Interference Crystallization Regulates Facet Orientation for Ultra‐Bright, Durable and Fast‐Responsive Perovskite Light‐Emitting Diodes

Metal halide perovskite light‐emitting diodes (PeLEDs) show immense potential in next‐generation display technologies due to their exceptional optoelectronic properties. However, their operational stability and luminescence brightness remain core bottlenecks restricting their commercialization. To address this issue, this study reports an interference crystallization strategy that regulates crystal facet growth to reshape facet competition. By incorporating L‐theanine (LT) into the precursor solution of FAPbBr 3 , the functional groups in LT selectively adsorb onto the (100) crystal facets of the perovskite, thereby suppressing the rapid growth of these facets and significantly enhancing the ordering of the crystal arrangement and crystal quality. Subsequently, 2,4,6‐Tris[3‐(diphenylphosphinyl)phenyl]‐1,3,5‐triazine (POT2T) is further introduced to modify the perovskite interface, synergistically passivating interface defects and confining the carrier recombination zone, thereby effectively suppressing interfacial non‐radiative recombination. Consequently, the fabricated green PeLEDs achieve an external quantum efficiency (EQE) of 23.06% and an ultrahigh luminance of 358 135 cd m −2 , delivering an outstanding T 50 operational lifetime of 14 923 h at an initial luminance of 100 cd m −2 . Furthermore, the optimized device with an active area of 6 mm 2 exhibits a response time of 1.01 µs. Thus, this strategy provides new insights for high‐luminance, long‐lifetime and fast‐response PeLEDs, broadening their potential applications.