Abstract

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

Kylee Korte; Sara Skrabalak; and Younan Xia. J. Mater. Chem. 2008, 18, 437-441

Ag Nanowire StructureLower contact-resistanceHigher conductivity by one-dimensional infinitely long structures that increase electron current flowNarrower Ag ink gridline width reduces shading effect

Cost and Labor EfficiencyNanostructures maintain the same conductivity, but with less material than larger structuresScale-up production gives more yield of Ag over time

Solution Phase ReactionSimple and rapid synthesis of Ag nanowiresControlled addition of reagents via pipettes; preventing quick supersaturation of Ag seeds in the reaction media leads to higher Ag yield

Synthesis

Conclusion & Future Work

Acknowledgements

Reference

Results

Introduction

Proposed Solution

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

Successful Solution Phase SynthesisSeparation of product from phase solution Scale-up production to1x, 2x, and 3xObtained 1 mg Ag nanowires / mL solution

Next StepsInvestigate over 10x scale-up production in batch reactorLower labor cost and improve time efficiency by using continuous reactor

To synthesize Ag nanowires by solution phase scale-up production that is applicable towards use in printed electronics.

Research Goal

Procedure

Silicon (Si) Solar PanelA photovoltaic (PV) cell consisting of Si crystalline structures which converts solar energy into electricityAg 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

Oil bath

15 mL EG

CuCl20.147 M

PVP

150 °C60 min

150 °C15 min

150 °C70 min

0.094 M AgNO3

Ag Nanowires

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.

Courtesy of Dr. X.W. Teng

(a) 1x (b) 2x (c) 3x

TEM Images of Ag Nanowires

Scale-up production to1x, 2x, and 3xParticle impuritiesThe diameters of the resulting nanowires were ranging from 30 nm to 70 nmThe lengths of the resulting nanowires were ranging from 0.5 to 5 um.

Referencing Korte et al, Published ArticleModified for 3x scale-up productionAssembly of Apparatus and Preparation of Reagents100 mL round-bottom flask displaced in an oil bathDissolving of solid reagents in EG via sonification

Order and Time of Reagent AdditionHeat 15 mL EG to 150 °C under reflux for 1 hour; with inert Argon, stirred magnetically at 500 RPMHot injection of CuCl2 for 15 minutesHot injection of 4.5 mL 0.147 M PVP followed by 4.5 mL 0.094 M AgNO3 for 90 minutesAllow gradual cooling to room temperature

Separation Process1st : Acetone; 2nd , 3rd, 4th : Water via centrifugationStore in water at room temperature

Typical Reaction Solution Color ChangesClear 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)