4-Nitrophthalic Acid as an Additive for Low-Cost, Stable, and Efficient Carbon-Based Perovskite Solar Cells

Recent developments in perovskite solar cells (PSCs) have opened enormous possibilities for industrial applications. The quality of the perovskite film determines its efficiency and stability. Surface defects can negatively impact the solar cell performance. Additive treatment can efficiently minimize defect and trap states at the grain boundaries and surface of perovskite films. In this work, we introduce 4-Nitrophthalic acid (NPA) as an additive to improve perovskite film quality, crystalline structure, larger crystal grains, power conversion efficiency (PCE), and stability. NPA's carboxylic (-COOH), benzene, and nitro (-NO₂) groups interact with Pb²⁺ to significantly reduce surface defects. Moreover, the addition of NPA efficiently suppresses nonradiative recombination and enhances interfacial charge separation and transfer. The NPA additive's benzene group provides hydrophobic properties, enhancing the moisture stability of the fabricated CPSCs. The greatest PCE for carbon-based PSCs using a 2 mg of NPA device is 11.06%, which is higher than the control MAPbI₃ CPSCs (9.69%). Furthermore, the long-term stability of the CPSC with 2 mg of NPA added is considerably enhanced, and its PCE retains 84% of its initial value after being preserved for 650 h. Our results suggest that the NPA additive approach is a potential method for increasing the performance of PSCs.