Synergistic Effects of Multifunctional Lanthanides Doped CsPbBrCl₂ Quantum Dots for Efficient and Stable MAPbI₃ Perovskite Solar Cells

The passivation effect of inorganic perovskite quantum dots (PQDs) is a promising method to attain outstanding performance in perovskite solar cells (PSCs), which has ignited widespread interest recently. Lanthanides (Ln) doped PQDs demonstrate unique properties, but nevertheless, are not explored in PSCs. In this work, four kinds of Ln 3+ doped CsPbBrCl 2 PQDs (Ln 3+ = Yb 3+ , Ce 3+ , Eu 3+ , Sm 3+ ) are firstly introduced into PSCs, which displays the synergistic effect of composition engineering and defect engineering. The results indicate that the introduction of CsPbBrCl 2 : Ln 3+ can not only improve the crystallinity and passivate the intrinsic and surface defects of the MAPbI 3 layer through ion and ligand passivation, but also form a stronger LnI bond than PbI, adjust work function ( W F ), and optimize band alignments. CsPbBrCl 2 :Sm 3+ PQDs possess the best performance and exhibit remarkable promotions of open‐circuit voltage ( V oc ) from 1.13 to 1.20 V and power conversion efficiency from 18.54% to 22.52%. The humid‐resist, thermal‐resist abilities, and the long‐term stability of PSCs are energetically improved due to enhanced structure stability by Sm 3+ doping and the hydrophobic characteristic. The strategy of Ln 3+ doped PQDs applied to PSCs provide an approach to achieve high‐performance PSCs.