Scientific American, Energy - Outshining Silicon, July 2015

Photo Editor Monica Bradley, Photo Plamen Petkov

Perovskite Solar Cells Could Beat the Efficiency of Silicon

An upstart material—perovskite—could finally make solar cells that are cheaper and more efficient than the prevailing silicon technology

By Varun Sivaram, Samuel D. Stranks and Henry J. Snaith

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Sitting in a dimly lit bar in Japan, then graduate student Michael Lee was scribbling on a beer coaster as night fell, jotting down a list of chemical ingredients before he forgot them. Earlier that day scientists at Toin University of Yokohama had generously shared their groundbreaking recipe for making solar cells from a new material called perovskite rather than the usual silicon. The cells were only 3.8 percent efficient in converting sunlight to electricity, so the world had not taken notice. But Lee was inspired. After the 2011 fact-finding mission, he returned to Clarendon Laboratory at the University of Oxford, where all three of us worked at the time, and made a series of tweaks to the recipe. The changes yielded the first perovskite cell to surpass 10 percent efficiency. His invention sparked the clean-energy equivalent of an oil rush, as researchers worldwide raced to push perovskite cells even higher.The latest record, set at 20.1 percent by the Korea Research Institute of Chemical Technology in November 2014, marked a fivefold increase in efficiency in just three years. For comparison, after decades of development state-of-the-art silicon solar cells have plateaued at about 25 percent, a target that perovskite researchers like us have squarely in our sights. We are also anticipating a commercial debut, perhaps through a spin-off company such as Oxford Photovoltaics, which one of us (Snaith) co-founded.



American Beauty, Paper magazine

For our American Dream issue, photographer Plamen Petkov and makeup artist and all-around creative powerhouse James Kaliardos teamed us to give us this breathtaking fashion story. In the following introduction, Kaliardos reveals the inspiration behind "American Beauty." 


When I was growing up outside of Detroit, my mother would borrow magazines from our public library that were filled with women of all ages and all colors. This became my early fashion and beauty training. I'd rip pages from Vogue, Bazaar and W (when it was a large newspaper) and make collages on the basement walls that were filled with models, celebrities and performers with every color of skin and every kind of face.

That's why it's been so strange to see the fashion industry take such a big turn toward milky homogenization. It just doesn't represent what is currently out there in popular culture or the real world. I've seen designers who sell millions in China, Japan and Korea fail to include a single Asian girl in a show. When a show of 100 girls has only one black girl, it sends out a very clear and unfortunate message. African-American pop stars may sing songs for millions of fans that popularize fashion labels, and yet women of color are nowhere to be seen on those same labels' ads or catwalks or in editorials. Diverse women sell music, movies and TV shows; they report the news and get voted into office. So why is the appearance of a woman like Serena Williams on the cover of Vogue (incredible on so many levels) so rare?

These days, fashion favors uniformity, an "army" of one type of girl. Hairdressers and makeup artists are often impossibly tasked with making this "army" look the same when each girl has different hair and facial features. As for me, I love the individual, and that is what diversity is all about. Each model in this story has her own identity, her own personality and her own beauty. The faces of America have never been just one color -- and neither has the definition of American Beauty. 

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