Yellow-light emitted single halide CsPbI3 nanowire

•Herein, by using a modified ligand-assistant reprecipitation (LARP) method at room temperature of the ambient atmosphere.•Single halide yellow-light emitted CsPbI3 nanowire with excellent luminescence monochromaticity is successfully synthesized, which even presents a record high PLQY of 94% and large binding energy up to 212.5 meV.•Atomic-scaled structural characterizations figure out that oleic acid (OA) ligands were inserted into the lattice of CsPbI3 nanowire forming a new crystal structure. Such a unique structure triggers the photoexcited carriers bypassing the trap state level in the bandgap and enhancing the radiative excitons lifetime.•This is the first time to regulate the emission wavelength of single halide CsPbI3 from red light emission to yellow light emission, especially by adopting an ultimate quantum confinement effect strategy of the OA-CsPbI3 nanowire. Furthermore, the excellent thermal and damp air stabilities of the newly formed nanowire indicate its good application prospect in the field of luminescent devices. With the rapid development of metal halide perovskite, reducing its dimensionality into two-dimensional (2D) or one-dimensional (1D) nanostructures has been reported to be a good alternative for expanding the spectral absorption or emission range. For example, when substituting monovalent cation Cs+ with phenylethylammonium (PEA+) on fabricating 2D-CsPbI3, the photoluminescence peak processes a maximum regulation from 710 to 625 nm. Simultaneously, when slicing into 1D CsPbI3 nanowires, the light emission could also achieve a maximum blue shift from 700 to 600 nm. Herein, by using a ligand-assistant reprecipitation (LARP) method, oleic acid (OA) molecule is successfully inserted into the lattice of one-dimensional CsPbI3 nanowire (namely OA-CsPbI3), which presents a monochromatic yellow light emission at 558 nm with narrow emission-band (about 28 nm), and records high photoluminescence quantum yield (PLQY) of 94%. Such a yellow-light emission in single halide CsPbI3 systems has never been discovered before. Meanwhile, a shallow energy level in the OA-CsPbI3 nanowire is further identified by the ultrafast transient absorption (TA) and first-principle calculation, which helps the photoexcited carriers bypass the trap state level in the bandgap and enhances the radiative excitons lifetime with maximum binding energy up to 212.5 meV. What's more, the excellent thermal and moisture stabilities of the newly formed one-dimensional OA