Efficient Perovskite Light-Emitting Diodes with a Patterned Emitting Layer Formed through Inkjet-Printing-Induced Ion Exchange

Organic–inorganic halide perovskites possess a unique crystal structure that endows them with high luminescent efficiency, flexible spectra, and high color purity. As perovskite light-emitting diodes (PeLEDs) approach commercial maturity, patterning technologies that can deliver high-definition displays are urgently needed. Inkjet printing is a promising route, yet printed PeLEDs have so far exhibited modest external quantum efficiencies and luminance, hampering their practical deployment. Here, we merge in situ ion-exchange chemistry with inkjet patterning to fabricate hole-transport-layer-free electroluminescent devices in which two-dimensional (2D) perovskite precursors are converted into three-dimensional (3D) perovskites directly on the substrate. The resulting PeLEDs deliver a peak luminance of 10 730 cd/m 2 and a current efficiency of 12.11 cd/A performance metrics that establish inkjet-printed perovskite devices as competitive contenders for next-generation displays.