When it comes to 3D printing, the sky is the limit. As 3D printing technology continues to advance, applications can be as far reaching as airplane and automobile parts to medical devices and even anatomically correct, biocompatible models. Although 3D printing technology is developing at a rapid pace, the technology itself is not new. It emerged in the 1980s as a means of creating rapid prototypes. In recent years the applications for 3D printed models have evolved with the available hardware, software, and printable materials. Evolving technology, paired with the creative and innovative minds of scientists, engineers, and physicians, has been the launching pad for developments within 3D printing technology specific to healthcare. One way 3D printing technology is poised to create better patient outcomes is in creating an anatomically and patient-specific models to aid in surgery and medical procedures. With the capability to 3D ...
Silicon solar cells are efficient and getting cheaper, but polymer solar cells can be made of a thin plastic and are less expensive to produce. Now there’s another contender in the race: small molecules.
Katherine Bourzac explains in Technology Review:
Organic materials — whether made of polymers or so-called ‘small molecules,’ which are organic compounds with a low molecular weight — can be made into inks and printed over large areas. They’re also lightweight and flexible, which makes them promising for applications like rooftop installations or solar-cell patches for charging portable electronics.
“Solar cells fabricated from small donor molecules can compete with their polymeric counterparts,” wrote Alan Heeger and Guillermo Bazan and colleagues in a journal article. The chemistry professors at the University of California, Santa Barbara, and colleagues reported a solar cell with demonstrated efficiency of 6.7%. This number is just below the 9% of the light that the best polymer solar cells on the market can convert to energy. Bazan told Technology Review that he expects to reach 9% efficiency within a year by further tailoring the properties of the material.
Heeger describes in the video (above) what all solar cell materials have to do: Absorb photons, separate the charges in the photons, and collect those separated charges at an electrode.
Heeger told Bourzac that although other people had tried using small-molecule solar materials to do those tasks in the past, he had not taken them seriously because the performance was far below polymers. He said the efficiencies have reached a respectable level, and “now we should take them seriously.”
Heeger built the solar cell using a small molecule that Bazan designed. Bourzac describes Bazan’s process:
Bazan used a combination of theory and trial-and-error to develop the new small molecule material. He started by optimizing its electrical properties, so that the molecule would be able to support the high current and voltage needed to get power out of a solar cell. It’s especially tricky to create a small-molecule material that makes a good film; while polymers are long and get tangled into a stable film, small molecules don’t tend to make the kind of planar films needed to make a layer in a solar cell.
Yang Yang, professor of materials science and engineering at the University of California, Los Angeles, is aiming for 15% efficiency in a lab-made cell. He works on polymer cells at his company, Solarmer, and small-molecule cells in his university lab. Although the Santa Barbara work is important, it will be hard to beat silicon or polymer cells, he told Technology Review.
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