There is interest in the study of colloidal quantum dots (CQDs) for solar cells because of their tunable band gap. This experiment examined the kinetic decay of PbS CQDs capped with a series of ligands with a thiol group on the end of an alkane chain of varying length. Thin films were prepared by drop casting and analyzed with time resolved-infrared (TR-IR) spectroscopy experiments, which measured the concentration of electrical charges by exciting trapped electrons into delocalized states. The time scale of the kinetic decay is related to the charge recombination and is determined by the depth of the charge trap. Deeper traps are related to slower recombination and are thus detrimental to solar cells. This study observed a fast decay with 1,6-hexanedithiol (HDT). A possible explanation is that the confirmation HDT allows it to bend and interact with the surface of the CQD as a bidentate ligand.

Trapped charge dynamics depending on the length of ligands binding to the surface of solid state quantum dots

243rd National Meeting (2012)

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