Jonathan Chan
EE 422 Polymer Electronics Lab
2/4/09
Week 4: Polymer Solution Preparation (revised)
Prior to making vias on the substrate, the polymer solution is prepped to ensure the correct amount of
polymer (OC1C10-PPV) is added to the solution. Begin by measuring the specified amount of polymer
(approximately 50mg unless otherwise stated). The sample calculation of polymer needed is shown
below:
Given: 10ml (solvent) at 0.5%
1g = 1ml
10 mg solution x 0.5% = x
X = 0.51mg of polymer solution for 11 students
To weigh the correct amount of polymer solution, place a clean empty bottle on the scale inside the
glove box and zero the scale. Zeroing the scale allow for proper calibration of the scale and the objective
being weighed. Transfer the polymer into the empty bottles and place the bottles through the center
ante chamber. Remember that in the previous step, the ante chamber depressurizes and
decontaminates the surrounding air inside the chamber. The pressurized glove box protects the air
sensitive cathode and protects us from the hazardous solvents. Once in the spinning glove box, add the
polymer into the clean empty bottle labeled with the date, mg/ml, and % information. Clear labeling
allows for proper identification of when the solvent was made and proper storage. In the lab we
measured the precise amount of polymer (OC1C10-PPV) = 0.512mg with a temp of 50° and a stir speed
of 400rpm.
Polymer
OC1C10-PPV
Mass (mg)
51mg
Solvent(Toluene)
10.2ml
THF
0ml
Solution Temp
50°
Stir Speed
400rpm
Start Time
2:39pm
Table 1: Solution Preparation Process Flow Table
The 10ml solution contains only .51ml of polymer and 9.49ml of toluene. Although THF does help the
“jello” process in room temperature, (process of solidifying the solution), pure toluene gives better
brightness to the LED. Be sure that the tip of the syringe is upside down to release any remaining air
bubbles and solution. As stated previously, air bubbles can affect the polymer film. When adding the
toluene syringe, be sure to draw the exact amount of solvent and release all existing air bubbles by
tipping the syringe upside down. Now the complete polymer solution is ready to mix. The reason this
polymer solution process is conducted a day prior to the lab is due to the mixing cycle. The solution is
mixed on the hot plate (at 50°) overnight at half speed to properly produce a filtered polymer solution.
The spinning process begins the drying process turning the solution into a solid layer. Although the
spinning process creates a high vapor pressure for the solvent, placing the lid 1mm above the substrate
and then spinning it in the spin coater helps slow down the drying process. Then expose the filtered
solution to the spin coat process again inside the glove box in preparation for the vias.
Jonathan Chan
EE 422 Polymer Electronics Lab
2/4/09
Via is a term used for a makeshift hole between the conductive layer of calcium and ITO. The vias are
needed to make an electrical contact with each electrode for each OLED present on the substrate. This is
a delicate procedure due to the proper placement of each via. Since the distance between the ITO pads
are only 1mm apart, the via needs to make proper contact with the calcium layer without damaging that
1mm gap. Figure 3 below shows the proper position of the via.
ITO
VIA
1mm Gap
Calcium
ITO
PU
Figure 3: Making a Via
When making the vias, ensure that the substrate is NOT facing in the “UP” direction. Having the
substrate upside down allows the scratching of the via seen through the glass substrate. By making the
vias with the substrate in the “UP” position, the tweezers can block proper vision of how deep it is
penetrating.
Week 5: Sustainability Issues
Sustainability has many definitions. My interpretation of sustainability is a process of maintaining a
constant state without altering future needs. This ultimately means innovation with the concept of
“green” conservation and lessening of carbon footprints. In relation to engineering, “sustainability
describes a condition in which natural systems and social systems survive and thrive together
indefinitely” [2]. Due to important ecological problems such as pollution and global warming,
implementing sustainable engineering practices can contribute to sustainability. As a result, there is a
growing trend for sustainable and socially responsible products and services. Societies such as the
Intergovernmental Panel on Climate Change (IPCC) monitor the effects of climate change due to human
activity. IPCC assesses scientific literature to study impacts on human-induced climate change and
options for adaptation and mitigation. The IPCC and many others societies offer sustainability through
ecosystem services. Ecosystem services are benefits from resources and processes supplied by nature.
Three main concepts associated with ecosystem services are provisioning, regulating, and cultural.
Provisioning incorporates food, water, and the energy to survive. Regulation is climate variation, any
changes in climate mitigating diseases through storms. Cultural is the benefits of recreation and
religion. The distinctive property of ecosystem services is that human demand of natural products in the
case of clean drinking water or renewable energy. We are beginning to exceed earth’s ecological
Jonathan Chan
EE 422 Polymer Electronics Lab
2/4/09
capacity requiring new innovations and advantages in technology and science. By fabricating sustainable
products, such as a polymer OLED, saving water and energy saves money and reduces environmental
impact. There are four main concepts or “laws” of sustainability:




Everything connects to everything else
Everything must go somewhere
Nature knows best and bats last
There is no such thing as a free lunch [2]
Implementing these concepts help reduce and possibly eliminate environmental waste saving cost and
materials during fabrication. An example of this is when measuring exact polymer use (.51mg) when
preparing the polymer solution last week. By attending ASI expansion sustainability seminar, current and
future building practices will hopefully help Cal Poly ensure energy efficiency. I hope to learn more
about the importance of sustainability and its contribution in engineering.
References:
[1]
S. R. Euston and W. E. Gibson, “The Ethic of Sustainability,” Earth Ethics 6, 1995 p. 5-7. Available:
http://www.iisd.org/sd/principle.asp?pid=31&display=1. [Accessed Jan. 16, 2009].
[2]
http://courseware.ee.calpoly.edu/~dbraun/courses/IEEE-EE422-Reports.doc.