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.