Crystallization of Small Molecules for Organic Electronic Applications Jessica Lynn Saylors, Anna Hiszpanski, and Yueh-Lin (Lynn) Loo 07 October 2011 Summer of Learning Symposium 2011 Jessica Lynn Saylors, Anna Hiszpanski, and Yueh-Lin (Lynn) Loo 07 October 2011 Summer of Learning Symposium 2011

Why organic electronics? Mechanically Flexible Large Area Chemical Versatility

Transistors – Building Blocks of Organic Electronics organic semiconductor gate + dielectric source drain How an Transistor works SD Organic Insulator Gate electrode 0 V -1 V0 V-5 V 0 V -5 V Cut-off regime Linear regimeSaturation regime Organic field-effect transistor (OFET)

Xiao, S. et al. Angew. Chem. Int. Ed Contorted Hexabenzocoronene (HBC) HBC

Crystallizing HBC Thin Films π stacking π-face HBC Amorphous HBC Partially Crystallized HBC

Thermal Evaporation Thickness Gradient: 15nm – 250nm

HBC Mobility vs. Thickness

Macroscopic Morphology 15nm 33nm 50nm 120nm

Optical Micrographs for Kinetics Analysis HBC thin film - annealed at 240°C t = 0.5 mint = 1 mint = 1.5 min t = 2 mint = 2.5 mint = 3 min

Avrami Kinetics n: variable that gives some indication regarding mode of crystallization K: indication of the rate of crystallization %crystallized

Avrami n vs. Thickness

American Institute of Chemical Engineers

Acknowledgments Loo Group –Anna Hiszpanski –Professor Loo Princeton Environmental Institute Siebel Energy Grand Challenge Loo Group, March 2011