1. Polymer Crystallization on Curved Surfaces Steve Kuei

2. Overview Introduction –Organic electronics –Motivation Experimental –Previous work –Buckling Structures –Atomic Force Microscopy Conclusions Future work

3. Al Organic Electronics Solar Cells ITO

4. Motivation Polymer crystallization

5. Previous work A. Hexemer, V. Vitelli, E.J. Kramer, G. H. Fredrickson

6. Previous work A. Hexemer, V. Vitelli, E.J. Kramer, G. H. Fredrickson

7. Curvature Principal curvatures, Mean curvature – average of principal curvatures Gaussian Curvature – product of principal curvatures

8. Buckling Structures

9. Atomic Force Microscopy Wikipedia, by Askewmind Images by Vijay Narayan

10. AFM and buckling structures

12. P3EHT Polymer synthesized by Segalman Group, Berkeley M.W. 7k g/mol

13. P3EHT – spin coated

14. P3EHT – annealed for 12 hours

16. P3EHT – annealed for 2 days

17. Future work Film thickness –Currently too thick, pooling in trenches –Orientation underneath surface layer is unknown Buckling structures –Need to optimize amplitude and period of buckling structures so that polymer stays on the peaks –Need to control buckling structures to have regularly occurring gaussian curvature Conclusions –Gaussian curvature appears to dominate, especially after annealing for longer periods of time, aligning polymer fibers along the troughs.

18. Acknowledgements Princeton Environmental Institute Energy Grand Challenge MIRTHE/PCCM REU program Professor Loo, Professor Yao, Dr. Hexemer Eleni Pavlopoulou, Jongbok Kim, Stephanie Lee, Pilnam Kim, Rich Fiorillo, Atray Dixit, Vijay Narayan