Refining perovskite heterojunctions for effective light-emitting solar cells.

Solar cells capable of light-harvesting during daytime and light-emitting at night are multifunctional semiconductor devices with many potential applications. Here we report that halide perovskite heterojunction interfaces can be refined to yield stable and efficient solar cells. The cell can also operate effectively as an ultralow-voltage light-emitting diode with a peak external quantum efficiency of 3.3%. Spectroscopic and microscopic studies reveal that double-heterojunction refinement with wide-bandgap salts is key to densifying the packing of perovskite grains and enlarging the bandgaps of the perovskite surfaces that are in contact with charge transport semiconductors. The refined perovskite enables a simple device with dual actions of solar cells and light-emitting diodes. This type of all-in-one device has the potential for multifunctional harvesting-storage-utilization systems. This article is protected by copyright. All rights reserved.