Colloidal quantum dots make LEDs shine bright in the infrared

phys.org | 12/4/2018 | Staff
Kaliela101 (Posted by) Level 3
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The ideal optoelectronic semiconductor material would be a strong light emitter and an efficient charge conductor to allow for electrical injection in devices. These two conditions, when met, can lead to highly efficient LEDs as well as to solar cells that approach the Shockley-Queisser limit. Until now, the materials that have come closest to meeting these conditions have been based on costly, epitaxially-grown III-V semiconductors that cannot be monolithically integrated to CMOS electronics.

The ICFO team now reports a processed nanocomposite system comprising infrared colloidal quantum dots. It meets these criteria, and at the same time, offers low cost and facile CMOS integration. Colloidal quantum dots (CQDs) are semiconductor particles or crystals as small as a few nanometers in size, which therefore have unique optical and electronic properties. They are excellent absorbers and emitters of light, and their properties change as a function of their size and shape: Smaller quantum dots emit in the blue range while larger quantum dots emit in the red.

Use - CQD - LEDs - Third-generation - Solar

The use of CQD LEDs could contribute to third-generation, solution-processed inorganic solar cells. The implementation of these nanocrystals in devices for optical sensing in the short-wave and mid-infrared have a vast number of applications, including surveillance, night vision, and environmental monitoring and spectroscopy.

In this recent study, published in Nature Nanotechnology, ICFO researchers Santanu Padhan, Francesco Di Stasio, Yu Bi, Shuchi Gupta, Sotirios Christodoulou, and Alexandros Stavrinadis, led by ICREA Prof. at ICFO Gerasimos Konstantatos, have developed CQD infrared-emitting LEDs with unprecedented values in the infrared range, an external quantum efficiency of 7.9 percent and a power conversion efficiency of 9.3 percent, a value never before attained with this type of device.

Feature - Work - Development - CQD - Structure

The key feature of this work has been the development of a CQD composite structure engineered at the suprananocrystalline level to reach unprecedentedly low electronic defect density. Prior...
(Excerpt) Read more at: phys.org
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