Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. A researcher at Oxford PV’s pilot production facility in Brandenburg an der Havel, Germany, tests a commercial-size solar cell made by layering perovskite on silicon.Credit: Oxford PV The Henn na hotel in Nagasaki, Japan, is not shy of trialling futuristic technology. It claimed to be the world’s first robot-staffed hotel in 2015 — but cut down on the automation after its robotic concierges frustrated some customers and didn’t reduce costs. Now, the Henn na is testing another attention-grabbing innovation: since December, i...