Narrow‐Band Green‐Emitting Hybrid Organic–Inorganic Eu (II)‐Iodides for Next‐Generation Micro‐LED Displays

Abstract Low‐dimensional metal halide perovskites are an emerging class of light‐emitting materials for LED‐based displays; however, their B‐site cations are confined to ns 2 , d 5, and d 10 metals. Here, the design of divalent rare earth ions at B‐site is presented and a novel Eu(II)‐based iodide hybrid is reported with efficient (PLQY ≈98%) narrow‐band (FWHM ≈43 nm) green emission and high thermal stability (97%@150 °C). Owing to reduced lattice vibrations and shrunken average distance of Eu(II)‐iodide bonds in the face‐sharing 1D‐structure, photoluminescence from Eu(II) 4 f ‐5 d transition appears along with elevated crystal‐field splitting of 5 d energy level. The Eu(II)‐based iodide hybrid is further demonstrated for color‐pure green phosphor‐converted LEDs with a maximum brightness of ≈396 000 cd m −2 and photoelectric efficiency of 29.2%. High‐resolution micrometer‐scale light‐emitting diode (micro‐LED) displays (2540 PPI) via the solution‐processed screen is also presented. This work thus showcases a compelling narrow‐band green emitter for commercial micro‐LED displays.