Low-Temperature-Processed Colloidal Quantum Dots as Building Blocks for Thermoelectrics

Mohamad I. Nugraha, Hyunho Kim, Bin Sun, Md Azimul Haque, Francisco Pelayo Garcia de Arquer, Diego Rosas Villalva, Abdulrahman El-Labban, Edward H. Sargent, Husam N. Alshareef, Derya Baran*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Colloidal quantum dots (CQDs) are demonstrated to be promising materials to realize high-performance thermoelectrics owing to their low thermal conductivity. The most studied CQD films, however, are using long ligands that require high processing and operation temperature (>400 °C) to achieve optimum thermoelectric performance. Here the thermoelectric properties of CQD films cross-linked using short ligands that allow strong inter-QD coupling are reported. Using the ligands, p-type thermoelectric solids are demonstrated with a high Seebeck coefficient and power factor of 400 μV K −1 and 30 µW m −1 K −2 , respectively, leading to maximum ZT of 0.02 at a lower measurement temperature (<400 K) and lower processing temperature (<300 °C). These ligands further reduce the annealing temperature to 175 °C, significantly increasing the Seebeck coefficient of the CQD films to 580 μV K −1 . This high Seebeck coefficient with a superior ZT near room temperature compared to previously reported high temperature-annealed CQD films is ascribed to the smaller grain size, which enables the retainment of quantum confinement and significantly increases the hole effective mass in the films. This study provides a pathway to approach quantum confinement for achieving a high Seebeck coefficient yet strong inter-QD coupling, which offers a step toward low-temperature-processed high-performance thermoelectric generators.

Original languageEnglish (US)
Article number1803049
JournalAdvanced Energy Materials
Volume9
Issue number13
DOIs
StatePublished - Apr 4 2019

Keywords

  • colloidal quantum dots
  • power factor
  • quantum dot thermoelectrics
  • solution processable materials
  • thermoelectrics

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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