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Arun Majumdar, UC Berkeley
Challenges and Opportunities in Thermoelectric Energy Conversion
Arun Majumdar
Department of Mechanical EngineeringUniversity of California, Berkeley
Materials Sciences DivisionLawrence Berkeley Lab
DOE, NSF, ONR, NASA
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Arun Majumdar, UC Berkeley
Thermoelectricity and Energy Conversion
ab
V
T1 T2
aSeebeck Coefficient, S = V/∆T
Peltier Coefficient, π = Q/I=ST
pnpn
R
Qin
Qout
Qin
Tcold
Thot
pnpn
QoutI
V
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Arun Majumdar, UC Berkeley
Thermoelectric Figure of Merit
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Arun Majumdar, UC Berkeley
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Arun Majumdar, UC Berkeley
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Arun Majumdar, UC Berkeley
Courtesy: Gang Chen
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Arun Majumdar, UC Berkeley
Origins of Thermoelectricity
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Arun Majumdar, UC Berkeley
Effect of Nanostructuring on S2σ
(Dresselhaus et al., 1993)
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Arun Majumdar, UC Berkeley
Majumdar, Science 303, 777 (2004)
PbSeTe/PbTe QD Superlattices
Harman et al., Science 297, 2229 (2002)
AgPb18SbTe20ZT = 2 @ 800K
AgSb rich
Hsu et al., Science 303, 818 (2004)
kTSZT σ2
=
Venkatasubramanian et al. Nature 413, 597 (2001)
Bi2Te3/Sb2Te3 Superlattices2.5-25nm
kbulk = 0.49 W/m-Kkns = 0.22 W/m-K
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Arun Majumdar, UC Berkeley
k [W
/m-K
]
A B
Alloy Limit
Alloy limit of thermal conductivity in crystalline materials!
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Arun Majumdar, UC Berkeley
Li et al., Appl Phys Lett 83, 3186 (2003)
Deyu Li, Yiying Wu, Rong Fan, Peidong Yang
Nanowire
Si/SiGe superlattice nanowires
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Arun Majumdar, UC Berkeley
ErAs Nanostructures Embedded in InGaAs
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Arun Majumdar, UC Berkeley
InGaAs
ErAs/InGaAs
Woochul Kim, Pramod Reddy, Josh Zide, Art Gossard
Below Alloy Limit!
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Arun Majumdar, UC Berkeley
k =
d
dTeb ω( )Planck BB1 2 3 v ω( )
Speed{ l ω( )
MeanFreePath{ dω
0
ωmax
∫⎡
⎣
⎢ ⎢
⎤
⎦
⎥ ⎥
Frequency, ω ωmax
eb
v
Atoms/Alloys
Nanostructures
Phonon Scattering
Hypothesis
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Arun Majumdar, UC Berkeley
Courtesy: Ed Croke, Hughes Res. Lab. for materials
Si-Ge Superlattices
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Arun Majumdar, UC Berkeley
Cathode
Barrier
Anode
Metallic contact for
top connection
100 microns
Courtesy: John Bowers (UCSB); Ali Shakouri (UCSC)
SEM Picture of Thin Film Coolers
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Arun Majumdar, UC Berkeley
X. Fan, G. Zeng, C. LaBounty, E.Croke, C. Ahn, J.E. Bowers, A. Shakouri, “SiGeC/Si superlattice micro cooler,” Applied Physics Lett., Vol. 78, No.11, 12
March 2001.Featured in Nature Science Update, Physics Today, AIP April 2001
n-Si/SiGeC Superlattice Micro Cooler
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Arun Majumdar, UC Berkeley
G. Zeng, X. Fan, C. LaBounty, J.E. Bowers, E.Croke, J. Christofferson, D. Vashaee, A. Shakouri, “Direct Measurement of Cooling Power Density for Thin Film Suplerlattice Micro Coolers,” submitted to APL 2002.
Micro Refrigerator Integrated with Thin-Film Heater
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Arun Majumdar, UC Berkeley
Localized control of temperature on the chip.
InP-based Micro Refrigerator & Micro Heater
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Arun Majumdar, UC Berkeley
Nanowire Array Composites and Devices
2 µm
200 nm
Majumdar Lab, UC Berkeley
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Arun Majumdar, UC Berkeley
Majumdar, Science 303, 777 (2004)