Pyromellitic diimide-mediated bulk passivation for efficient perovskite solar cells with low energy loss
Perovskite solar cells (PerSCs) have achieved remarkable efficiencies, yet their performance is limited by defect states and non-radiative recombination. Here, pyromellitic diimide (PD) is introduced as an additive to passivate bulk defects in perovskite films. PD forms hydrogen bonds with formamidinium (FA+) ions and coordinates with Pb2+ ions, effectively suppressing non-radiative recombination and reducing energy loss. The PD-treated perovskite films exhibit enhanced crystallinity and uniformity. Consequently, 1.55 eV PerSCs achieve a high open-circuit voltage (VOC) of 1.193 V and a power conversion efficiency (PCE) of 25.79%. Moreover, unencapsulated PD-treated devices retain 96% of their initial efficiency after 2000 h under nitrogen atmosphere, whereas control devices retain only 74%. Under ISOS-D-2I accelerated aging (65±5°C in N2), PD-treated devices show less than 5% PCE attenuation after 288 h, compared to ~30% for controls. This work provides a viable strategy for defect passivation in perovskite solar cells, enhancing both efficiency and stability.