Quantum Dot Light Bulbs

Vladimir Bulovic
Organic and Nanostructured Electronics Laboratory
Research Laboratory of Electronics

Artificial lighting consumes 8% of US energy and 22% of US electricity, with the energy cost estimated at $50 billion annually or $200 per capita [U.S. DOE, Basic Research Needs for Solid-State Lighting, May 2006]. The energy cost associated with the ubiquity of artificial lighting is exacerbated by the continued use of Edison’s incandescent technology, in which 95% of the energy is expended to heat a tungsten filament to 3000°C, and only 5% is emitted as visible light. Incandescents account for 12% of the lights used today. Fortunately, alternative technologies are in use, dominated by fluorescent lighting, which operates at 20% conversion efficiency and accounts for 62% of the light bulbs used today, and high intensity street lamps
that operate at 25% conversion efficiency and account for the remaining 26% of light bulbs. By contrast, electric motors are 85~90% efficient [U.S. DOE]. So what can we do to make light bulbs more efficient?

Photographs of QD-LED pixels at applied bias voltage of 6 V for blue and cyan, 4 V for green and orange, and 5 V for red. (middle) Emission spectra of QD-LEDs, corresponding to the pictures above. (bottom) Photograph of the chloroform solutions of different QD types, with their composition indicated. Photoluminescence of QD solutions is excited by an ultra-violet light lamp. (image: Vladimir Bulovic).

Photographs of QD-LED pixels at applied bias voltage of 6 V for blue and cyan, 4 V for green and orange, and 5 V for red. (middle) Emission spectra of QD-LEDs, corresponding to the pictures above. (bottom) Photograph of the chloroform solutions of different QD types, with their composition indicated. Photoluminescence of QD solutions is excited by an ultra-violet light lamp. (image: Vladimir Bulovic).

Researchers in the lab of Prof. Vladimir Bulovic are developing LED light bulbs that consist of thin solid films of nanostructured materials of inorganic nanocrystal quantum dots (QDs), which have been colloidally synthesized by the chemistry group of MIT Chemistry Prof. Moungi Bawendi. These structures aim to extend the performance of the state of the art solid state lighting (SSL) technology, such as the white LEDs (with 35% efficiencies), and to develop methods for scalable manufacture and broad deployment of SSL.

The completed QD-LED structures are large-area emitters consisting of a single layer or multi-layers of QDs embedded between organic [Coe et al., Nature 420, 800 (2002)] or inorganic charge transport films [Caruge et al., Nature Photonics 2, 247 (2008)]. To date, the Bulovic-Bawendi collaboration has demonstrated QD-LED color emission across the visible part of the spectrum and from 1.3?m to 1.6?m in infra-red. Their QD-LED performance is comparable to the power consumption of organic LEDs (OLEDs) presently used in cell phones and their ultimate performance could match the best inorganic LED technologies. Akin to mixing colors in a paint shop, the solutions of QD can also be precisely mixed to achieve any desired spectrum including the recently demonstrated white emission of QD-LEDs, as would be needed for SSL [Anikeeva et al. Nano Letters 7, 2196 (2007)]. Technological successes in the lab have spurred development of a QD technology start-up, QD Vision, in Watertown, Massachusetts.

2 Responses to “Quantum Dot Light Bulbs”

  1. I like the fact that flexible OLEDs have a quicker response time than LEDs!

  2. Jean MARIE says:

    I’m researching for microscope lighting using leds instead of classic bulbs or mercury lamps.So,qd leds seem to be an opportunity for microscopy,especially for epifluorescence.Is it possible to find a device allowing the control of the wawelength emitted by qd leds (to fit photophores)? It could allow longlasting op&rational simplicity at lower costs (I think of “colibri”led system from Zeiss ).Do you know some reseaches on this subject?Thank you.

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