Polymer Crystallization on Curved Surfaces Steve Kuei
Overview Introduction –Organic electronics –Motivation Experimental –Previous work –Buckling Structures –Atomic Force Microscopy Conclusions Future work
Al Organic Electronics Solar Cells ITO
Motivation Polymer crystallization
Previous work A. Hexemer, V. Vitelli, E.J. Kramer, G. H. Fredrickson
Previous work A. Hexemer, V. Vitelli, E.J. Kramer, G. H. Fredrickson
Curvature Principal curvatures, Mean curvature – average of principal curvatures Gaussian Curvature – product of principal curvatures
Buckling Structures
Atomic Force Microscopy Wikipedia, by Askewmind Images by Vijay Narayan
AFM and buckling structures
P3EHT Polymer synthesized by Segalman Group, Berkeley M.W. 7k g/mol
P3EHT – spin coated
P3EHT – annealed for 12 hours
P3EHT – annealed for 2 days
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.
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