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Perovskite sensors for better colour reproduction and fewer image artefacts with less light
Researchers for the ETH in Zurich are proposing a novel solution which allows them to utilize every photon of light for colour recognition – front the ETH website:
The basis for their innovative image sensor is lead halide perovskite. This crystalline material is also a semiconductor. In contrast to silicon, however, it is particularly easy to process – and its physical properties vary with its exact chemical composition. This is precisely what the researchers are taking advantage of in the manufacture of perovskite image sensors.
If the perovskite contains slightly more iodine ions, it absorbs red light. For green, the researchers add more bromine, for blue more chlorine – without any need for filters. The perovskite pixel layers remain transparent for the other wavelengths, allowing them to pass through. This means that the pixels for red, green and blue can be stacked on top of each other in the image sensor, unlike with silicon image sensors, where the pixels are arranged side-by-side.
Thanks to this arrangement, perovskite-based image sensors can, in theory, capture three times as much light as conventional image sensors of the same surface area while also providing three times higher spatial resolution. Researchers from Kovalenko’s team were able to demonstrate this a few years ago, initially with individual oversized pixels made of millimeter-large single crystals.
Now, for the first time, they have built two fully functional thin-film perovskite image sensors. “We are developing the technology further from a rough proof of principle to a dimension where it could actually be used,” says Kovalenko. A normal course of development for electronic components: “The first transistor consisted of a large piece of germanium with a couple of connections. Today, 60 years later, transistors measure just a few nanometers.”
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