Interface modification by Fmoc-Met-OH molecule for high-efficient perovskite solar cells

The numerous defects on the surface and grain boundaries of polycrystalline perovskite after solution treatment would seriously affect the performance of organic–inorganic hybrid perovskite solar cells. Interface modification is considered to be an effective method to reduce defects of the perovskite films. In this work, a multi-functional amino acid molecule, Fmoc-Met-OH, was introduced into anti-solvent solution to delay the crystallization of perovskites for high-quality perovskite films. Systematic study demonstrates that amino acid molecules play a significant role in promoting the morphology and crystal structure of perovskite films. The surface trap states of perovskite films are reduced by the interaction of Fmoc-Met-OH functional groups with the uncoordinated metal cation of perovskite, resulting in inhibition of charge recombination and enhanced charge transport. The efficiency of the modified device can reach up to 16.75% compared to 14.17% of the control counterpart. Moreover, the unpackaged device exhibited good stability and can retain 65% of the initial efficiency after being stored in air atmosphere at 30% humidity for 220 h.