Update 3April 29, 2010

JESUS GUARDADO, LEAH NATION, HUY NGUYEN, TINA RO

Agenda

• Project Background  • What's New

 • Results

 • Problems & Analysis• Changes

 • Future Plans

Flexible Cell

http://www.worldofrenewables.com

Project Background

 Polymeric Photovoltaic Cellso Low fabrication costso Fast processing speed o Light weighto Flexible

 Single Walled Carbon Nanotubes

o Aid transfer of electronso Improve Voc, Jsco $8 per m2

swCNTs at 80,000x

SWeNT SG 65, from CoMoCAT

Cell Design

FTO - Fluoride Tin OxidePEDOT - Poly(3,4-ethylenedioxythiophene)P3HT - poly(3-hexylthiophene)

Fabrication & Testing

Created samples:o 3 solutions => 6 sampleso 0, 3.75, 6 wt% CNTo Spin-coated onto substrateso Deposited electrodeo 1 sample => 4 devices

 Testing

o O.N.E. Lab's equipmento I-V curveso Voltmeter

Open circuit potential No light vs desk lamp

Samples

Devices with testing probes

Sample 1 (0% CNT)Location Without Light (mV) With Light (mV)

1 -- --2 -- --3 -- --

4 165 312

Sample 4 (6% CNT)Location Without Light (mV) With Light (mV)

1 125 2752 -- --

3 133 3104 82 198

Results: Photoresponse

Results: IV Curves

• Resistor-likeo resistor = centered at 0V

• Not diodeo no p-n junctiono electrons + holes go both ways

• Some samples had no response

IV Curve of Sample 1 - Location 4

Variables

Troubleshooting

Variables & Round 3

Modifications for Round 3

Changes• Smaller fabrication-testing window• Use 1% wt and 2% wt CNTs•  Increase P3HT:DCB to 10mg/mL

 Why?• Same as previous studies

o Geng & Zeng (2006)o Liu et al. (2008)

www.mse.edu

Current Progress & Future Schedule

Thank you. Questions?

You may reach us at nanosol@mit.eduhttp://web.mit.edu/course/3/3.042/team1_10

Results: I-V Curves

Sample Result                    Desired Diode Curve

Mg P3HT/mL solvent 1:1 4:1 40:1 Thicker P3HT layer

Solvent chloroform DCB DCB Less volatile

Spin coat rpm of P3HT/CNT layer

2000 1000 Lower rpm -> thicker layer

Spin coats of P3HT/CNT1x 2x WHY?

CNT wt% range INSERT 3.75, 6

Top electrode Ag Ag Ag Air stable, unlike Ca/Ag, LiF/Al

Bottom electrode ITO FTO FTO/ITO Availability