(Left and center) Electron microscopy images of perovskite quantum dots embedded in the protective alumina matrix; (right) photo of the same film stable in water. Images: R. Buonsanti/EPFL.Scientists at the Ecole Polytechnique Federale de Lausanne (EPFL) in Switzerland have built a new type of inorganic nanocomposite that can protect perovskite quantum dots against air, sunlight, heat and water.
Quantum dots are nanometer-size, semiconducting materials whose tiny size gives them unique optical properties. Much effort has been put into building quantum dots from perovskites, which have already shown much promise for use in solar panels, LEDs and laser technologies.
The fundamental optoelectronic properties of perovskite quantum dots are unique and of great interest among the scientific community. However, they have huge issues with stability when exposed to air, heat, light or water. Now, however, EPFL scientists have succeeded in building perovskite quantum dot films that can overcome these weaknesses. Their work is reported in a paper in Angewandte Chemie.
This new approach to stabilizing perovskite quantum dots was developed in the lab of Raffaella Buonsanti at EPFL. It takes advantage of a technique called ‘atomic layer deposition’ (ALD), which is commonly used to fabricate ultra-thin films with a highly uniform structure. Buonsanti and his colleagues used ALD to encapsulate the perovskite quantum dots within an amorphous alumina matrix. This matrix acts as a gas and ion diffusion barrier that protects the sensitive quantum dots from 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. These showed that the interaction between the ALD precursor and the dot surface is crucial for uniformly coating 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.
This story is adapted from material from EPFL, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.