π-π interface engineering enabled high-performance all-inorganic CsPbI3-xBrx perovskite solar cells using aniline derivatives

Uncontrolled crystallization and severe interfacial recombination stifle the lifespan and efficiency of all-inorganic CsPbI 3-x Brₓ perovskite solar cells. Therefore, this work introduces an aniline hydrochloride derivative additive, Benzenamine, N-[(2Z)-2-chloro-3-(phenylamino)-2-propen-1-ylidene]-, hydrochloride (BN), to improve the photoelectric performance and stability of the CsPbI 3-x Br x perovskite solar cells. The imine (C=N) groups coordinate with lead-related defects, the -NH 3 + groups form hydrogen bonds with halides, while the C Cl groups enhance lattice stability through electrostatic interactions. In addition, the aromatic skeleton in the BN molecule promotes ordered π-π stacking of molecules at the interface, which not only reduces surface energy but also constructs a hydrophobic protective layer. The optimized BN-based device achieved a maximum efficiency of 21.12%, significantly higher than the 17.27% of the control device. Furthermore, the optimized, unencapsulated device retained 95.6% of its initial efficiency after 1000 h of aging, demonstrating excellent environmental stability. This work validates the potential of aniline hydrochloride derivatives as highly efficient molecular modulators and provides a novel design approach for interface engineering in all-inorganic perovskite photovoltaic devices.