High-Voltage Stable Perovskite Light-Emitting Diodes Enabled by an Optoelectric-Tunable Sandwiched Nanostructure.

While metal halide light-emitting diodes (PeLEDs) with unique optoelectronic properties are promising emitters for next-generation displays, their performance degrades rapidly due to severe ion migration during continuous operation, especially at high voltages. Here, we realize highly stable PeLEDs by designing inorganic dielectric/perovskite semiconductor emitter/organic dielectric sandwiched nanostructures to mitigate ion migration via regulating the electric field distribution. The bilateral cesium carbonate (CsCO) and tetraoctylammonium bromide (TOAB) thin interlayers can not only largely reduce the voltage imposed on the perovskite layer by serving as series resistors and, thus, mitigate the ion migration but also regulate the charge carrier transfer to improve the radiative recombination efficiency. In addition, the underneath inorganic CsCO film also provides more heterogeneous nucleation sites for growing high-crystallinity perovskite crystals, while the atop TOAB with bifunctional groups (organic amino and Br ions) refines the morphology and enhances the optical properties of the perovskite film. As a result, efficient and stable green PeLEDs based on such an optoelectric-tunable nanostructure exhibit extremely slow efficiency decay as the applied voltage increases, and the external quantum efficiencies were maintained over 10% at a high bias up to 20 V.