2021-10-25

Scientists use inkjet printers to make flexible LEDs with strong scalability

By yqqlm yqqlm

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2d9955d02f91a73 - Scientists use inkjet printers to make flexible LEDs with strong scalability

the study was published in the journal advanced materials this month

OLEDs made of organic small molecules or polymers are cheap and flexible. “You can bend or stretch them – but they have relatively low performance and short life. Inorganic LEDs, such as microleds, have high performance, super bright, very reliable, but inflexible and very expensive.”

“what we do is an organic-inorganic compound,” he said. “It has the best characteristics of these two worlds.” they used a special type of crystalline material called organometallic halide perovskite – despite a new turn. The traditional way to create a thin layer of perovskite is to drop it on a flat, rotating substrate, just like a rotating art toy. This process is called rotating coating. As the substrate rotates, the liquid diffuses and eventually covers it with a thin layer. There, it can be recycled and made into perovskite LEDs, or peleds

however, like the art of rotation, a lot of materials are wasted in this process – when the substrate rotates at the speed of thousands of revolutions, some dripping perovskite splashes and flies away, and does not stick to the substrate

Wang Chuan said: “because it appears in liquid form, we imagine that we can use an inkjet printer to replace the rotating coating.”

inkjet manufacturing saves materials because peroxide can only be deposited where needed, just like the accuracy of printing letters and numbers on a piece of paper; No splash, reduce waste. This process is also much faster, and the production time is shortened from more than 5 hours to less than 25 minutes

another advantage of using inkjet printing may reshape the future of electronic products: perovskite can be printed on a variety of unconventional substrates, including materials that are unstable during rotation, such as rubber. Wang Chuan said: “Imagine a device that starts out as the size of a mobile phone, but can stretch to the size of a tablet

however, in order to make the display flexible, printing hard LEDs on rubber does not work. The LED itself needs to be flexible. Perovskite is not

researchers can solve this problem by embedding inorganic perovskite crystals into an organic polymer matrix made of polymer adhesives. This makes the peroxide and Peled itself elastic and stretchable. This process is not entirely simple. The researchers agree that the biggest obstacle is to ensure that the materials of different layers do not mix

because all parts of Peled are made of liquid — perovskite layer, two electrodes and a buffer layer — a major problem is to keep all layers from mixing

The structure of

LED is similar to sandwich, with at least one emission layer, one anode layer and one cathode layer. Sometimes other layers may be used. Researchers must keep the titanite layer from mixing with any other layer, just like smearing a new ink with a fluorescent pen. They need to find a suitable polymer, a polymer that can be inserted between peroxide and other layers, so as to protect it without too much interference with the performance of Peled

“we found the best material and thickness to balance the performance and protection of the equipment,” the researchers said. After that, he continued to print the first elastic peleds

the Technology Management Office of the university is applying for a patent for the technology and manufacturing method. These peleds may just be the first step in the electronic revolution. They can be used to make wearable devices, or even intelligent wearable devices, such as pulse oximeters that measure blood oxygen. Researchers believe that the most exciting thing is that being able to print elastic Peled cheaply and quickly may bring new technologies that have not yet been dreamed of