Scientists at the École Polytechnique Fédérale de Lausanne (EPFL), Switzerland, have built a new type of inorganic nanocomposite that makes perovskite quantum dots stable against air exposure, sunlight, heat and water.
Quantum dots are nanometre-sized, semiconducting materials whose small size gives them optical properties. Using quantum dots from perovskites has already shown promise for solar panels, LEDs and laser technologies. However, perovskite quantum dots have issues with stability against air, heat, light and water.
EPFL scientists have now succeeded in building perovskite quantum dot films with a technique that helps them overcome these weaknesses.
The new approach to stabilise the perovskite quantum dots was developed in the lab of Raffaella Buonsanti at EPFL Valais Wallis. The innovation of this study, developed by Anna Loiudice and PhD student Seryio Saris, lies in a technique called atomic layer deposition (ALD), which is commonly used to fabricate ultra-thin films with high uniformity in their structure. ALD was used 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 characterisation techniques to monitor the nucleation and growth process of the alumina matrix on the quantum dot surface.
Loiudice said: “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.”
The work is published in Angewandte Chemie.