Inorganic perovskite compounds hold promise to improve the stability of perovskite solar cells (PSCs). However, the phase instability and high annealing temperature process of these metastable structural polymorphs such as α-phase CsPbI3- xBr x hinder their further development. Herein, we demonstrated the successful reduction of temperature from 250 to 100 °C during the growth of stable and high-crystallinity α-phase CsPbI2Br via crystal cross-linking. 4-Aminobenzoic acid (ABA) was used as a nonvolatile additive with slight solubility in water to bridge the adjacent CsPbI2Br to form a grain-interconnected film. The interaction between ABA and perovskite grains leads to the growth of highly crystalline perovskite films. The optimized PSC based on ABA-incorporated CsPbI2Br using a TiO2/Al2O3/NiO/carbon architecture exhibits an efficiency of 8.44%. More importantly, the additive enables significant improvement of phase stability against moisture. The good performance highlights the chemical modification via cross-linking to achieve efficient and stable inorganic perovskite devices.