Grain Boundary Passivation Using D131 Organic Dye Molecule for Efficient and Thermally Stable Perovskite Solar Cells

The efficiency of perovskite solar cells (PSCs) has achieved the milestone of 25% with a high speed over the past decade. However, miscellaneous defects at grain boundaries and interfaces have significantly influenced the durability and efficiency of PSCs. In this work, D131 dye, an indoline molecule with a Donor–Acceptor structure, has been introduced into a perovskite precursor as an additive for the first time. The terminal cyanoacrylic acid group of D131 with intense negative charges can interact with Pb2+ in the precursor to retard crystallization and enhance crystallinity. Moreover, the D131 molecule can stably passivate the undercoordinated Pb2+ defects at grain boundaries and enhance the thermal and humid stability of perovskite films. As a result, a photovoltaic conversion efficiency (PCE) up to 21.38% (18.55% for 1 cm2 active area device) has been achieved for the cell with the D131 additive, and the nonencapsulated cell can retain over 81% of its initial PCE after 1100 h of storage (25 °C, 15 ± 5% relative humidity), thus providing a new strategy for durable and high-performance PSCs.