Search
Menu
PI Physik Instrumente - Revolution In Photonics Align LW LB 3/24

Quantum Dot LEDs Incorporate Thermally Polymerized Hole Transport Layer

Facebook X LinkedIn Email
Anne L. Fischer

Colloidal semiconductor quantum dots show promise for use in optoelectronic devices such as LEDs and solar cells. Now a group led by David S. Ginger and Alex K.-Y. Jen at the University of Washington in Seattle has fabricated multilayer nanocrystal LEDs by spincoating a monolayer of colloidal CdSe/CdS nanocrystals atop polymerized hole transport layers.

Quantum-Dot.jpg

The hybrid quantum dot LED was made with a thermally polymerized hole transport layer and a spin-coated monolayer of orange-emitting CdSe/CdS quantum dots.

Ginger, an assistant professor of chemistry, said that the best devices use a single monolayer of quantum dots. The challenge was controlling the thickness of the quantum dot layer independent of the organic one.

The investigators found that spincoating the quantum dots from a chloroform solution onto the solventresistant, thermally cross-linked layer yields nearly pure electroluminescence from the quantum dots. By using a second solution-processible hole transport layer, they improved the efficiency to approximately 0.8 percent at a brightness of 100 cd/m2.

Ginger believes that the LEDs show such pure electroluminescence even with imperfect quantum dot layers because the carriers are confined to recombine very near the quantum dot layer. Alternatively, it is possible that the cross-linked hole transport polymer is less intrinsically electroluminescent than its more common molecular analogue.

The researchers believe that the performance can be further improved. They will work to optimize the energy levels and will create devices with multiple hole transport layers. They also expect to improve the photonic structure of the LED.

Nano Letters, online Feb. 1, 2006, doi: 10.1021/nl052417e.
DataRay Inc. - ISO 11146-Compliant

Published: April 2006
Glossary
nano
An SI prefix meaning one billionth (10-9). Nano can also be used to indicate the study of atoms, molecules and other structures and particles on the nanometer scale. Nano-optics (also referred to as nanophotonics), for example, is the study of how light and light-matter interactions behave on the nanometer scale. See nanophotonics.
Basic ScienceenergyFeaturesLight Sourcesnanonanocrystal LEDsoptoelectronic devicessemiconductor quantum dotsLEDs

We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.