Synergetic Interface and Bulk Defects Modification with Identical Organic Molecule for Efficient Inverted Perovskite Solar Cells

Recent progress in inverted perovskite solar cells (IPSCs) mainly focused on NiO x modification and perovskite (PVK) regulation to enhance efficiency and stability. However, most works address only monofunctional modifications, and identical molecules with the ability to simultaneously optimize NiO x interface and perovskite bulk phase have been rarely reported. This work proposes a dual modification approach using 4-amino-3,5-dichlorobenzotrifluoride (DCTM) to optimize both NiO x upper interfaces and reduction of bulk defects in perovskite. Amino group in DCTM increases the Ni 3+ /Ni 2+ ratio in NiO x, thereby increasing the conductivity and optimizing the energy alignment. Additionally, DCTM fills Pb 2+ and I – vacancies in perovskite, which improves the vertical orientation of perovskite grains and subsequently reduces nonradiative recombination, thereby achieving the increased carrier lifetime. PVK modified by DCTM exhibits enhanced energy level alignment with the electron transport layer, while femtosecond transient absorption (TA) spectroscopy confirms that DCTM facilitates efficient carrier transport, leading to high-performance IPSCs. The optimized IPSCs achieve a maximum efficiency of 22.8% with a reduced hysteresis (0.7%). Moreover, the unencapsulated device preserves over 80% of its initial power conversion efficiency (PCE) after 1000 h stored in air at 30% relative humidity. This dual modification strategy of monomolecular offers a straightforward solution for interface optimization and provides new insights into selecting aniline-derived molecules for high-performance IPSCs.