Yellow-light emitted single halide CsPbI3 nanowire

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-CsPbI3 nanowire indicate a promising application prospect in the field of luminescent devices.