the Nelder-Mead simplex algorithm. Furthermore, estimations of sample color can be performed and reported in CIE and RGB coordinates.

This protocol introduces Franck-Condon Lineshape Analyses (FCLSA) of emission spectra and serves as a tutorial for the use of ARL Spectral Fitting software. The open-source software provides an easy and intuitive way to perform advanced analysis of emission spectra including excited state energy calculations, CIE color coordinate determination, and FCLSA.

The ARL Spectral Fitting application provides a free, publicly accessible, and fully transparent method for performing Franck-Condon Lineshape Analysis ...