Difference in hot carrier cooling rate between Langmuir-Blodgett and drop cast PbS QD films due to strong electron-phonon coupling

Wenkai Cao, Lin Yuan, Rob Patterson, Xiaoming Wen, Patrick C. Tapping, Tak Kee, Binesh Puthen Veetil, Pengfei Zhang, Zewen Zhang, Qiuyang Zhang, Peter Reece, Stephen Bremner, Santosh Shrestha, Gavin Conibeer, Shujuan Huang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)

Abstract

The carrier dynamics of lead sulphide quantum dot (PbS QD) drop cast films and closely packed ordered Langmuir-Blodgett films are studied with ultra-fast femtosecond transient absorption spectroscopy. The photo-induced carrier temperature is extracted from transient absorption spectra and monitored as a function of time delay. The cooling dynamics of carriers in PbS QDs suggest a reduction of the carrier energy loss rate at longer time delays through the retardation of the longitudinal optical (LO) phonon decay due to partial heating of acoustic phonon modes. A slowed hot carrier cooling time up to 116 ps is observed in the drop cast film. A faster cooling rate was also observed in the highly compact Langmuir-Blodgett film due to the enhanced carrier-LO phonon coupling strength arising from the Coulombic interaction in neighboring QDs, which is verified by temperature dependent steady state PL measurements.

Original languageEnglish
Pages (from-to)17133-17142
Number of pages10
JournalNanoscale
Volume9
Issue number43
DOIs
Publication statusPublished - 21 Nov 2017
Externally publishedYes

Fingerprint Dive into the research topics of 'Difference in hot carrier cooling rate between Langmuir-Blodgett and drop cast PbS QD films due to strong electron-phonon coupling'. Together they form a unique fingerprint.

Cite this