posted on 2021-11-09, 17:39authored byQiuhong Chen, Sheng Cao, Ke Xing, Meijing Ning, Ruosheng Zeng, Yunjun Wang, Jialong Zhao
CsPbI3 perovskite nanocrystals (NCs) are emerging as
promising materials for optoelectronic devices because of their superior
optical properties. However, the poor stability of CsPbI3 NCs has become a huge bottleneck for practical applications. Herein,
we report an effective strategy of Mg2+-assisted passivation
of surface defects to obtain high emission efficiency and stability
in CsPbI3 NCs. It is found that the introduced Mg2+ ions are mainly distributed on the surface of NCs and then passivate
the NC defects, enhancing radiative decay rate and reducing nonradiative
decay rate. As a result, the as-prepared Mg2+-treated CsPbI3 (Mg-CsPbI3) NCs exhibit the highest photoluminescence
quantum yield (PLQY) of 95%. The Mg-CsPbI3 NC colloidal
solution retains 80% of its original PLQY after 80 days of atmosphere
exposure. The red perovskite light-emitting diodes based on the Mg-CsPbI3 NCs demonstrate an external quantum efficiency of 8.4%, which
shows an almost 4-fold improvement compared to the devices based on
the untreated NCs.