Organic hybrid thermoelectric materials

1. THERMOELECTRIC
MATERIALS
By
Vijitha I
Junior Research Fellow
CSIR-NIIST

2. 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

3. 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)

4. POWER GENERATION/ REFRIGERATION

5. THERMOELECTRIC EFFICIENCY
Thermoelectric Figure Of Merit

6. SEEBECK COEFFICIENT
Open circuit voltage produced per unit temperature
difference (Thermo EMF)
V

T
 
From transport calculations in nanoscale




B C F  




E E
K
 n
K T
e
B

7. THERMOELECTRIC MATERIALS
The good thermoelectric materials should possess

8. 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
EF
EV
N-type
α σ

9. 2
α 
ZT T


INTERRELATION
Figure of merit

LT e 





B C F  




E E
K
 n
K T
e
B
Wiedemann-Franz Law
Seebeck coefficient

10. THE SWEET SPOT
Semiconductor
Semimetals &
highly doped
semiconductor
s
Metals

11. 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

12. APPLICATIONS OF TE MATERIALS
RTG
Mars Science Laboratory Thermoelectric converter module
Thermoelectric generator