Weakly Space-Confined Perovskites: A Promising Strategy to Overcome PeLEDs Limitations
Halide perovskite light-emitting diodes (PeLEDs) have advanced rapidly due to their high photoluminescence quantum yield, tunable bandgap, and color purity. However, conventional perovskites exhibit small exciton binding energies, which weaken radiative recombination and limit external quantum efficiency (EQE). Strong spatial confinement strategies, such as thin films, small grains, or quantum-confined structures, have boosted EQE beyond 20% but introduce Auger recombination and ion migration, causing efficiency roll-off and instability. This commentary highlights a novel approach by Xiao et al. (Nature, 2025) that employs weakly space-confined all-inorganic CsPbBr3 perovskites, synthesized using sacrificial additives hypophosphorous acid (HPA) and ammonium chloride (NH4Cl). This method yields highly oriented monocrystalline domains exceeding hundreds of nanometers with no observable grain boundaries, contrasting with control films (submicrometre grains with abundant boundaries) and strongly confined systems (~20 nm crystallites with organic ligands). The reduced grain boundaries lower defect density and block ion migration, while controlled crystallization suppresses vacancies and lattice distortions, enhancing carrier mobility and raising the ion migration energy barrier. The strategy achieves record-breaking performance and stability, addressing EQE roll-off and operational lifetime limitations. This approach offers a versatile framework for other all-inorganic perovskite systems, advancing PeLEDs toward practical high-brightness displays and lighting.