Optical Signatures of Transiently Disordered Semiconductor Nanocrystals

Matthew S. Kirschner, Benjamin T. Diroll, Alexandra Brumberg, Ariel A. Leonard, Daniel C. Hannah, Lin X. Chen, Richard D Schaller

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The optoelectronic properties of semiconductor nanocrystals (NCs) have led to efforts to integrate them as the active material in light-emitting diodes, solid-state lighting, and lasers. Understanding related high carrier injection conditions is therefore critical as resultant thermal effects can impact optical properties. The physical integrity of NCs is indeed questionable as recent transient X-ray diffraction studies have suggested that nanoscopic particles reversibly lose crystalline order, or melt, under high fluence photoexcitation. Informed by such studies, here, we examine CdSe NCs under elevated fluences to determine the impact of lattice disordering on optical properties. To this end, we implement intensity-dependent transient absorption using both one- and two-pump methods where the latter effectively subtracts out the NC optical signatures associated with lower fluence photoexcitation, especially band-edge features. At elevated fluences, we observe a long-lived induced absorption at a lower energy than the crystalline-NC bandgap across a wide range of sizes that follows power-dependent trends and kinetics consistent with the prior transient X-ray measurements. NC photoluminescence studies provide further evidence that melting influences optical properties. These methods of characterizing bandgap narrowing caused by lattice disordering could facilitate routes to improved optical amplification and band-edge emission at high excitation density.

Original languageEnglish
JournalACS Nano
DOIs
Publication statusAccepted/In press - Jan 1 2018

Fingerprint

Nanocrystals
nanocrystals
signatures
Semiconductor materials
fluence
Optical properties
Photoexcitation
photoexcitation
optical properties
Energy gap
Pumps
pumps
Crystalline materials
carrier injection
Optoelectronic devices
illuminating
Thermal effects
integrity
Light emitting diodes
Amplification

Keywords

  • cadmium selenide
  • multiexciton
  • nanocrystals
  • thermal
  • time-resolved spectroscopy

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

Kirschner, M. S., Diroll, B. T., Brumberg, A., Leonard, A. A., Hannah, D. C., Chen, L. X., & Schaller, R. D. (Accepted/In press). Optical Signatures of Transiently Disordered Semiconductor Nanocrystals. ACS Nano. https://doi.org/10.1021/acsnano.8b04435

Optical Signatures of Transiently Disordered Semiconductor Nanocrystals. / Kirschner, Matthew S.; Diroll, Benjamin T.; Brumberg, Alexandra; Leonard, Ariel A.; Hannah, Daniel C.; Chen, Lin X.; Schaller, Richard D.

In: ACS Nano, 01.01.2018.

Research output: Contribution to journalArticle

Kirschner MS, Diroll BT, Brumberg A, Leonard AA, Hannah DC, Chen LX et al. Optical Signatures of Transiently Disordered Semiconductor Nanocrystals. ACS Nano. 2018 Jan 1. https://doi.org/10.1021/acsnano.8b04435
Kirschner, Matthew S. ; Diroll, Benjamin T. ; Brumberg, Alexandra ; Leonard, Ariel A. ; Hannah, Daniel C. ; Chen, Lin X. ; Schaller, Richard D. / Optical Signatures of Transiently Disordered Semiconductor Nanocrystals. In: ACS Nano. 2018.
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