Researchers improve quantum dot performance

Mon, 02/04/2013 - 7:32am
David L. Chandler, MIT News Office

The new quantum dots “combine all these attributes that people think are important, at the same time," says Moungi Bawendi, the Lester Wolfe Professor of Chemistry. Image: Qu ChenQuantum dots—tiny particles that emit light in a dazzling array of glowing colors—have the potential for many applications, but have faced a series of hurdles to improved performance. But a Massachusetts Institute of Technology (MIT) team says that it has succeeded in overcoming all these obstacles at once, while earlier efforts have only been able to tackle them one or a few at a time.


First discovered in the 1980s, these materials have been the focus of intense research because of their potential to provide significant advantages in a wide variety of optical applications, but their actual usage has been limited by several factors. Now, research published in Nature Materials by MIT chemistry postdoctoral researcher Ou Chen; Moungi Bawendi, the Lester Wolfe Professor of Chemistry; and several others raises the prospect that these limiting factors can all be overcome.

The new process developed by the MIT team produces quantum dots with four important qualities: uniform sizes and shapes; bright emissions, producing close to 100% emission efficiency; a very narrow peak of emissions, meaning that the colors emitted by the particles can be precisely controlled; and an elimination of a tendency to blink on and off, which limited the usefulness of earlier quantum dot applications.

Multicolored biological dyes



Quantum dots are also seen as potentially useful in creating energy-efficient computer and television screens. While such displays have been produced with existing quantum dot technology, their performance could be enhanced through the use of dots with precisely controlled colors and higher efficiency.

Combining the advantages

The new particles were made with a core of semiconductor material (cadmium selenide) and thin shells of a different semiconductor (cadmium sulfide). They demonstrated very high emission efficiency (97%) as well as small, uniform size and narrow emission peaks. Blinking was strongly suppressed, meaning the dots stay “on” 94% of the time.



Source: Massachusetts Institute of Technology


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