UT-BORN-PT – Unconventional Thermoelectrics Based on Self-Organized Binary Nanocrystal Superlatices


Alongside alternative clean energy sources, energy recovery and conversion will play an important role in addressing future technologies, especially for autonomous devices. Thermoelectric devices convert temperature gradients into electric power and vice versa have been actively investigated to enhance existing technologies for heat/power recovery and conversion.

They are reliable, non-polluting, require minimal maintenance, and can be operated over a wide range of temperatures. If it were not for its currently low efficiency, thermoelectric energy conversion could revolutionary replace thermomechanical conversion in many applications. The performance of thermoelectric materials is expressed by the dimensionless figure-of-merit, zT, which is about 1.2 for materials currently used in thermoelectric devices. For wide adoption, the zT needs to reach a value of three, a goal that has been pursued for over 50 years. Recent record zT values approaching two are driven in part by nanocrystals self-precipitated in bulk, even though control and understanding of nanocrystal formation remain elusive in these systems.

UT-BORN-PT aimed at significantly increasing zT values of thermoelectrics by nanostructuring thermoelectric materials into nanocrystal solids that can offer high electrical conductivity while dramatically lowering the thermal conductivity. The project proposed an approach to creating completely new high-zT thermoelectrics via the bottom-up assembly of thermoelectric nanocrystals.

Thermoelectric generators (TEGs) interconverts heat and electrical energy, and are energy recovery and conversion devices with enormous potential to harvest the dissipated heat from power plants, automotive engines, housing heating systems, and even electronic devices for micro-power generation applications.

The synthesized BNSLs based thermoelectric materials have led to the development of next-generation of thermoelectrics and concurrently will provide a fundamental breakthrough for simple, scalable and low-cost processing of high-performance TEGs.


Title Unconventional Thermoelectrics Based on Self-Organized Binary Nanocrystal Superlatices
Reference UTAP-EXPL/CTE/0050/2017
Scientific Area Nanotechnologies
Funding € 98 881,00 plus matched funding at UT Austin
Leading Institution Laboratório Ibérico Internacional de Nanotecnologias (INL)
Participating Institutions The University of Austin at Texas (UT Austin)
Universidade do Minho (UM)
Duration 18 months
Begin date November 1, 2018
End date April 30, 2020
Keywords Self-assembly, Nanocrystal superlatices, Nanostructured thermoelectrics, Transport properties

Main Highlights

  • Scalable thermochemical alloying route for synthesizing chalcogenides nanocrystals;
  • Cumulative temperature dependence approach for estimation of realistic thermoelectric performance;
  • Bulk nanostructured n-type alloys with ZTavg≈0.7 with an estimated thermoelectric conversion efficiency of approx. 5-6%;
  • Bulk p-type nanocomposite with ZTavg≈1.2 for low-temperature thermoelectric application;
  • Ligand engineered phase-pure 150 nm thick films of oleate-capped PbTe NCs with reduced thermal conductivity.


  • 5 Published papers in peer-reviewed Journals and Conferences;
  • 2 Undergraduate students involved in research work;
  • 1 Mobility exchange supported;
  • 1 New funding application deriving from UT-BORN-PT (H2020).

Papers and Communications

  • Piotrowski, Marek, et al. Probing of thermal transport in 50 nm thick PbTe nanocrystal films by time-domain thermoreflectance. The Journal of Physical Chemistry C 122.48 (2018): 27127-27134
  • Piotrowski, Marek, et al. Template-directed self-organization of colloidal PbTe nanocrystals into pillars, conformal coatings, and self-supported membranes. Nanoscale Advances 1.8 (2019): 3049-3055
  • Chauhan, Nagendra S., et al. Spinodal decomposition in (Ti, Zr) CoSb half-Heusler: A nanostructuring route toward high- efficiency thermoelectric materials. Journal of Applied Physics 126.12 (2019): 125110
  • Chauhan, Nagendra S., et al. Defect Engineering for Enhancement of Thermoelectric Performance of (Zr, Hf) NiSn-Based n-type Half-Heusler Alloys. The Journal of Physical Chemistry C 124.16 (2020): 8584-8593
  • Upadhyay, Naval Kishor, et al. Facile bulk synthesis of high-performance B-Zn4Sb3 for thermoelectric applications. Materials Letters 265 (2020): 127428



Unconventional Thermoelectrics Based on Self-Organized Binary Nanocrystal Superlatices

Project Team

Yury Kolen’ko

Principal Investigator in Portugal

Brian Korgel

Principal Investigator in Austin