Leveraging the Experimental Method to Inform Solar Cell Design

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Leveraging the Experimental Method to Inform
Solar Cell Design

• Mary Annette Rose
• Jason Ribblet
• Heather Hershberger
• International Technology Education Association
• February 22, 2008, 200-250, Room 251E

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Science-Technology Enterprise
Symbiotic Relationship
Mutual Dependence
Images The School of Science and Engineering,
The University of Waikato. Retrieved
http//sci.waikato.ac.nz/about_the_school.shtml
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Thin-Film Solar Cells

• Collaboration of the National Renewable Energy
  Laboratory Heliovolt to develop a solar cell
  using a copper-indium-gallium selenide (CIGS)
  semiconductor.
• Scientific challenge to understand the chemistry
  and microscopic structure of the material in
  order to optimize its electrical properties.
• Engineering challenge develop a reliable
  manufacturing processakin to a printing process
  that produces standard size modules (15 30-cm
  wide).

Bullis, K., (2007). Making cheaper solar cells.
Technology Review. Wednesday, September 12, 2007.
Retrieved January 23, 2008, from
http//www.technologyreview.com/Energy/19369/page1
/
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Challenge for Technology Education
Science Content Process
Technology Content Process
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Presentation Goal
Photochemistry
Solar Cells
Inquiry Experimentation
Design
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Cuprous Oxide Solar Cell
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Observing Phenomena

• Stimulate intellectual curiosity
• What is happening in this system?
• What energy is at work here?
• What are the inputs, processes, and outputs of
  the system?
• What happens if we block the cell from the sun?
• What happens when we reverse the probes of the
  multimeter on the plates of the cell?

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Solar Cell Photoelectric Effect
Parts Materials List Parts Materials List Parts Materials List Parts Materials List Parts Materials List
Component Function Parts Material Qty - Size
Case Watertight transparent housing Front/Back 1/8 Acrylic 2 pcs of 4 1/8 x 4 1/8
Case Watertight transparent housing Sides/Bottom 1/8 Acrylic 1 pc of ½ x 12
Case Watertight transparent housing
Plates Anode and Cathode Cuprous Oxide Cupric Oxide 0.20 Copper, Unpolished 2 pcs of 3 7/8 x 5
Salt Solution Medium of ion exchange Salt (NaCl reagent grade) 15 NaCL or 17.6 g
Salt Solution Medium of ion exchange Distilled Water 85 H2O or 100 ml
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Challenge Students to

• Take on the role of a photochemist
• Learn how solar cells convert light into
  electricity
• Inform cell design

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Photochemistry is

• study of chemical reactions of molecules in
  excited states produced by the absorption of
  light energy, i.e., photon
• infrared (7001000 nm)
• visible (400700 nm)
• ultraviolet (200400 nm)
• electron transfer and ionization

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Challenge Students to

• Take on the role of a photochemist
• Learn how solar cells convert light into
  electricity
• Inform cell design
• Plan, implement, and interpret an experiment

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Experiment Method for Investigating Variables

• To what extent does the distance from the light
  source effect the power production of solar cells?

Cause
Effect
Independent Variable
Dependent Variable
Outcome Variable
Treatment Variable
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What variables influence the power output of the
cell?

• List Variables
• Identify Elements
• Concentration of salt solution
• Distance between plates (E)
• Surface area of plate (Cu2O and CuO)
• Type of light (frequency)
• Intensity of the light
• Thickness of copper plate

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What question might we experimentally test?
Variables Question
Concentration of salt solution Distance between plates (E) Surface area of plate (Cu2O and CuO) Type of light (frequency) Tilt of cell to light source Intensity of the light Thickness of copper plate Type of plate How does the concentration of the salt solution (IV) effect the electrical power output (DV) of the cell? How does the concentration of the salt solution (IV) and the tilt of the cell (IV) effect the electrical power output (DV) of the cell?
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Form Teams and Assign to Treatment Conditions
Sam Bob Inga
Fran Ted Harry
Treatment Group 1 5 Solution
2
1
Ted Laura Elsa
Howard Sally Frank
Treatment Group 2 15 Solution
3
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Martha Rex Harris
Bill Jean Remi
Treatment Group 3 25 Solution
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5
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Day 2 3 Manufacture Cells

• Specifications
• Top/Back C x B
• Side D x (2BC)
• Plate F x A
• A 5
• B 4 1/8
• C 4 1/8
• D 1/2
• E 3/16
• F 3 7/8

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Homework Literature Review

• Students discover more about
• semi-conductive materials,
• the photoelectric effect,
• the interaction of energy and materials,
• and
• solar (photovoltaic) cells.

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Day 2 3 Manufacture Cells Process Sheet
Metal
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Chemical Safety
Hazards Safety Practices
Nitric Acid (oxidizing agent) corrosive and reactive, teacher should prepare and handle the solution, store alone in storage cabinet Acrylic Adhesive methylene chloride volatile inhalation hazard skin irritant Cupric oxide (black powder) skin irritant Handle in a well-ventilated area. Wear chemical splash goggles. Wear neoprene gloves and clothing protection. If directly exposed, flush the affected area with water.
For laboratory safety, see the National Institute
for Occupational Safety (NIOSH, 2006).
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Heat Copper Plate
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Heat Promotes Copper Oxidation
Type Formula Color Photoelectrical Property
Copper I oxide cuprous oxide Cu2O Red Photovoltaic
Copper II oxide cupric oxide CuO Black
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Layer of Cupric Oxide (Black)
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Acrylic Processing
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Assemble the Case
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Test for Leaks
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Day 4 Procedure for Data Gathering

• Stimulate planning
• What procedure will we use to test the cells?
• How can we assure systematic and consistent
  testing conditions?
• Why does a scientist strive for consistent
  experimental conditions?

Set-UP
Measuring
Recording
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Procedure for Data Gathering
Setting-up Measuring Recording
Specify light source Relative position of cell to light source Charging the cell Attaching alligator clips/probes to multimeter Adjusting function range Reading meter
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Data Analysis
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Recording Data
Treatment IV-1 Treatment IV-2 Dependent DV-1 Dependent DV-2 Dependent DV-3
Team Salt Solution (IV-1) Angle of Test (IV-2) Voltage (mV) Current (µA) Power (mW)
1 5 30
2 5 45
3 15 30
4 15 45
5 25 30
6 25 45
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Data Gathering
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Recording Data
Treatment IV-1 Treatment IV-2 Dependent DV-1 Dependent DV-2 Dependent DV-3
Team Salt Solution (IV-1) Tilt (IV-2) Voltage (mV) Current (µA) Power (µW)
1 5 90 22 88 1.94
2 5 45 10 74 0.74
3 15 90 45 346 15.57
4 15 45 29 282 8.18
5 25 90 40 216 8.64
6 25 45 30 192 5.76
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Interpreting the Results

• Level of salt in the solution impacts performance
  with best performance occurring at 15
• Tilt impacts performance with 90 tilt
  (perpendicular) consistently position resulting
  in best performance
• The best performing combination of factors was a
  15 solution at 90 tilt

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The Photoelectric Effect
h Plancks Constant v frequency 1 eV 1.6
x 10-19 joules
Yaqoob, T. (n.d.). Photoelectric effect Image.
John Hopkins University. Retrieved from
http//www.pha.jhu.edu/yaqoob/8m/lecture2/photoel
ectric_1.gif
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Atomic States Ground vs. Excited
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What is happening in the solar cell?

• Excitation of a Cu2O
• Negatively charged ions move through circuit,
• Positively charged ions break free, and
• Combine on the raw copper plate.

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Solid State PV Cell
Michell, R. (2000). A Seimens crystalline PV
cell. WisconSUN. Retrieved from
http//www.wisconsun.org/learn/learn_intro.shtml
Renewable Energy Works. (n.d.)
Photovoltaics.Image. Retrieved 3/10/06, from
http//www.renewableenergyworks.com/pv/PVDefn/PVDe
fn.html
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Learn More
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Lets Make Connections Review !!
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Alignment to National Standards
Standards for Technological Literacy (ITEA, 2000) National Science Education Standards (NRC, 1996)
Inquiry Experi-mentation 10. Students will develop an understanding of the role of troubleshooting, research and development, invention and innovation, and experimentation in problem solving. As a result of the activities in grades 9-12, all students should develop Abilities to do scientific inquiry Understanding about scientific inquiry
Energy 16. Students will develop an understanding of and be able to select and use energy and power technologies. As a result of the activities in grades 9-12, all students should develop an understanding of Structure and properties of matter Chemical reactions Interactions of energy and matter
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Characteristics of Experimental Designs

• Pose a research question which identifies the
  treatment (IV) and an outcome (DV) variable.
• Select assign a sample to treatment conditions
• Experimental group (Receives treatment)
• Control group (No treatment)
• Comparison groups (Different Levels of treatment)
• Apply treatment to one or more groups
• Control extraneous variables
• Measure outcomes
• Statistically describe and represent the data
• Statistically test the hypothesis

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Inquiry is a Search for Understanding

• Spurred by intellectual curiosity
• Process is characterized by
• observing phenomena
• asking questions and hypothesizing
• systematically gathering and analyzing data
• theorizing about the meaning of the evidence
• Enabled by objective, measurable, and replicable
  methods

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Best Practices Scaffolding

• Initiate intellectual curiosity
• Ask questions, and encourage students to form
  questions
• Provide increasingly more complex models
  (conceptual-to-realistic) of the photoelectric
  effect
• Provide visual examples and simulations of
  photochemical processes
• Provide access to diverse resources, e.g.,
  chemistry and physics
• Guide students through experimentation sampling,
  hypothesizing, identifying variables, planning
  procedures, analyzing data, interpreting data
• Require sense-making activities, such as
  collaborative discussion and the creation of
  cause and effect diagrams
• Require students to apply experimental findings
  to the re-design of a solar cell.

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Contact .

• Mary Annette Rose
• Ball State University
• arose_at_bsu.edu
• 765-285-5648
• http//arose.iweb.bsu.edu

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Leveraging the Experimental Method to Inform
Solar Cell Design

• Mary Annette Rose
• Jason Ribblet
• Heather Hershberger
• International Technology Education Association
• February 22, 2008, 200-250, Room 251E

M.A. Rose, 2008