Multifunctional Perylenediimide-Based Cathode Interfacial Materials for High-Performance Inverted Perovskite Solar Cells

Cathode interfacial materials (CIMs) are important to boost the device performance of perovskite solar cells (PVSCs). Herein, we reported two perylenediimide oligomers, PDI-D and PDI-T, which could play the role of an efficient multifunctional cathode interfacial layer (CIL) in the inverted PVSC. With the combinations of good orthogonal solvent solubility, interfacial dipole, self-doping, and interfacial doping in the PDI-T molecule, the contact barrier between the electron-transport layer and the metal cathode is obviously reduced. Adding to the induced good conductivity, the corresponding inverted PVSC with PDI-T as a CIL shows a promising power conversion efficiency (PCE) of 21.06% with simultaneously enhanced open-circuit voltage, current density, and fill factor. Moreover, thickness insensitivity of PDI-T CIL to PCE is also observed. Furthermore, good stability with a PCE loss of only 3.3% after 1032 h is also obtained. As such, it is concluded that the multifunctionalities from a single molecule in the CIM provide a new molecular insight for pursuing high-performance and stable inverted PVSCs.