One-step deposition 0D/3D perovskite heterojunction films enabled by co-additive crystallization control for efficient perovskite LEDs

A facile co-additive crystallization strategy fabricate 0D/3D perovskite heterojunctions via a one-step spin-coating route. • FABr induces in-situ formation of 0D Cs₄PbBr₆, NEABr regulates crystallization kinetics and passivates defects. • The optimized 0D/3D heterostructure enables reduced defect density, balanced charge injection, suppressed ion migration. • Green PeLEDs based on this heterojunction achieve a peak EQE of 7.81% and an ultrahigh luminance of 51823 cd m⁻². Metal halide perovskites have emerged as promising semiconductors for next-generation displays, featuring high electroluminescence efficiency and outstanding color purity. Three-dimensional (3D) perovskites offer superior charge transport but suffer from moderate exciton binding energies that limit radiative recombination. In contrast, zero-dimensional (0D) Cs₄PbBr₆ provides strong exciton confinement. However, controllable integration of 0D perovskites into 3D matrices via solution‐processable routes remains challenging. Here, we report a co-additive crystallization modulation strategy that enables in-situ fabrication of uniform 0D/3D perovskite heterojunction films active layer through a one-step deposition process. Formamidinium bromide (FABr) promotes the formation of 0D Cs₄PbBr₆ nanocrystals, while 1-naphthylethylammonium bromide (NEABr) regulates crystallization kinetics via steric hindrance and coordination effects, yielding improved film morphology and suppressed defect formation. The synergistic effects reduce defect density, balance charge injection, and enhance light outcoupling. Consequently, green perovskite light-emitting diodes (PeLEDs) based on the optimized 0D/3D heterojunctions deliver a peak luminance of 51823 cd m⁻² and a maximum external quantum efficiency (EQE) of 7.81%. This work provides a straightforward and scalable crystallization-control strategy for constructing functional 0D/3D perovskite heterostructures, offering rational design principles for high-performance perovskite optoelectronic devices. Download: Download high-res image (207KB) Download: Download full-size image A one-step spin-coating strategy using dual additives (FABr + NEABr) enables in-situ fabrication of uniform 0D/3D perovskite heterojunction films. FABr promotes formation of 0D Cs 4 PbBr 6 nanocrystals, while NEABr regulates crystallization kinetics, reducing defects and improving morphology. The resulting 0D/3D heterojunctions balance charge injection and enhance light outcoupling, delivering green PeLEDs with a peak luminance of 51823 cd m⁻² and a maximum EQE of 7.81%.