Intragrain Heterostructure in 3D Perovskite: New Era of Bright PeLEDs with Low Efficiency Roll-Off
Solution-processed metal halide perovskite light-emitting diodes (PeLEDs) have advanced rapidly due to high color purity, tunable emission, and low cost, with external quantum efficiencies (EQEs) surpassing 30%. However, high EQEs are typically achieved at low brightness, suffering severe efficiency roll-off at high current densities due to Auger recombination and Joule heating. Three-dimensional (3D) perovskites offer superior charge transport but suffer from low photoluminescent quantum yield (PLQY) and efficiency roll-off. The fundamental roll-off mechanism remains poorly understood. Recently, Yao and co-workers developed a molecule-in-lattice-enabled intragrain heterostructure in 3D perovskite to promote carrier confinement. Using device-level ultrafast spectroscopy, they identified hole leakage as the origin of efficiency roll-off in pure-red CsPbI3−xBrx PeLEDs. A strong bonding small molecule with multiple anchor groups was introduced to penetrate the lead halide octahedron framework, constructing wide bandgap barriers inside perovskite grains, reducing hole leakage without compromising carrier transport. This approach enabled ultrabright, highly efficient, and stable pure-red PeLEDs with extremely low efficiency roll-off. The work provides a new strategy for achieving high brightness and efficiency simultaneously, advancing PeLED technology toward practical applications in displays and lighting.