Bifunctional ligand passivation enables robust-stability perovskite nanocrystals for backlit display

Ligands are vital to the nucleation, growth, optical property and colloidal stability for perovskite nanocrystals (NCs). The traditional ligands using a combination of oleic acid and oleylamine ordinarily present highly dynamic and loose binding to the surface of perovskite NCs, leading to their poor stability, which will greatly hinder the performance of optoelectronic devices. Herein, two non-dynamic tight-binding X-type capping ligands of hexadecyltrimethylammonium tetrafluoroborate (THAB) and sodium 1-hexadecanesulfonate (SHS) were used to synthesize perovskite CsPbBr₃ NCs, respectively. The results indicated that bifunctional THAB capped NCs possessed a boosted photoluminescence quantum yield of 61 % owing to the effective defect passivation. More importantly, they showed superior stability against UV light, high temperature and polar solvent than SHS capped NCs. These elevated performances were further explained by the theoretical calculations, which showed that THAB could achieve a larger binding energy (−2.779 eV) than SHS (−2.320 eV). Lastly, we integrated the THAB capped CsPbBr₃ NCs into white light-emitting diodes, which possessed a wide NTSC color gamut of 121.7 %. This work not only provides a facile strategy to prepare high-brightness and excellent-stability perovskite NCs, but also extends the application of green emissive NCs in display fields.