A solar cell moonlights as an LED, both absorbing and emitting light more efficiently

Imagine a display that harvests ambient light when it is not actively in use, offsetting some of its own energy consumption. Materials physics shows that this is possible; the same semiconductor material can, in principle, emit and absorb light efficiently. What has been missing is a device architecture that allows it to do both without reductions in efficiency of either application. A new study reports a perovskite diode that converts sunlight to electricity at 26.7% efficiency (a world record at the time of publication) and emits light at 31% efficiency, figures that would be high for a device designed to do only one of those things. The work is published in the journal Joule.