Letter abstract
Nature Materials 4, 138 - 142 (2005)
Published online: 9 January 2005 | doi:10.1038/nmat1299
Subject Categories: Optical, photonic and optoelectronic materials | Materials for energy | Nanoscale materials
Solution-processed PbS quantum dot infrared photodetectors and photovoltaics
Steven A. McDonald1, Gerasimos Konstantatos1, Shiguo Zhang1, Paul W. Cyr1,2, Ethan J. D. Klem1, Larissa Levina1 & Edward H. Sargent1
In contrast to traditional semiconductors, conjugated polymers provide ease of processing, low cost, physical flexibility and large area coverage1. These active optoelectronic materials produce and harvest light efficiently in the visible spectrum. The same functions are required in the infrared for telecommunications (1,300–1,600 nm), thermal imaging (1,500 nm and beyond), biological imaging (transparent tissue windows at 800 nm and 1,100 nm), thermal photovoltaics (>1,900 nm), and solar cells (800–2,000 nm). Photoconductive polymer devices have yet to demonstrate sensitivity beyond 
800 nm (refs 2,3). Sensitizing conjugated polymers with infrared-active nanocrystal quantum dots provides a spectrally tunable means of accessing the infrared while maintaining the advantageous properties of polymers. Here we use such a nanocomposite approach in which PbS nanocrystals tuned by the quantum size effect sensitize the conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV) into the infrared. We achieve, in a solution-processed device and with sensitivity far beyond 800 nm, harvesting of infrared-photogenerated carriers and the demonstration of an infrared photovoltaic effect. We also make use of the wavelength tunability afforded by the nanocrystals to show photocurrent spectra tailored to three different regions of the infrared spectrum.
- Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario, M5S 3G4, Canada
- Department of Chemistry, University of Toronto, Toronto, Ontario, M5S 3H6, Canada
Correspondence to: Edward H. Sargent1 e-mail: ted.sargent@utoronto.ca
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