TY - JOUR
T1 - Ultrafast electron trapping at the surface of semiconductor nanocrystals
T2 - Excitonic and biexcitonic processes
AU - Saari, Jonathan I.
AU - Dias, Eva A.
AU - Reifsnyder, Danielle
AU - Krause, Michael M.
AU - Walsh, Brenna R.
AU - Murray, Christopher B.
AU - Kambhampati, Patanjali
PY - 2013/4/25
Y1 - 2013/4/25
N2 - Aging of semiconductor nanocrystals (NCs) is well-known to attenuate the spontaneous photoluminescence from the band edge excitonic state by introduction of nonradiative trap states formed at the NC surface. In order to explore charge carrier dynamics dictated by the surface of the NC, femtosecond pump/probe spectroscopic experiments are performed on freshly synthesized and aged CdTe NCs. These experiments reveal fast electron trapping for aged CdTe NCs from the single excitonic state (X). Pump fluence dependence with excitonic state-resolved optical pumping enables directly populating the biexcitonic state (XX), which produces further accelerated electron trapping rates. This increase in electron trapping rate triggers coherent acoustic phonons by virtue of the ultrafast impulsive time scale of the surface trapping process. The observed trapping rates are discussed in terms of electron transfer theory.
AB - Aging of semiconductor nanocrystals (NCs) is well-known to attenuate the spontaneous photoluminescence from the band edge excitonic state by introduction of nonradiative trap states formed at the NC surface. In order to explore charge carrier dynamics dictated by the surface of the NC, femtosecond pump/probe spectroscopic experiments are performed on freshly synthesized and aged CdTe NCs. These experiments reveal fast electron trapping for aged CdTe NCs from the single excitonic state (X). Pump fluence dependence with excitonic state-resolved optical pumping enables directly populating the biexcitonic state (XX), which produces further accelerated electron trapping rates. This increase in electron trapping rate triggers coherent acoustic phonons by virtue of the ultrafast impulsive time scale of the surface trapping process. The observed trapping rates are discussed in terms of electron transfer theory.
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U2 - 10.1021/jp307668g
DO - 10.1021/jp307668g
M3 - Article
AN - SCOPUS:84876762991
SN - 1520-6106
VL - 117
SP - 4412
EP - 4421
JO - Journal of Physical Chemistry B
JF - Journal of Physical Chemistry B
IS - 16
ER -