Solar power windows

June 2, 2018
This article appeared in Berkeley Engineer magazine, Spring 2018

Slidesw showing transition from clear to opaque after heatingDemonstration of the transition from  clear to nearly opaque after heating slide. (Photo courtesy the researchers)Imagine windows that could automatically tint darker on a sunny day to block heat while also generating electricity. An invention from a research team led by Peidong Yang, a professor with appointments in  materials science and engineering and chemistry, could lead to this type of power-producing smart window for buildings, cars and display screens. The scientists altered the chemical structure of perovskite, a versatile material that already rivals silicon-based solar cells, so that the material turns from transparent to opaque when heated and also converts sunlight into electricity. While the sunlight conversion efficiency of the material — an inorganic halide perovskite with added cesium, lead, iodine and bromine — is still low, and the transition from transparent window to opaque solar cell requires heating the window to the boiling point of water, Yang and his group are already at work on versions that work at lower temperatures and with higher conversion efficiency.