thermoelectric materials
TRANSCRIPT
THERMOELECTRIC
MATERIALS
By
Vijitha I
Junior Research Fellow
CSIR-NIIST
PIONEER IN THERMOELECTRICS
Instrument used by Seebeck to observe the
deflection of a compass needle (a) due to a
thermoelectric induced current from heating
the junction of two different metals (n and o).
Thomas Seebeck
THERMOELECTRICITY
Temperature difference across a solid produces
thermally generated emf which can drive current
through a load (power generation)
Driving current through the same solid results in
heating in one contact and cooling in another
(refrigeration)
POWER GENERATION/ REFRIGERATION
THERMOELECTRIC EFFICIENCY
Thermoelectric Figure Of Merit
SEEBECK COEFFICIENT
Open circuit voltage produced per unit temperature
difference (Thermo EMF)
T
V
n
TK
EE
e
K
B
FCB
From transport calculations in nanoscale
THERMOELECTRIC MATERIALS
The good thermoelectric materials should possess
DESCRIPTION OF THE PROBLEM
Electron mobility is low for organic materials
Getting ZT for n-type and p-type TE materials at
same temperature
α σ
EC
EV
EF
N-type
α σ
TZT
α2
INTERRELATION
LTe
n
TK
EE
e
K
B
FCB
Wiedemann-Franz Law
Figure of merit
Seebeck coefficient
THE SWEET SPOT
Semiconductor
Semimetals &
highly doped
semiconductor
s
Metals
PROPOSED PLAN
Fabrication of hybrid materials
Understand underlying physics
Designing polymer composite based TE materials
and refrigeration modules
Roll-to-roll printable TE circuitries
Low power rating TE refrigerators compactable with
low cost organic solar cell
To be competitive, ZT should be ~ 0.5
APPLICATIONS OF TE MATERIALS
RTG
Thermoelectric converter moduleMars Science Laboratory
Thermoelectric generator