@inproceedings{8772666,
  abstract     = {{Cd-based quantum dots (QDs) have long been the standard in terms of stability, tunability and 
quantum efficiency (QE). In recent years, many efforts have been made to eliminate the use 
of toxic Cd and transition to more environmentally friendly InP. The use of QDs in next 
generation (organic) lighting applications, display technologies and photovoltaics requires a 
barrier layer, shielding the QDs from the environment, i.e., oxygen, moisture and temperature
[1]. In this work, we obtain high QE InP/ZnSe/ZnS core/shell/shell QDs and evaluate the barrier 
properties of a protective Al2O3 layer grown by atomic layer deposition (ALD). ALD is a vaporphase deposition technique, based on self-limiting, sequential surface reactions, unparalleled 
in thin film uniformity, conformality and thickness control. 
 A home-built photoluminescence (PL) setup is used to monitor the emission from the 
InP/ZnSe/ZnS QDs under various conditions [2]. The thermal stability, photostability and 
sensitivity of the InP/ZnSe/ZnS QDs toward water vapor and oxygen prior to ALD coating is 
treated in detail. Reversible degradation of the QD PL was observed when heating the QDs in 
vacuum, in contrast to the degradation in air. Combination of water vapor and oxygen with UV 
had a significant effect on the QD PL, with surface oxidation through oxygen exposure being 
the main degradation pathway.
 Furthermore, the effect of individual precursor, reactant and plasma exposures as well as
the full ALD process on the QD PL was investigated. The QD PL significantly decreased during 
the initial cycles of the Al2O3 ALD process. Previously, Al2O3 coating of blank polymer thin films 
was carried out indicating harmful precursor infiltration can be reduced when performing lowtemperature ALD, suitable for QD encapsulation [3]. Polymer embedding of the QDs, using 
poly(lauryl methacrylate) (PLMA) and Kraton, resulted in more stable QD thin films which retain 
most of their PL after 250 cycles of Al2O3 ALD. Different QD-polymer composite structures 
were studied, including planar thin films, spherical beads and multi-layered pockets. The
stability of the ALD coated QD-polymer composites was evaluated in a climate chamber at 
75°C/75%RH by measuring the PL at regular intervals. All samples showed an improved 
stability as a result of the Al2O3 ALD barrier layer, indicating ALD grown barrier layers can be 
used to protect QD thin films to achieve long-lasting devices with stable performance.}},
  author       = {{Petit, Robin and Van Avermaet, Hannes and Babkin, Iurii and Ozdemir, Resul and Clasen, Christian and Hens, Zeger and Detavernier, Christophe and Smet, Philippe}},
  booktitle    = {{ICOOPMA-EuroDIM 2022, Abstracts}},
  language     = {{eng}},
  location     = {{Ghent, Belgium}},
  pages        = {{1}},
  title        = {{An in situ photoluminescence study of atomic layer deposition on polymer embedded InP-based quantum dots}},
  year         = {{2022}},
}