Crystallization of TES ADT in
Constrained Channels
Abby Grosskopf, Anna Hailey, Lynn Loo
Loo Lab Group: Polymer and Organic Electronics Laboratory
Princeton University
Background Information
Organic Semiconductor: An organic material with an electrical
conductivity
Benefits of using organic semiconductors over inorganic semiconductors:
- Solution-processable
- Inexpensive to fabricate
- Suitable for large area processing
Thin films comprising organic molecules have promising applications,
such as organic thin film transistors, and solar cells.
http://www.sigmaaldrich.com/technical-documents/articles/materialmatters/organic-materials.html
http://www.sunnysolarlightgarden.com/solar-yard-lights-work/
Crystallization of TES ADT
TES ADT is a solution-processable organic semiconductor.
TES ADT undergoes spherulitic growth when spin coated from 2 wt%
solution in toluene then exposed to 1,2-dichloroethane vapor.
Spin-coat from 2 wt%
solution in toluene
Expose to
1,2-dichloroethane vapor1
as-spun film
crystallized film
Lee, Stephanie. (2012). Processing-Structure- Function Relationships In Solution-Processed , Organic-Semiconductor Thin Films for Transistor
Applications. Ph.D. Thesis. Princeton University.: US.
Graphics thanks to Anna Hailey
TES ADT and Guiding Crystallization
• Utilizing differences in TES ADT growth rate on SIO2 vs PFBT-treated
Au, growth can be specified along channels.
• Guiding crystallization allows us to pattern TES ADT into predefined
pathways which can potentially have applications in organic
electronics.
Lee, Stephanie. (2012). Processing-Structure- Function Relationships In Solution-Processed , Organic-Semiconductor Thin
Films for Transistor Applications. Ph.D. Thesis. Princeton University: US.
My Project
What are the limits to guiding growth of TES ADT on patterned substrates?
What is the smallest feature size that we can pattern with TES ADT?
By understanding more about the growth of TES ADT in channels, we
hope to pattern electronics in more elaborate and efficient ways to create
new devices and save energy.
Haataja’s Group Predictions
Sri Muralidharan’s PhD Thesis:
V denotes the growth rate, M denotes mobility , Γ denotes interfacial
forces, E denotes the bulk driving force of crystallization, κ denotes
interfacial curvature, and w denotes channel width.
Muralidharan, Srevatsan. (2012). Continuum Studies of Microstructure Formation in Metallic and Organic Thin Films. Ph.D.
Thesis. Princeton University: U.S.
TES ADT Growth in Channels
1000um
TES ADT Growth into Corners
1000um
Alta Fang’s Predictions
No TES ADT Leaking Out of Corner:
TES ADT Leaking Out of Corner:
Instantaneous Velocity vs. 1/(width of pattern at growth
front)
The crystal
growth outside
of the pattern
will always
drag the crystal
growth front up
and over the
corner.
Results: Different Corners
Growth Rate of TES ADT Growth Into Corners
( Bulk Driving Force May Increase)
20
18
16
Speed (um/s)
14
12
PFBT
10
Corner 1
8
Corner 2
Corner 3
6
4
2
0
0
0.1
0.2
0.3
0.4
Inverse Width (1/um)
Critical Widths: 1.7 um, 2.0 um, 2.5 um
0.5
0.6
0.7
Results: Channel and Corner Data Combined
TES ADT Growth Rate Into Channels and
Corners
25
Growth Rate (um/s)
20
15
PFBT
Corners
10
Channels
5
0
0
0.1
0.2
0.3
0.4
Inverse Width (1/um)
0.5
0.6
0.7
Using the predicted equation, the averaged critical channel width is 2 um.
Closing Remarks
- Learned new lab techniques, data analysis skills, and
the fundamentals of day-to-day laboratory research
- Gained a new perspective on the vast amount of
applications of chemical engineering in scientific
research
- Looking forward to using what I learned this summer
in future independent work!
Special Thanks to: