Despite the progress in perovskite device efficiencies, these systems are not fully understood, in particular the frequency- and power-dependence of their response to light. Yu-Hwa Lo and colleagues at the University of California in San Diego (UCSD) now report on systematic investigations of how these devices respond to light for frequencies varying over eight orders of magnitude and power ranging from millions to single photons.

Paper-thin optical lenses simple enough to mass produce like microchips could enable a new generation of compact optical devices.