Zwitterionic Polymer: A Facile Interfacial Material Works at Both Anode and Cathode in p-i-n Perovskite Solar Cells

To improve the performance of perovskite solar cells (Pero-SCs), a betaine-based zwitterionic polymer poly(sulfobetaine methacrylate) (denoted by PSBMA) is employed as interlayers at both the anode and cathode in p-i-n Pero-SCs. 1) At the anode side, PSBMA acts as a glue to stitch the two interfacially unfavorable materials: perovskite and poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine), by which the quality of perovskite films as well as the corresponding device performance greatly improve. 2) At the cathode side, PSBMA smoothes the energy levels between PC61BM and Al, and thus facilitates the electron injection efficiency. The power conversion efficiency (PCE) is promoted from 17.31% to 19.16% after PSBMA is introduced as both anode and cathode sides of the p-i-n Pero-SCs. More importantly, PSBMA also shows great potential for large active area (1 cm x 1 cm) Pero-SCs, and a PCE as high as 15.7% is achieved.