Crystallization of Small Molecules for Organic Electronic Applications
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Transcript of Crystallization of Small Molecules for Organic Electronic Applications
Crystallization of Small Molecules for Organic Electronic
ApplicationsJessica Lynn Saylors, Anna Hiszpanski, and Yueh-Lin (Lynn)
Loo
07 October 2011Summer of Learning Symposium 2011
Why organic electronics?
• Mechanically Flexible
• Large Area
• Chemical Versatility
www.plasticlogic.com
Transistors – Building Blocks of Organic Electronics
organic semiconductor
gate + dielectric
source
drain
How an Transistor works
S D
Organic
Insulator
Gate electrode
0 V 0 V 0 V -1 V 0 V -5 V
0 V -5 V -5 V
- - - - - - - - -+ + + + + + + + +- - - - - - - - -+ + + + + + + + + + + + + + ++ +
- - - - - - - - -+ + + + + + + + +- - - - - -
Cut-off regime
Linear regime Saturation regime
Organic field-effect transistor (OFET)
Xiao, S. et al. Angew. Chem. Int. Ed. 2005.
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
46 48 50 52 54 563.03.54.04.55.05.56.06.57.07.5
Mob
ility
*10-4
(cm
2 /Vs)
Estimated Thickness (nm)
Macroscopic Morphology
15nm
33nm
50nm
120nm
Optical Micrographs for Kinetics AnalysisHBC thin film - annealed at 240°C
t = 0.5 min t = 1 min t = 1.5 min
t = 2 min t = 2.5 min t = 3 min
Avrami Kinetics
n: variable that gives some indication
regarding mode of crystallization
K: indication of therate of crystallization
%crystallized
0 20 40 60 80 100 120 140 160 180
0.5
1.0
1.5
2.0
2.5
3.0
3.5
227C 240C 255C
n
Thickness (nm)
Avrami n vs. Thickness
0 20 40 60 80 100 120 140 160 180
0.5
1.0
1.5
2.0
2.5
3.0
3.5
227C 240C 255C
n
Thickness (nm)
Avrami n vs. Thickness
American Institute of Chemical Engineers
http://www.aiche.org/Students/Conferences/national.aspx
http://www.minneapolisconventioncenter.com/
Acknowledgments
• Loo Group– Anna Hiszpanski– Professor Loo
• Princeton Environmental Institute
• Siebel Energy Grand Challenge
http://www.princeton.edu/pei/
Loo Group, March 2011