Polymer Photovoltaic Cells: Prototype Presentation April 15, 2010 JESUS GUARDADO, LEAH NATION, HUY NGUYEN, TINA RO

Understanding the Market of Solar Energy

Our Focus: Polymer Photovoltaic Cells Easily Fabricated Room T processing Printable More applications Light weight Flexible Current disadvantages Less stable Lower efficiency

Our Design & Objective: sw-CNTs SWCNT at 80,000x Objective: Improve the efficiency of PVC to increase competitiveness and allow for niche application use Carbon Nanotubes High e- affinity Improve carrier transport Improves performance Cost: $8 per m 2

How It Works: Layers are spin-coated Cell: Active layer Charge acceptors Electrodes

How It Works: Photons => Exitons Carbon Nanotubes: Charge transport Prevents recombination

How It Works: Electron => TiO 2 Hole => PEDOT

How It Works: Electrodes accept charges

Procedure Description Assembly Prepare solutions and centrifuge Spin coat substrate samples Electrode deposition Testing Efficiency calculation via I-V curve Optical absorption range of PPCs via UV Vis spectroscopy Characterization Nanostructure via AFM, TEM, SEM

Samples Blends: –Control (0% CNT) –Sample 1 (6% CNT) – Sample 2 (3.75% CNT) Layers (show picture): –FTO –PEDOT –P3HT/CNTs –TiO2 –Ag FTO - Fluoride Tin Oxide PEDOT - Poly(3,4-ethylenedioxythiophene) P3HT - poly(3-hexylthiophene)

Our Design: The Cell

Modifications Before: Spin coat at 2000 rpm 1 mg P3HT/mL chloroform Probe testing in dark box cm 2 area devices 10 device/slide After: Spin coat at 1000 rpm 4 mg P3HT/mL dichlorobenzene Probe testing in air 0.4cm 2 area devices 4 devices/ slide

Considerations behind our Modifications FTO instead of ITO  substrate availability 4 devices per glass slide  need precise tape placement P3HT solvent -> dichlorobenzene:  lower volatility

UV-Vis Results: Round II

Testing Results: Round II Sample 4 Concentration 1 Sample 6 Concentration 2

Next Steps 40 mg P3HT/mL dichlorobenzene ITO patterned slides o Pattern  no tape o ITO better light absorption range Spin coat P3HT layer 2x o Thicker  Less likely to short-circuit  Won't trap electrons and holes Spin coat solvent layer before P3HT/sw-CNT layer o Increase solubility

Current Progress & Future Schedule

Thank you. Questions? You may reach us at

Appendix

Renewable Energy Comparison

Cost Estimation $/grammg/mLL/slideslides/meter$/meter PRODUCTION COSTS, to be added to other company's approximation of $/meter CNT $15-20% cnts

Team's Resources Expertise: Helen Zeng; MIT Research Laboratory of Electronics Research Scientist Yin-lin Xie; MIT Materials Science and Engineering Technical Instructor Jill Rowehl; MIT Materials Science and Engineering Doctoral Candidate Laboratories: Institute of Soldier Nanotechnologies (ISN) Organic Nanostructure Electronics (ONE) Lab