Inorganically Connecting Colloidal Nanocrystals Significantly Improves Mechanical Properties

Zhongyong Wang, Soundarya Srinivasan, Rui Dai, Ashish Rana, Qiong Nian, Kiran Solanki, Robert Y. Wang

Research output: Contribution to journalArticlepeer-review

Abstract

Understanding and characterizing the mechanical behavior of colloidal nanocrystal (NC) assemblies are important for developing nanocrystalline materials with exceptional mechanical properties for robust electronic, thermoelectric, photovoltaic, and optoelectronic devices. However, the limited ranges of Young's modulus, hardness, and fracture toughness (≲1-10 GPa, ≲50-500 MPa, and ≲10-50 kPa m1/2, respectively) in as-synthesized NC assemblies present challenges for their mechanical stability and therefore their practical applications. In this work, we demonstrate using a combination of nanoindentation measurements and coarse-grained modeling that the mechanical response of assemblies of as-synthesized NCs is governed by the van der Waals interactions of the organic surface ligands. More importantly, we report tremendous ∼60× enhancements in Young's modulus and hardness and an ∼80× enhancement in fracture toughness of CdSe NC assemblies through a simple inorganic Sn2S64- ligand exchange process. Moreover, our observation of softening in nanocrystalline materials with decreasing CdSe NC diameter is consistent with atomistic simulations.

Original languageEnglish (US)
Pages (from-to)4916-4922
Number of pages7
JournalNano Letters
Volume23
Issue number11
DOIs
StatePublished - Jun 14 2023

Keywords

  • atomistic molecular dynamics
  • coarse-grained model
  • inorganic ligands
  • mechanical properties
  • nanocrystal

ASJC Scopus subject areas

  • Bioengineering
  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics
  • Mechanical Engineering

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