http://techxplore.com/news/2016-06-perovskite-solar-cells-surpass-percent.html Michael Graetzel and his team found that, by briefly reducing the pressure while fabricating perovskite crystals, they were able to achieve the highest performance ever measured for larger-size perovskite solar cells, reaching over 20% efficiency and matching the performance of conventional thin-film solar cells of similar sizes. Their results are published in Science. via Perovskite solar cells surpass 20 percent efficiency.