Hybrid Si quantum-dot LED produces strong blue-white light

July 10, 2015
A silicon quantum-dot-based hybrid inorganic/organic LED that exhibits white-blue electroluminescence has been developed.
Content Dam Lfw Print Articles 2015 07 1507lfw Nb02 Web
Content Dam Lfw Print Articles 2015 07 1507lfw Nb02 Web
Content Dam Lfw Print Articles 2015 07 1507lfw Nb02 Web
Content Dam Lfw Print Articles 2015 07 1507lfw Nb02 Web
Content Dam Lfw Print Articles 2015 07 1507lfw Nb02 Web

A silicon quantum-dot (Si QD)-based hybrid inorganic/organic LED that exhibits white-blue electroluminescence (EL) and is fabricated by solution processing has been developed by a group at Hiroshima University (Hiroshima, Japan). The QDs were fabricated using pulsed laser ablation of a crystalline Si wafer placed in a 1-octyne solvent fluid; it took several 8 h periods to create enough Si QDs, which were then filtered through a membrane with a 100 nm pore diameter and dried under vacuum.

To fabricate the 4 mm2 LED, hole-injection and hole-transport layers were spun onto a prepatterned indium-tin-oxide (ITO)-coated glass substrate, with the ITO forming the anode. Subsequently, a 66-nm-thick Si QD emission layer in a solution was spin-coated and thermally annealed, followed by an electron-transport layer and a cathode. The LED produces a spectrum (red line is original data; black line is fitted) that has a small amount of EL around 2 eV (620 nm), increases sharply at 2.5 eV (496 nm), and peaks at 3 eV (413 nm). The output is about 78% from the Si QDs, with the rest coming from the organic matrix. The researchers determined that the very uniform light emission of the LED, in contrast to that of a purely organic LED, was due to the addition of the Si QDs.

Reference: Y. Kin et al., Appl. Phys. Lett. (2015); http://dx.doi.org/10.1063/1.4921415.

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.

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