Solid Ligand-Assisted Storage of Air-Stable Formamidinium Lead Halide Quantum Dots via Restraining the Highly Dynamic Surface toward Brightly Luminescent Light-Emitting Diodes

Although organometal halide perovskites have garnered enormous interest in solar cells, scarce attention has been paid to light-emitting devices using formamidinium lead halide perovskite as the emitting layer. Highly luminescent and air-stable formamidinium lead halide perovskite quantum dots using high-melting-point ligands have been synthesized. Through compositional engineering, the emission spectra are readily tunable over the entire visible spectral region of 409–817 nm. The photoluminescence of FAPbX 3 nanocrystals has narrow emission line widths of 21–34 nm, high quantum yields of up to 88%, and a photoluminescence lifetime of 54.6–68.6 ns for single halide FAPbBr 3, which could be stable for several months. We have demonstrated the fabrication of highly efficient formamidinium lead halide perovskite quantum dot-based green-light-emitting diodes with a moderately high luminance of 33993 cd m –2, current efficiency of 20.3 cd A –1, and moderately high maximum external quantum efficiency of 4.07%.