Difference in hot carrier cooling rate between Langmuir-Blodgett and drop cast PbS QD films due to strong electron-phonon coupling
Date
2017
Authors
Cao, W.
Yuan, L.
Patterson, R.
Wen, X.
Tapping, P.
Kee, T.
Veetil, B.
Zhang, P.
Zhang, Z.
Zhang, Q.
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Advisors
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Volume Title
Type:
Journal article
Citation
Nanoscale, 2017; 9(43):17133-17142
Statement of Responsibility
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 and Shujuan Huang
Conference Name
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.
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Published on 29 September 2017
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This journal is © The Royal Society of Chemistry 2017