Inhibiting Li+ migration by thenoyltrifluoroacetone toward efficient and stable perovskite solar cells

Lithium bis(trifluoromethanesulfonyl)imide is commonly employed as a dopant to improve the hole mobility of hole transport layers. However, undesired Li+ migration impedes the development of highly efficient and stable perovskite solar cells because the voids left by Li+ migration will accelerate the penetration of oxygen and moisture. Here, thenoyltrifluoroacetone (TTA) modifies the perovskite/spiro-OMeTAD interface. TTA can passivate the undercoordinated Pb2+ defects via the coordination between carbonyl/thiophenic sulfur and Pb2+. TTA can also inhibit the annoying Li+ migration by the coordination interaction between carbonyl and Li+. Besides, TTA can promote hole extraction by adjusting the energy level matching at the perovskite/hole transport layer interface. A TTA-modified device yields a power conversion efficiency of over 22% and has improved humidity and thermal stability. This finding paves a novel way to suppress undesired Li+ migration for highly efficient and stable PSCs.

Automated summary

Sodium salt ([CF3SO2]2N)Li is used as a dopant to enhance the mobility of hole transport layers, but unwanted Li+ migration hinders the development of efficient and stable perovskite solar cells due to the acceleration of oxygen and moisture penetration caused by voids left by Li+ migration. Here, thenoyltrifluoroacetone (TTA) is used to modify the perovskite/spiro-OMeTAD interface. TTA passivates undercoordinated Pb2+ defects and inhibits Li+ migration while promoting hole extraction and improving the energy level matching at the perovskite/hole transport layer interface. A TTA-modified device achieves a power conversion efficiency of over 22% and exhibits enhanced humidity and thermal stability.