High-Voltage\nStable\nPerovskite Light-Emitting Diodes\nEnabled by an Optoelectric-Tunable Sandwiched Nanostructure

While metal halide light-emitting\ndiodes (PeLEDs) with\nunique optoelectronic\nproperties are promising emitters for next-generation displays, their\nperformance degrades rapidly due to severe ion migration during continuous\noperation, especially at high voltages. Here, we realize highly stable\nPeLEDs by designing inorganic dielectric/perovskite semiconductor\nemitter/organic dielectric sandwiched nanostructures to mitigate ion\nmigration via regulating the electric field distribution. The bilateral\ncesium carbonate (Cs<sub>2</sub>CO<sub>3</sub>) and tetraoctylammonium\nbromide (TOAB) thin interlayers can not only largely reduce the voltage\nimposed on the perovskite layer by serving as series resistors and,\nthus, mitigate the ion migration but also regulate the charge carrier\ntransfer to improve the radiative recombination efficiency. In addition,\nthe underneath inorganic Cs<sub>2</sub>CO<sub>3</sub> film also provides\nmore heterogeneous nucleation sites for growing high-crystallinity\nperovskite crystals, while the atop TOAB with bifunctional groups\n(organic amino and Br<sup>–</sup> ions) refines the morphology\nand enhances the optical properties of the perovskite film. As a result,\nefficient and stable green PeLEDs based on such an optoelectric-tunable\nnanostructure exhibit extremely slow efficiency decay as the applied\nvoltage increases, and the external quantum efficiencies were maintained\nover 10% at a high bias up to 20 V.