The characteristics of perovskite solar cells (PSC) are affected by interface traps. In this work, we introduce an interfacial modifier based on polyaspartic acid sodium (PASP) that is incorporated between a methylammonium lead iodide (MAPbI3) photo-absorber and P3CT-Na hole transporting layer. PASP contains a large number of –COO− anions and Na+ cations, thus enabling a strong chelating cooperation for metal polyvalent ions. The incorporated PASP leads to an effective passivation of the surface traps originating from Pb2+ and I− in MAPbI3 and control over the crystallization of MAPbI3 with slightly enlarged grains. The combined benefits with the introduced PASP enable boosting the power conversion efficiency to 20.05% with an impressive FF of 82.20% in MAPbI3 based p–i–n PSCs.
