Heat Transfer at Hybrid Interfaces: Interfacial Ligand-to-Nanocrystal Heating Monitored with Infrared Pump, Electronic Probe Spectroscopy

Benjamin T. Diroll, Peijun Guo, Richard D. Schaller

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The transfer of thermal energy from the ligand passivating layer to the inorganic core of colloidal nanocrystals is observed using infrared-pump, electronic-probe (IPEP) spectroscopy. Inorganic nanocrystals are excellent model systems for organic-inorganic hybrid interfaces as they have much larger surface-to-volume ratios than bulk solids, which facilitate spectroscopic measurements of weak signals. Such interfaces between disparate materials are challenging to probe by traditional methods. Here, resonant excitation of the hydrocarbon ligand vibrational absorptions results in a transient red-shift of the CdSe nanocrystal excitonic features consistent with heating, as demonstrated by steady-state absorption measurements, which provide a calibration of the pump-induced temperature rise. The time constant associated with heating ranges from 10 to 30 ps depending on the sample morphology, static temperature, input fluence, and environment, all of which are studied in this work. Heat transfer speeds up and the magnitude of nanocrystal heating decreases at higher temperatures. Unlike chemical modulation of electrical conductivity, ligand exchange for several common organic ligands does not dramatically change the interfacial conductivity of the nanocrystal-ligand interface. However, changes in the medium (e.g., solvent) do change the rate of heat outcoupling from the nanocrystal-ligand complex. Although applied here to nanocrystals to measure interfacial heat transfer, IPEP spectroscopy is readily applicable for any heterogeneous system in which one component has spectrally isolated molecular vibrations or lattice phonons.

Original languageEnglish
Pages (from-to)7863-7869
Number of pages7
JournalNano letters
Volume18
Issue number12
DOIs
Publication statusPublished - Dec 12 2018

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Keywords

  • Thermal transport
  • heating
  • infrared
  • ligand
  • nanocrystal

ASJC Scopus subject areas

  • Bioengineering
  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanical Engineering

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