Bryan KUROPATWA

Techniques de recherche

1. Design and implication of Seebeck measurement instrument.
2. Characterization of materials’thermoelectricproperties.
3. Synthesis& design of conductivepolymers.
4. Fabrication &processing of organicthin films.
5. Solid state crystallography.

Thèmes

With an ever-increasing global demand for energy, every Watt must count. This includes the implication of new, efficient methods of harvesting and reusing energy from green sources. Since the discovery of the Seebeck Effect in 1821, thermoelectric materials have been a subject of great interest for any involved in materials science. These particular materials are capable of converting a temperature gradient into electricity. They are often semiconducting in nature and can be used as a method for cooling (Peltier effect) upon application of a current, or as power generation (Seebeck effect) when a temperature gradient is,  instead,  applied.

In order to be efficient, thermoelectric materials must allow efficient electron flow whilst blocking the parallel flow of heat – phonons. Three physical properties must therefore be considered : the Seebeck Coefficient (S), the entropy per unit charge, is regarded as the voltage change over the applied temperature gradient (S=ΔV/ΔT) ; the electrical conductivity (σ) is the material’s ability to move an electric charge ; and the thermal conductivity (κ), is the material’s ability to move phonons. When combined with the average temperature of an applied gradient, the thermoelectric figure of merit is given as zT = S²σ/κ. All parameters must therefore be optimised and measured before a potential thermoelectric material is considered promising.

Conjugated polymers are comprised of a covalently bonded carbon back bone and conjugated pi-electrons. The pi-electrons form a channel for transport that makes an otherwise insulating material behave like a metal or semiconductor. Polyacetylene is the simplest example of this type of material. Polymers have the advantage over traditional thermoelectric materials such as bismuth telluride (Bi₂Te₃) because they are light, flexible, transparent, inexpensive, and do not contain heavymetals or rare elements. As thin films or rolls, they can possibly be applied to current technology such as solar cells as well as a separate device. The correct amount of dopant, charge carrier concentration, and therefore S and σ can be chemically optimised for a better zT value. Similarly, improved processing techniques can form better films and polymers with more ordered alignments can optimise σ whilst keeping κ supressed.

Collaborations

LCPO : Laboratoire de Chimie des Polymères Organiques

AMADEus : Advanced MAterials by DEsign

NSERC : Natural Sciences and Engineering Research Council of Canada

Publications

1. Optimization of the Telluride Tl_10–x–ySn_xBi_yTe₆ for Thermoelectric Energy Conversion
   B. A. Kuropatwa, Q. Guo, A. Assoud, H. Kleinke.
   ZAACh.2014, 640, 774-780.

2. Enhancedthermoelectricproperties of variants of Tl₉SbTe₆ and Tl₉BiTe₆
   Q. Guo, M. Chan, B. A. Kuropatwa, H. Kleinke.
   Chem. Mater.2013, 25(20), 4097 – 4104.

3. Effects of Cation Site Substitutions on the Thermoelectric Performance of LayeredSnBi₂Te₄utilizing the Triel Elements Ga, In, and Tl
   B. A. Kuropatwa, A. Assoud, H. Kleinke.
   ZAACh.2013, 639, 2411 – 2420.

4. ThermoelectricProperties of Stoichiometric Compounds in the (SnTe)_x(Bi₂Te₃)_y System
   B. A. Kuropatwa, H. Kleinke.
   ZAACh.2012, 638, 2640.

5. Structures and properties of the ternary thallium chalcogenides Tl₂MQ₃ (M = Zr, Hf; Q = S, Se)
   C. R. Sankar, B. A. Kuropatwa, A. Assoud, H. Kleinke.
   Dalton Trans.2012, 41 (32), 9646 – 9650.

6. Crystal Structure and PhysicalProperties of the New One-DimensionalMetal Ba₂Cu_7–xTe₆
   B. A. Kuropatwa, A. Assoud, H. Kleinke.
   Inorg. Chem.2012, 51 (9), 5299 – 5304.

7. Bariummanganese(II) selenostannate(IV), BaMnSnSe₄
   A. Assoud, B. A. Kuropatwa, H. Kleinke.
   Acta Crystallogr.2011, E 67, i72 – i72.

8. Crystal Structure and PhysicalProperties of the New Chalcogenides Ba₃Cu_17–x(S,Te)₁₁ and Ba₃Cu_17–x(S,Te)_11.5 withTwoDifferent Cu Clusters
   B. A. Kuropatwa, A. Assoud, H. Kleinke.
   Inorg. Chem.2011, 50 (16), 7831 – 7837.

9. Phase Range and PhysicalProperties of the Thallium Tin Tellurides Tl_10–xSn_xTe₆ (x≤2.2)
   B. A. Kuropatwa, A. Assoud, H. Kleinke.
   J. AlloysCompd.2011, 509, 6768 – 6772.

1. Crystal Structure and PhysicalProperties of the New Selenide-Tellurides Ba₃Cu_17–x(Se,Te)₁₁.
   B. Kuropatwa, Y. Cui, A. Assoud, H. Kleinke.
   Chem. Mater.2009, 21(1), 88 – 93.

1. Yb(OTf)₃-Catalyzed Reactions of 5-Alkylidene Meldrum’sAcidswithPhenols: One-Pot Assembly of 3,4-Dihydrocoumarins, 4-Chromanones, Coumarins, and Chromones
   E. Fillion, A. Dumas, B. A. Kuropatwa, N. Malhotra, T. Sitler.
   J. Org. Chem. 2006, 71, 409 – 412.

Curriculum vitae

Education

Awards, Academic Achievements & Scholarships

Selected Technique Experience

Selected Services  & Memberships