Sample of green luminescent perovskite quantum dots excited by blue laser

Date of issue:

2019-01-01

According to previous research, quantum dots emit light after being excited at room temperature for about 20 billionths of a second (Nanoseconds); while cesium lead halide quantum dots are also excited at room temperature for about one billionth of a billion It will glow in seconds. In contrast, lead cesium halide quantum dots react fairly quickly.


David Norris, a professor of materials engineering, explained that the use of photon (Photon) to excite nanocrystals can cause electrons to leave the position of the original lattice and generate holes; while the electron-hole pair is in an excited state. -The hole will only glow when it returns to the ground state.


However, most of the quantum dot materials will be in the Dark State, and will not be able to absorb the photon state, so that the electron-hole pair cannot be restored to the ground state, so the light emission time is limited and delayed. The cesium lead halide quantum dots do not often have Dark State, so they can emit light immediately. This is why lead cesium halide quantum dots react fast and the light after being excited is also brighter.


Sample of green luminescent perovskite quantum dots excited by blue laser


Cheaper and safer LEDs


Researchers at Oregon State University used a 'super acid' that is much stronger than car battery acid to improve the performance of 'quantum dots' made of copper indium disulfide. This research is expected to produce cheaper and safer LEDs.


Quantum dots have been used in optics and electronics for some time. However, due to the toxicity of lead and cadmium, their manufacturing cost is very high, and it is also unsafe for some potential applications (such as biomedical imaging).


Greg Herman, a professor of chemical engineering at Oregon State University, said, 'Quantum dots can be applied to a variety of products and technologies, but for mass consumer use, perhaps the most important thing is to improve LED lighting.' Dot luminescent nanocrystal TV. '


This latest study was published in the journal Materials Letters. In the study, the researchers developed a treatment method of super strong acids, which can increase the photoluminescence of non-toxic, non-heavy metal quantum dots to a comparable level of cadmium selenide.


Greg Herman also said: 'The light emission of this super acid-treated quantum dot is much better', 'There are still some problems to be solved, but we have proved that it can improve the life of quantum dots and improve quantum efficiency. And Because these quantum dots are non-toxic, they also have potential for biomedical applications. '


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