thin film fabrication and morphology studies
TRANSCRIPT
![Page 1: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/1.jpg)
Thin Film Fabrication and Morphology Studies
Kate Dickinson
Mentor: Mike Brady
PI: Dr. Michael Chabinyc
![Page 2: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/2.jpg)
Introduction
• Organic photovoltaics (OPVs) aim to provide simple and efficient sources of clean energy
• OPVs have a maximum efficiency of ~5%
• Multiple methods of thin film fabrication
www.konarka.com
![Page 3: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/3.jpg)
Introduction
www.konarka.com
World Record: 8.3% Efficiency (Roll-to-Roll Printing Method)
![Page 4: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/4.jpg)
Introduction
ITO Substrate
PEDOT:PSS
P3HT:PCBM Active Layer
Aluminum Electrode
P3HT:PCBM Photovoltaic
Courtesy of A. Muñoz
Fabrica'on techniques determine morphology and cell efficiency
![Page 5: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/5.jpg)
ITO Electrode
Aluminum Electrode
1) Light Absorption
2) Exciton Diffusion
3) Charge Separation
4) Charge Transport
5) Clean Energy
Introduction OPVs use a electron-hole (exciton) system to transport charge
Courtesy of A. Ostrowski and B. Walker
![Page 6: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/6.jpg)
Materials • P3HT: Electron Donor
Poly(3-hexylthiophene) p-type semiconductor
• PCBM: Electron Acceptor [6,6]-phenyl C61 butyric acid methyl ester n-type semiconductor
![Page 7: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/7.jpg)
General Research Focus
• How can OPV technology be improved?
• How can fabrication techniques be improved without losing efficiency?
www.konarka.com
![Page 8: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/8.jpg)
• Parameter Relationships: How are blade coating parameters related?
• Film Morphology: How does morphology change for different blade coating parameters?
• Crystallinity: How can P3HT:PCBM crystallinity be controlled and enhance charge mobility?
RET I Focus
![Page 9: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/9.jpg)
Spin Coating: Spreads film across substrate while controlling rpm and time
Thin Film Fabrication Methods
Deposition Drying Film
Substrate
Spin
Courtesy of A. Muñoz
![Page 10: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/10.jpg)
Blade Coating: Spreads film across substrate while controlling temperature, speed and blade height
Thin Film Fabrication Methods
Blade
Heat Plate, T(°C)
BASE
Substrate Solution
θ Velocity
Heat Plate, T(°C)
BASE
V
Heat Plate, T(°C)
BASE
Film
Courtesy of A. Muñoz
![Page 11: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/11.jpg)
Thin Film Fabrication Methods
P3HT:PCBM Photovoltaics
Spin Coated OPV Blade Coated OPV
![Page 12: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/12.jpg)
Spin Coated Blade Coated
Parameters • Time • RPM
• Blade speed and height • Substrate temperature
Efficiency • 2% (as-cast) • 5% (annealed)
• 3-4%
Pros • Higher efficiency • Extremely simple
• Greater parameter control • Industrially more practical • Less wasted materials
Cons • Industrially impractical • Limited parameter control • Wasteful
• Too many parameters • Lower efficiency
Thin Film Fabrication Methods
![Page 13: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/13.jpg)
PS:tol Study
0
200
400
600
800
1000
30 25 20 15 10 5
Film
Thickne
ss (n
m)
Blade Speed (mm/s)
50°C 60°C 70°C
0
100
200
300
400
500
600
15 10 5
Film
Thickne
ss (n
m)
Blade Speed (mm/s)
10 mg/mL 20 mg/mL 30 mg/mL
Thickness Measurements 20 mg/mL PS:tol
Thickness Measurements 10-30 mg/mL PS:tol
![Page 14: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/14.jpg)
5 mg/mL P3HT:tol Study
P3HT:tol at 5 mm/s
P3HT:tol at 10 mm/s
0
50
100
150
15 10 5
Film
Thickne
ss (n
m)
Blade Speed (mm/s)
60°C 70°C
Thickness Measurements AFM Roughness Measurements
![Page 15: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/15.jpg)
30 mg/mL P3HT:CB Study
0
200
400
600
800
1000
1200
1400
15 10 5
Film
Thickne
ss (n
m)
Blade Speed (mm/s)
80°C
Thickness Measurements AFM Roughness Measurements
P3HT:CB at 5 mm/s Annealed at 150°C for 20 min
P3HT:CB at 15 mm/s Annealed at 150°C for 20 min
5
2.5
-‐2.5
5
0
![Page 16: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/16.jpg)
90 mg/mL P3HT:CB Study Thickness Measurements AFM Phase Comparison
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
25 20 15 10 2.5
Film
Thickne
ss (n
m)
Blade Speed (mm/s)
80°C
P3HT:CB at 25 mm/s
P3HT:CB at 25 mm/s
Melted at 250°C and cooled
![Page 17: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/17.jpg)
30 mg/mL P3HT:PCBM Study
0
100
200
300
400
500
600
700
800
25 20 15 10 5
Film
Thickne
ss (n
m)
Blade Speed (mm/s)
80°C
Thickness Measurements
P3HT:PCBM at 5 mm/s
P3HT:PCBM at 5 mm/s
Melted at 250°C and quenched
AFM Phase Comparison
![Page 18: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/18.jpg)
Conclusion • Parameter Relationships: Film thickness is directly
proportional to substrate temperature, blade speed and solution concentration increase
• Film Morphology: Concentration dependent; slower blade speeds decrease roughness; annealing continues to decreases film roughness
• Crystallinity: Blade coating forms clustered P3HT pockets; melting and rapid quenching produces longer, more evenly distributed fibrils throughout P3HT:PCBM bilayer
![Page 19: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/19.jpg)
Next Steps
![Page 20: Thin Film Fabrication and Morphology Studies](https://reader031.vdocuments.us/reader031/viewer/2022020701/61f64cb376c92f426f430ae9/html5/thumbnails/20.jpg)
Acknowledgments Mike Brady
Justin Cochran
Chris Shuttle
Dr. Michael Chabinyc Dr. Alan Heeger
Dr. Frank Kinnaman
UCSB Materials Research Lab
California NanoSystems Institute
National Science Foundation