Abstract

1. CuCl2 0.147 M PVP 15 mL EG 0.094 M AgNO3 Ag Nanowires Oil bath 150 °C 60 min 150 °C 15 min 150 °C 70 min Results Abstract Research Goal Increased demand for energy, coupled with high energy costs and environmental factors, makes solar energy a viable alternative to fossil fuels. Silicon solar panels account for 90% of the PV market which converts solar energy to electricity; but is neither cost- nor energy- efficient, especially pertaining to the Ag contact metal. A proposed solution phase scale-up production of Ag in the form of nanowires was successfully achieved to increase the efficiency of Ag for solar panels and printed electronics. To synthesize Ag nanowires by solution phase scale-up production that is applicable towards use in printed electronics. (a) 1x (b) 2x (c) 3x Synthesis Introduction • TEM Images of Ag Nanowires • Scale-up production to1x, 2x, and 3x • Particle impurities • The diameters of the resulting nanowires were ranging from 30 nm to 70 nm • The lengths of the resulting nanowires were ranging from 0.5 to 5 um. • Silicon (Si) Solar Panel • A photovoltaic (PV) cell consisting of Si crystalline structures which converts solar energy into electricity • Ag used in conductive electronics as electrical contact to pick up and transport electrons • Current Disadvantages • “Metallization” is a major efficiency-limiting and cost-determining step in solar cell processing. • Poor contact quality, wide spacing, and large width of powdered Ag ink gridlines • Ethylene glycol (EG) used as both solvent and reducing agent • Inert Argon gas applied to maximize product purity • Poly(vinylpyrrolidone)(PVP) used as surfactant (stabilizer) • Cu additive (CuCl2) used to reduce the amount of free Ag cations during initial seeding and to remove oxygen from the surface of the formed seeds Conclusion & Future Work • Successful Solution Phase Synthesis • Separation of product from phase solution • Scale-up production to1x, 2x, and 3x • Obtained 1 mg Ag nanowires / mL solution • Next Steps • Investigate over 10x scale-up production in batch reactor • Lower labor cost and improve time efficiency by using continuous reactor Courtesy of Dr. X.W. Teng Procedure • Referencing Korte et al, Published Article • Modified for 3x scale-up production • Assembly of Apparatus and Preparation of Reagents • 100 mL round-bottom flask displaced in an oil bath • Dissolving of solid reagents in EG via sonification • Order and Time of Reagent Addition • Heat 15 mL EG to 150 °C under reflux for 1 hour; with inert Argon, stirred magnetically at 500 RPM • Hot injection of CuCl2 for 15 minutes • Hot injection of 4.5 mL 0.147 M PVP followed by 4.5 mL 0.094 M AgNO3 for 90 minutes • Allow gradual cooling to room temperature • Separation Process • 1st : Acetone; 2nd , 3rd, 4th : Water via centrifugation • Store in water at room temperature • Typical Reaction Solution Color Changes • Clear to yellow (within 1 minute) • Red-orange (within 3 minutes) • Green with cloudiness (within 5 minutes) • Gradual shift to brown-red (within 30 minutes) • Opaque gray, wispiness texture (within 60 minutes) Proposed Solution Acknowledgements • Ag Nanowire Structure • Lower contact-resistance • Higher conductivity by one-dimensional infinitely long structures that increase electron current flow • Narrower Ag ink gridline width reduces shading effect • Cost and Labor Efficiency • Nanostructures maintain the same conductivity, but with less material than larger structures • Scale-up production gives more yield of Ag over time • Solution Phase Reaction • Simple and rapid synthesis of Ag nanowires • Controlled addition of reagents via pipettes; preventing quick supersaturation of Ag seeds in the reaction media leads to higher Ag yield • Research funded by NSF CMMI-1200544 • UNH Chemical Engineering Department • Faculty Advisor Professor Xiawei Teng and Dale Barkey • Graduate Student Wenxin Du • Collaborators • Don Banfield, Conductive Compounds, Inc. • Dr. Dong Su, Brookhaven National Laboratory, TEM measurement • Nancy Cherim, University of New Hampshire Instrumentation Center, TEM and EDS Solution Phase Synthesis of Silver Nanowires for Printed ElectronicsEmily Wong,Stephen M. West, Wenxin Du,Dale P. Barkey,Xiaowei Teng*Department of Chemical Engineering, University of New Hampshire Reference • Kylee Korte; Sara Skrabalak; and Younan Xia. J. Mater. Chem. 2008, 18, 437-441