Synthesis and photoluminescence kinetics of Ce³⁺-doped CsPbI₃ QDs with near-unity PLQY

CsPbI₃ perovskite quantum dots (QDs) have great potential in optoelectronic devices due to their suitable band-gaps, but low photoluminescence quantum yields (PLQYs) and poor phase stability seriously impede their practical application. This paper reports the synthesis of Ce³⁺-doped CsPbI₃ QDs by a hot injection method. In the presence of the dopant (Ce³⁺), the highest PLQY of CsPbI₃ QDs reached 99%, i.e., near-unity PLQY, and the photoluminescence (PL) emission of CsPbI₃ QDs could be well maintained compared to that of the undoped ones. The photoluminescence kinetics of Ce³⁺-doped CsPbI₃ QDs was investigated by the ultrafast transient absorption technologies, which exhibited that the Ce³⁺ not only increased the density of excitonic states close to the high energy excitonic states (HES), but also provided more emissive channels. Moreover, the radiative recombination rates calculated by the combination of PL lifetime and PLQY further illustrated the Pb²⁺ vacancies were filled with Ce³⁺ ions so that the PL quenching of the CsPbI₃ QDs could be effectively prevented. The theoretic analysis uncovered the mechanism of the high PLQY and stable PL emission of the Ce³⁺-doped CsPbI₃ QDs.