Sky-blue perovskite light-emitting diodes based on quasi-two-dimensional layered perovskites

A mixed organic (4-phenylbutylamine, 4-PBA) and inorganic (cesium, Cs) cations are used to deposit quasi-two-dimensional layered perovskites. This layered perovskites exhibit good film coverage as two-dimensional perovskites and high emission performance close to three-dimensional organic–inorganic hybrid perovskites. Light-emitting diodes (LEDs) are fabricated by using solution process based on the quasi-two-dimensional layered perovskites. The perovskite LEDs exhibit a sky-blue emission with electroluminescence peak at 491 nm and a low turn on voltage at 2.9 V. The maximum external quantum efficiency reaches 0.015% at brightness of 186 cd/m².