Control over seed framework enables oriented 3D nanocrystalline perovskite films for light-emitting diodes

Abstract

Crystallographic features strongly influence the luminescence and charge-transport properties of metal halide perovskite films; however, uncontrolled crystallization remains a major obstacle to developing efficient and stable perovskite light-emitting diodes (PeLEDs). Here we introduce a Lewis acid–base passivation strategy that modulates the formation of initial seed structures during film growth, enabling control over the crystallographic dimensionality, orientation, defect density, and grain size of the resulting films. By systematically investigating ligand-seed interactions, we demonstrate that careful tuning of ligand protophilicity induces additional coordination to the precursor species, thereby stabilizing desired seed configurations and guiding subsequent crystal growth. This strategy yields preferentially oriented and phase-pure three-dimensional (3D) nanocrystalline films while effectively suppressing defect-assisted nonradiative recombination through surface passivation. As a result, the films exhibit a photoluminescence quantum yield of 76%, a hole mobility of 2.22 × 10–4 cm2 V–1 s–1, and a reduced trap density of 3.09 × 1016 cm–3, along with enhanced thermal phase stability at 100 °C. PeLEDs based on these films achieve a maximum external quantum efficiency of 22.1% with minimal efficiency roll-off, maintaining an external quantum efficiency above 20% at 10,000 cd m–2.