The stability of colloidal PbS quantum dot (QD) films deposited on various substrates including glass and GaAs was
studied. Over a period of months, the QD film sample was re-tested after being left unprotected in air under ambient
conditions. Despite exposure to 532 nm laser excitation and cooling to cryogenic temperatures, the initial
photoluminescence (PL) remained stable between tests. We also retested a set of samples that had remained under
ambient conditions for over 2 years. To track potential changes to the QDs over time, X-ray photoelectron
spectroscopy (XPS), transmission electron microscopy (TEM), powder X-ray diffraction (XRD), optical microscopy,
UV-Vis-NIR spectrophotometry and atomic force microscopy (AFM) were employed. Evidence points towards
oxidation enforced shrinking of the active QD volume causing a blue shift of the absorption and photoluminescence.
The presented studies are important for reliability expectations of light emitters based on PbS QDs.
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Joanna S. Wang ; Elizabeth H. Steenbergen ; Howard E. Smith ; Lawrence Grazulis ; Jeremy A. Massengale, et al.
Stability studies of lead sulfide colloidal quantum dot films on glass and GaAs substrates
", Proc. SPIE 8634, Quantum Dots and Nanostructures: Synthesis, Characterization, and Modeling X, 86340T (March 29, 2013); doi:10.1117/12.2002499; http://dx.doi.org/10.1117/12.2002499