Nanostructured Bismuth Telluride Thin Films - Advancing the Capability of Thermoelectric Materials

Lead Research Organisation: University of Southampton
Department Name: Sch of Chemistry

Abstract

Thermoelectric (TE) materials can be used to convert thermal energy into electricity. Their properties are based on one of two phenomena, the Seebeck effect (for power generation) and the Peltier effect (for electronic cooling or heating). A TE device is formed when an n-type doped material is connected electrically in series and thermally in parallel across a temperature differential to a p-type doped material, so that current flows between the two. TE generators have a number of very favourable features as they offer solid-state operation, have no mechanical parts that can wear out, require little maintenance, have long lifetimes, produce zero emissions and are compact compared with heat engines. Despite this, currently they are used only in niche applications because of the low thermoelectric efficiency of the existing materials.

Solid state TE devices offer a promising route to efficient and sustainable electrical power harvesting from low grade waste heat produced in internal combustion engines, and in energy-intensive industrial processes, for example refineries and glass furnaces. For low temperature waste heat and natural heat sources, there is no competing technology, thus a huge opportunity exists. However, key barriers need to be overcome in order to make the application of TEs in these areas practicable, particularly to increase the thermoelectric efficiency and reduce the material volume required to create functional TE devices. Nanostructuring TE materials can lead to very significant increases in efficiency (due to both quantum confinement effects and reductions in lattice thermal conductivity). An important target, therefore, is the development of low-cost methods by which nanostructured thermoelectric materials can be produced.

Bismuth telluride, Bi2Te3, is a narrow band gap semiconductor whose alloys are commonly used in commercial TE devices as they have among the best room temperature thermoelectric properties of known bulk materials. It has been demonstrated that nanostructuring of thermoelectric materials can lead to significant increases in efficiency. A key current limitation at present is in achieving precise spatial control of material growth, morphology and orientation on the nanoscale. Under a project funded by STFC we have developed a novel single source chemical vapour deposition (CVD) reagent and method that significantly enhances the ability to deposit high quality thin films of Bi2Te3 TEMs with very high area selectivity onto micropatterned surfaces. This application is focussed on achieving key milestones to establish the commercial potential of this deposition method, with the target of increasing the thermoelectric figure of merit (ZT) to ca. 2, which would mean energy harvesting from industrial plants would be achievable.

Publications

10 25 50
 
Description We were able to demonstrate that our molecular (single source) precursor compounds are extremely effective for highly selective chemical vapour deposition of bismuth telluride and antimony telluride onto lithographically patterned surfaces, with enhanced affinity for growth on TiN over SiO2. We also demonstrated that by combining two related precursor sources, it is possible to grow thin films of the single phase, ternary material Bi2Te(3-x)Se(x) with good control over composition and corresponding electrical properties. This is important for optimising these materials for thermoelectric applications. We have further used our selective deposition method to create arrays n-type and p-type thermoelectric elements on microarrays to produce device prototypes and begun determining their TE properties.
Exploitation Route We intend to take this work forward for incorporation into thermoelectric microdevices primarily for energy harvesting applications, in partnership with commercial organisations - proposal funded via STFC.
Sectors Electronics

Energy

Environment

URL http://www.southampton.ac.uk/chemistry/research/projects/selective-chemical-vapour-deposition-of-chalcogenide-semiconductors.page?
 
Description STFC IPS
Amount £363,000 (GBP)
Funding ID ST/P00007X/1 
Organisation Science and Technologies Facilities Council (STFC) 
Sector Public
Country United Kingdom
Start 09/2016 
End 10/2019
 
Title CCDC 1022738: Experimental Crystal Structure Determination 
Description Related Article: Sophie L. Benjamin, Yao-Pang Chang, Chitra Gurnani, Andrew L. Hector, Michelle Huggon, William Levason, Gillian Reid|2014|Dalton Trans.|43|16640|doi:10.1039/C4DT02694B 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
URL http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/cc13b7k7&sid=DataCite
 
Title CCDC 1022739: Experimental Crystal Structure Determination 
Description Related Article: Sophie L. Benjamin, Yao-Pang Chang, Chitra Gurnani, Andrew L. Hector, Michelle Huggon, William Levason, Gillian Reid|2014|Dalton Trans.|43|16640|doi:10.1039/C4DT02694B 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
URL http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/cc13b7l8&sid=DataCite
 
Title CCDC 1022740: Experimental Crystal Structure Determination 
Description Related Article: Sophie L. Benjamin, Yao-Pang Chang, Chitra Gurnani, Andrew L. Hector, Michelle Huggon, William Levason, Gillian Reid|2014|Dalton Trans.|43|16640|doi:10.1039/C4DT02694B 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
URL http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/cc13b7m9&sid=DataCite
 
Title CCDC 1022741: Experimental Crystal Structure Determination 
Description Related Article: Sophie L. Benjamin, Yao-Pang Chang, Chitra Gurnani, Andrew L. Hector, Michelle Huggon, William Levason, Gillian Reid|2014|Dalton Trans.|43|16640|doi:10.1039/C4DT02694B 
Type Of Material Database/Collection of data 
Year Produced 2014 
Provided To Others? Yes  
URL http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/cc13b7nb&sid=DataCite
 
Description Deregallera 
Organisation Deregallera Ltd
Country United Kingdom 
Sector Private 
PI Contribution Contribution to a CASE PhD studentship to work on other thermoelectric materials
Collaborator Contribution Discussions, consultancy, attendance at workshops and meetings
Impact PhD studentship
Start Year 2017
 
Description CVD of thermoelectric materials 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Sparked discussion re the scope of CVD for high quality thermoelectric materials deposition and substrate selectivity in relation to thermoelectric microgenerators. Conference also attended by commercial companies developing products in this field.

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Year(s) Of Engagement Activity 2014
 
Description Gaussian Training Workshop 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Gained knowledge of electronic structure calculations

stimulated thinking towards independent career development
Year(s) Of Engagement Activity 2014
 
Description Single Source Reagents for CVD of Thermoelectric Materials 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Talk led to discussions with academics and company representatives

Further details and patent information shared with companies
Year(s) Of Engagement Activity
 
Description UK Thermoelectrics Network Meeting 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Invited talk at the EPSRC Thermoelectric Meeting, Manchester, February 2017
Year(s) Of Engagement Activity 2017
 
Description school visit (Winchester) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact activities stimulated enthusiastic discussion and engagement from pupils in STEM and Chemistry in particular

invited back
Year(s) Of Engagement Activity 2013