Although interest in the elucidation of energy and/or electron transfer mechanisms across the interface between semiconductor nanomaterials and functional organic capping ligands has grown in intensity over the past few years, many fundamental questions remain unanswered. PbS quantum dots (QDs) are an attractive class of semiconductor nanomaterials due to their near-infrared light absorption and excellent colloidal stability in solution. Time-resolved dynamics of PbS hybrid QD-molecular systems have been independently investigated through variation of the QD size or by the use of PbS/CdS core-shell motifs. The present study takes a more comprehensive approach wherein PbS and PbS/CdS core-shell QDs are synthesized with both the PbS core diameter and the CdS shell size systematically tuned. Each QD across this library was post-synthetically modified with the same carboxylate-functionalized TIPS-pentacene derivative (TPnCOOH) as a chromophoric capping agent. The photophysical dynamics and exciton transfer processes were interrogated using a combination of static and time-resolved optical spectroscopies from ~100 fs to milliseconds. These systematic investigations have gleaned true mechanistic insights leading to an enhanced understanding of the interfacial exciton transfer processes occurring between PbS QDs and surface-anchored TPnCOOH molecules.

Triplet exciton transfer in PbS/CdS core-shell quantum dots with surface-appended chromophores

2019 Fall National Meeting

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