Shallow defects and optical properties of CsPbBr3thin films through noble gas ion beam defect engineering.

Ion implantation is widely utilised for the modification of inorganic semiconductors; however, the technique has not been extensively applied to lead halide perovskites. In this report, we demonstrate the modification of the optical properties of caesium lead bromide (CsPbBr₃) thin films via noble gas ion implantation. We observed that the photoluminescence (PL) lifetimes of CsPbBr₃thin films can be doubled by low fluences (<1 × 10¹⁴at·cm^-2) of ion implantation with an acceleration voltage of 20 keV. We attribute this phenomenon to ion beam induced shallow minority charge carrier trapping induced by nuclear stopping, dominant by heavy noble gases (Ar, Xe). Simultaneously, the PL quantum yield (PLQY) is altered during noble gas ion implantation inversely correlates with the electronic stopping power of the implanted element, hence Ar implantation reduces the PLQY, while Ne even causes a PLQY enhancement. These results thus provide a guide to separate the effect of nuclear and electronic damage during ion implantation into halide perovskites.