Eu‐Based Porphyrin MOF Enables High‐Performance Carbon‐Based Perovskite Solar Cells

Abstract The low power conversion efficiency (PCE) of hole transport materials (HTM) – free carbon‐based perovskite solar cells (C‐PSCs) poses a challenge. Here, a novel 2D Eu‐TCPP MOF (TCPP; [tetrakis (4‐carboxyphenyl) porphyrin]) sandwiched between the perovskite layer and the carbon electrode is used to realize an effective and stable HTM‐free C‐PSCs. Relying on the synergistic effect of both the metal‐free TCPP ligand with a unique absorption spectrum and hydrophobicity and the EuO 4 (OH) 2 chain in the Eu‐TCPP MOF, defects are remarkably suppressed and light‐harvesting capability is significantly boosted. Energy band alignment is achieved after Eu‐TCPP MOF treatment, promoting hole collection. Förster resonance energy transfer results in improved light utilization and protects the perovskite from decomposition. As a result, the HTM‐free C‐PSCs with Eu‐TCPP MOF reach a champion PCE of 18.13%. In addition, the unencapsulated device demonstrates outstanding thermal stability and UV resistance and keeps 80.6% of its initial PCE after 5500 h in a high‐humidity environment (65%–85% RH).