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.