Surface-Binding Molecular Multipods Strengthen Halide Perovskite Lattice and Improve Luminescence Efficiency

The luminescence efficiency of perovskite light-emitting diodes (LEDs) has been significantly advanced by reducing the size of perovskite crystals with passivation of surface defects. Nevertheless, the remaining gap between the optical limit of electroluminescence efficiency and photoluminescence efficiency (PLQY) of colloidal perovskite nanocrystals (PeNCs) indicates that merely passivating defects are not enough to achieve highly efficient PeNC-LEDs. In this study, we propose a materials-based strategy, which utilizes conjugated molecular multipods (CMMs), to control the dynamic nature of the perovskite surface. Our experimental and theoretical analyses demonstrate that CMMs adsorb to the perovskite surface through multipodal hydrogen bonding and van der Waals interactions. These interactions strengthen the near-surface perovskite lattice and mitigate ionic fluctuations, which reduce non-radiative recombination. The CMMs effectively strengthen the perovskite lattice and reduce dynamic disorder, leading to a near-unity PLQY for PeNC films and a high external quantum efficiency (26.1%) for PeNC-LEDs. PeNC-LEDs with CMMs exhibit pure green emission that closely approaches to green primary color in Rec. 2020 standard, suitable for next-generation vivid displays.