Green-white color switchable light-emitting devices based on laterally fused cesium lead bromide perovskite nanowires

摘要

Inorganic lead halide perovskites are excellent optoelectronic semiconductors; however, little has been known about the characteristics of their nanowire-based light-emitting devices (LEDs). We study the LEDs employing self-assembled CsPbBr_3 nanowires as emission layers. They tend to form crystallographic orientation-consistent laterally fused parallel arrays when self-assembling into the emission layer in the device due to Coulomb attraction between such ionic semiconductors. At high nanowire concentration, the LED emits pure green light, and the carriers transport through Fowler-Nordheim (FN) quantum tunneling and direct injection successively. In contrast, at lower nanowire concentration, the luminescence of the LED shifts gradually from green to white with the increasing bias owing to participation of not only the nanowire layer but also the carrier transport layers in the carrier recombination processes. Meanwhile, its carrier transport experiences successively FN quantum tunneling, direct quantum tunneling, and direct injection with the increasing bias. These results highly improve our understanding of the characteristics of perovskite nanowires-based LEDs.