Research: Concentrating Sunlight
Inorganic nanocrystals are being investigated as a high efficiency material for luminescent solar concentrators.
Nanomaterials for improved luminescent solar concentrators
Luminescent solar concentrators (LSCs) have been studied for almost three decades, but their practical implementation has been limited by the quality of the materials available to absorb sunlight and re-emit it at useful wavelengths. Most LSCs studied so far have used small dye molecules, similar to the pigments used to color textiles and paper.
These molecules suffer from several shortcomings:
- They re-absorb some of the light that they emit, preventing it from reaching the photovoltaic device;
- They degrade under real-world operating conditions, limiting the lifetime of the LSC; and
- They work primarily at visible wavelengths, with no high-quality dyes available at the infrared frequencies that make up a large part of the sunlight hitting the earth.
Molecular engineering has started to address these issues, particularly the first one, but nanometer-scale design offers a new class of materials that may overcome all the problems and revolutionize LSCs. By carefully controlling chemical reactions in solution, scientists are able to make nanometer-scale crystals of semiconductor material that absorb and emit light efficiently. Moreover, they can build larger, hybrid structures that incorporate more than one kind of material, and they can control the size and shape of these structures. All this control over nanometer-scale structure makes it possible to engineer the colors of light absorbed and emitted by the materials, particularly in the previously inaccessible infrared frequency range. Argonne scientists are working on the challenges associated with producing high-quality, low-cost nanometer-scale materials that are stable, emit light efficiently, and can easily be incorporated into LSC structures.