Two stories today in ScienceDaily point to different nanotech applications that could enable a solar solution to our energy problems—one including the use of self-repairing nanosystems. “Converting Sunlight To Cheaper Energy” describes the use of photoactive nanoscale systems to develop molecular electronics. Organic molecules and fullerenes will be used to make inexpensive photovoltaics and light emitting diodes:
Organic photovoltaics and organic LEDs are made up of thin films of semiconducting organic compounds that can absorb photons of solar energy. Typically an organic polymer, or a long, flexible chain of carbon-based material, is used as a substrate on which semiconducting materials are applied as a solution using a technique similar to inkjet printing.
…[South Dakota State University] scientists plan to use the variable band gap polymers to build multi-junction polymer solar cells or photovoltaics.
These devices use multiple layers of polymer/fullerene films that are tuned to absorb different spectral regions of solar energy.
Ideally, photons that are not absorbed by the first film layer pass through to be absorbed by the following layers.
The devices can harvest photons from ultraviolet to visible to infrared in order to efficiently convert the full spectrum of solar energy to electricity.
SDSU scientists also work with organic light-emitting diodes focusing on developing novel materials and devices for full color displays.
…The new technology will make it easy to insert lights into walls or ceilings. But instead of light bulbs, the lighting apparatus of the future may look more like a poster…
The second story describes how scientists are not only trying to exploit biology’s 3.7 billion year-old system for harvesting the sun’s energy, but planning to mimic it with artificial self-assembling and self-repairing nanodevices. From “Bacteria Power: Future For Clean Energy Lies In ‘Big Bang’ Of Evolution“:
Dramatic progress has been made over the last decade understanding the fundamental reaction of photosynthesis that evolved in cyanobacteria 3.7 billion years ago, which for the first time used water molecules as a source of electrons to transport energy derived from sunlight, while converting carbon dioxide into oxygen.
The light harvesting systems gave the bacteria their blue (“cyano”) colour, and paved the way for plants to evolve by “kidnapping” bacteria to provide their photosynthetic engines, and for animals by liberating oxygen for them to breathe, by splitting water molecules. For humans now there is the tantalising possibility of tweaking the photosynthetic reactions of cyanobacteria to produce fuels we want such as hydrogen, alcohols or even hydrocarbons, rather than carbohydrates.
Progress at the research level has been rapid, boosting prospects of harnessing photosynthesis not just for energy but also for manufacturing valuable compounds for the chemical and biotechnology industries. Such research is running on two tracks, one aimed at genetically engineering real plants and cyanobacteria to yield the products we want, and the other to mimic their processes in artificial photosynthetic systems built with human-made components. Both approaches hold great promise and will be pursued in parallel, as was discussed at a recent workshop focusing on the photosynthetic reaction centres of cyanobacteria, organised by the European Science Foundation (ESF).
…Among promising contenders discussed at the ESF conference was the idea of an artificial leaf that would simulate not just photosynthesis itself but also the ability of plants to regenerate themselves. This could be important, since the reactions of photosynthesis are destructive, dismantling the protein complexes where they take place, which therefore need regular reconstruction. Under a microscope, chloroplasts, the sub-cellular units where photosynthesis take place, resemble a permanent construction site, and even artificial systems would probably need some form of regenerative capability.
A future aim therefore is to build an artificial leaf-like system comprised of self-assembling nanodevices that are capable of regenerating themselves — just as in real plants or cyanobacteria. “Fundamental breakthroughs in these directions are expected on a time scale of 10 to 20 years and are recognized by the international science community as major milestones on the road to a renewable fuel,” said [Eva Mari Aro, the vice-chair of the ESF conference].
I found it particularly interesting that the researchers are thinking beyond simple nanodevices to harvest solar energy and considering self-repairing “leaf” systems in a 10-20 year time frame.
—Jim
