Since the first CsPbX 3 perovskite solar cells (PSCs) made a power conversion efficiency (PCE) of 2.9% in 2015, their performance skyrocketed to an unprecedented value beyond 20%. [1,2] However, the black-phase CsPbX 3 tends to transfer into the nonperovskite phase at room temperature resulting in deterioration of photovoltaic performance. [3][4][5] To overcome these defects, massive efforts have been made by researchers, including developing new counterparts such as Ruddlesden-Popper (RP) CsPbI 3 and Dion-Jacobson (DJ) CsPbI 3 . [6,7] These types of 2D CsPbI 3 show improved stability for its hydrophobicity of the bulk aliphatic or alkylammonium cations (e.g., phenylethylammonium)), which would induce steric hindrance effect against the phase-transition process. [6][7][8] However, every coin has two sides. The organic cations also induce poor migration of photogenerated carriers in the perovskite film, which results in the low PCE of corresponding devices. [9][10][11][12] Recently, bulky-cation engineering is usually used to improve the carrier transition process of 2D perovskites (especially 2D RP type) by introducing organic cations with different sizes, charges, and shapes. Their carrier behaviors are improved in terms of their different suitabilities of hydrogen-bonding capacity, stereochemical configuration, and space-filling capability. [13][14][15] Li et al. demonstrated a novel bulky organic cation of 3-aminopropionitrile (3-APN) to construct pure 2D (3-APN) 2 PbI 4 with small I⋯I distance and favorable growth direction. 3-APN cation also induces intramolecular hydrogen bonding to align the energy level of the device for effective interfacial charge transfer. [16] Recently, Ren et al. presented a new bulky alkylammonium of 2-(methylthio) ethylamine hydrochloride (MTEACl) to realize sulfur-sulfur interaction, which enhanced charge transport and stabilized its framework. [17] Also, Xu et al. developed a series of multiplering aromatic ammoniums of 1-naphthalenemethylammonium (NpMA) and 9-anthracenemethylammonium (AnMA) to explore their difference in carrier behavior. It benefited from the hydrogen bonding formation between organic cations and inorganic layers, which ensured ultrafast exciton migration process for exciton separation, charge transition, and collection. [18] However, the exploration of organic cations in CsPbX 3 is limited to the common cations of PEA þ and BA þ . Some of the novel functional groups designed in organic cations could induce fantastic photoelectronic properties and device improvement as well.The chemical tuning of the spacer organic cation with fluoro (F) substitution has been widely explored for improving the basic properties of A-site cations. [19] Pan et al. demonstrated that F-substitution PEA þ is beneficial to improving the visible