The generation and transfer of triplet excitons across the molecular-semiconductor interface represents an important technological breakthrough featuring numerous fundamental scientific questions. This contribution demonstrates curious delayed formation of TIPS-pentacene molecular triplet excitons bound on the surface of PbS nanocrystals mediated through the initial production of a proposed charge transfer intermediate following selective excitation of the PbS quantum dots. Ultrafast UV-vis and near-IR transient absorption spectroscopy was used to track the dynamics of the initial PbS exciton quenching as well as time scale of the formation of molecular triplet excited states that persisted for 10 μs on the PbS surface, enabling subsequent energy and electron transfer reactivity. These results provide the pivotal proof-of-concept that PbS nanocrystals absorbing near-IR radiation can ultimately generate molecular triplets on their surfaces through processes distinct from direct Dexter triplet energy transfer. More broadly, this work establishes that small metal chalcogenide semiconductor nanocrystals interfaced with molecular chromophores exhibit behavior reminiscent of supramolecular chemical systems, a potentially impactful concept for nanoscience.
|Number of pages||6|
|Journal||Journal of Physical Chemistry Letters|
|State||Published - Apr 6 2017|
Bibliographical noteFunding Information:
This work was supported by the Ultrafast Initiative of the US Department of Energy, Office of Science, Office of Basic Energy Sciences, through Argonne National Laboratory under Contract No. DE-AC02-06CH11357, the Air Force Office of Scientific Research (FA9550-13-1-0106), and the National Science Foundation (CMMI-1255494). S.G. is a Chemistry Graduate Scholars Research Assistant at NC State University. We thank Prof. Kenan Gundogdu at NC State for an insightful discussion regarding long-range dipole interactions between nanoparticles and surface-bound molecules.
ASJC Scopus subject areas
- Materials Science (all)
- Physical and Theoretical Chemistry