Transcript of Microlens Array Light Trapping CdTe Solar Cells for use in Concentrator Photovoltaics Student:...
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- Microlens Array Light Trapping CdTe Solar Cells for use in
Concentrator Photovoltaics Student: Patrick Margavio, Mechanical
and Aerospace EngineeringFaculty Advisor: Dr. Hailung Tsai,
Mechanical and Aerospace Engineering Why Solar? Current energy
usage of the worlds 6.5 billion people is 13 Terawatts 1 The sun
outputs 120,000 TW Globally extractable wind power is 4 TW With
current efficiencies, fraction of land required to supply present
energy consumption is 1.35% of Earths landmass 2 Amount required
for food production is 13% cultivation, 26% pasture 2 Why
Concentrate Solar Energy? There are two basic strategies to compete
with fossil fuels Make solar inexpensive Copper indium gallium
diselenide, dye sensitized solar Commercially available single and
polycrystalline silicon Solar houses on campus Maximize efficiency
Combine solar cell (like multijunction GaAs) with solar
concentrator Mirrors, Luminescent Solar Concentrators Solar cell is
75% of cost of system Whats a Microlens Array? A microlens array is
a collection of microscopic lenses assembled in an orderly pattern
Focuses light into a periodic pattern Two purposes for us Light
less likely to reflect off top surface Incident light intensity
increased locally Efficiency increases with increased intensity It
is expensive to create microlens arrays Decrease expense by
creating a Foturan glass mold and then using it to make many cheap
silicon films Mold is created by laser machining G code used to
computer control process is shown After laser machining Foturan
glass is baked at 500 0 C and then at 600 0 C. After baking, sample
is etched with HF acid After etching sample is annealed for another
hour Making the Microlens Array Mold: What is Light Trapping? There
are two basic ways to trap light within a solar cell Reducing the
amount of light reflected away from top surface Examples below
scatter incoming light to reduce reflection 3 Preventing light from
leaving once it has entered CdTe Cell Fabrication: Transparent
Conducing Oxide (TCO) purchased from Pilkington (TEC C10) 150 nm
CdS film chemically deposited on TCO 5 m CdTe film deposited on CdS
Sample dipped in CdCl 2 Sample rinsed with methanol Making the
Silicon Microlens Array: The silicon gel used is
Polydimethylsiloxane (PDMS) PDMS is combined with a curing agent
The PDMS mixture is poured over the glass mold Sample is placed in
a vacuum chamber (right) to remove bubbles from mixing process Next
PDMS is cured at 70 0 C for one hour in a furnace to solidify To
left, a microscope image of the silicon film is visible. Below, the
glass mold is shown in the silicon gel Acknowledgements: Dr Hailung
Tsai Dr Cheng-Hsiang Lin Material Research Center Intelligent
System Center References: 1)P. V. Kamat. J. Phys. Chem. C 111,
2834-2860 (2007) 2)A. Luque. Journal of Applied Physics 110, 031301
(2011) 3)V. V. Iyengar, B. K. Nayak, M. C. Gupta. Solar Energy
Materials and Solar Cells 94, 2251-2257 (2010) Demonstration Model
We will implement our solar cell design to power a small electronic
device A two square inch solar cell can produce around 10 to 11 W
of power (based on commercially available silicon solar technology)
The current output can be a limiting factor for solar cell designs
We chose a 7 inch digital picture frame, which fits this power
output to power with the 2 inch solar cell design