How Pixels Glow
Have you ever wondered how the pixels of your new television actually shine? In the latest displays, each pixel is built from nanoparticles that shine in red, green, and blue, which are the fundamental colors that create every image. At the University of Antwerp, we are investigating the structure of those nanoparticles at an atomic level to improve their performance.
The Rabbit Hole: Entering the Nanoscale World
When Alice tumbled down the rabbit hole in Alice in Wonderland, she entered a world where everything behaved in strange and marvelous ways. As she shrank smaller and smaller, the world around her transformed and the light seems to shimmer in new colors. She was still in the same place, yet everything behaved in ways she had never seen before.
“When materials become as small as a few billionths of a meter, their properties can shift dramatically.” – Nadine Schrenker
This is what it’s like to explore the nanoscale. When materials become as small as a few billionths of a meter, their properties can shift dramatically. Gold, for instance, no longer looks metallic yellow, but instead glows red or purple. The same substance reveals new properties when it is simply made smaller.
Nano-Ink for Green Energy
The usefulness of nanomaterials goes beyond digital displays and also extends to other applications, including green energy and catalysts. Quantum dots are tiny semiconductor particles whose size determine their color and behavior. These dots have such potential that the scientists who pioneered their discovery were awarded the Nobel Prize in Chemistry in 2023.
Perovskite nanocrystals belong to the same fascinating family of semiconductors. By carefully tuning their size and composition, scientists can make them emit any color across the visible spectrum.
“Because perovskites are synthesized in a solution, they can be used like an ink: printed or sprayed onto lightweight, flexible surfaces.” – Nadine Schrenker
Over the past fifteen years, perovskites have also revolutionized solar energy research. Solar cells made with these materials have reached over 20% efficiency — rivaling traditional silicon cells, but at a much lower cost. And because perovskites are synthesized in a solution, they can be used like an ink: printed or sprayed onto lightweight, flexible surfaces, either as solar cells or light-emitting diodes, depending on the application. But to realize the full potential of these materials, we need to first uncover their basic structure.
Revealing the Building Blocks of Nanomaterials
To truly understand and improve these materials, we have to look at their building blocks, which are atoms. Using electron microscopy, we can zoom in to see the specific arrangement of these atoms, which determines the optical properties and stability of nanomaterials.
However, common electron microscopy techniques are sensitive to detecting either light or heavy elements — not both simultaneously. This is a problem when studying specific materials like perovskite nanocrystals, because they often contain both light elements (like organic cations) and heavy elements (like lead cations).
“Our method reduces the electron beam current, avoiding damage to the precious perovskite crystals we’re studying.” – Nadine Schrenker
To overcome this limitation, we’ve developed a novel imaging method at the University of Antwerp. Using machine learning for the image reconstruction, our method reveals light and heavy elements at the same time. Since we also use new direct electron detectors which can detect even single electrons that interacted with the sample, this approach is also more sensitive than previous scintillator-based detectors. Another advantage is that our method reduces the electron beam current, avoiding damage to the precious perovskite crystals we’re studying — a common issue with other electron microscopy techniques.
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Using this approach, we can now observe tiny shifts in light atoms from their expected positions. These small movements are key indicators of how stable a material is over time. In the future, we want to track how these structures change under different conditions, like humidity, to learn how we can prevent degradation that limits a device’s lifespan.
Bright Discoveries Ahead
Just like Alice’s journey through Wonderland, exploring the nanoscale reveals that the smallest worlds can hold the most extraordinary surprises. By peering deep into the atomic structure of these tiny perovskite crystals, we are opening the door to brighter, more efficient, and more sustainable technologies — one atom at a time.
Written by Nadine Schrenker for the SciMingo Popular Science Writing Course.
