Electron microscopy images of perovskite quantum dots embedded in the protective alumina matrix, and a photograph of the same film stable in water. Credit: © R. Buonsanti/EPFL
EPFL scientists have built a new type of inorganic nanocomposite that makes perovskite quantum dot exceptionally stable against air exposure, sunlight, heat, and water. Quantum dots are nanometer-size, semiconducting materials whose tiny size gives them unique optical properties. Much effort has been put in building quantum dots from perovskites, which already show much promise for solar panels, LEDs and laser technologies.
The new approach to stabilize the perovskite quantum dots was developed in the lab of Raffaella Buonsanti at EPFL Valais Wallis. The innovation lies in “atomic layer deposition” (ALD), commonly used to fabricate ultra-thin films with high uniformity in their structure. The idea was to use ALD to encapsulate the perovskite quantum dots with an amorphous alumina matrix, which acts as a gas and ion diffusion barrier thus making the quantum dots more robust against air, light, heat, and moisture.
The team used an array of characterization techniques to monitor the nucleation and growth process of the alumina matrix on the quantum dot surface. The process showed that the interaction between the ALD precursor and the dot surface is crucial in order to uniformly coat the dots while preserving their optoelectronic properties. “By addressing the stability challenge of perovskite quantum dots, this work is expected to greatly impact the field by enabling fundamental optoelectronic studies, which require the samples to be stable during the measurements, in addition to increase the durability of devices based on this new class of quantum dots,” say the authors. https://actu.epfl.ch/news/new-method-improves-stability-of-perovskite-quantu/
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