Inorganic CsPbIBr2 perovskite features high phase stability and light absorption coefficient, making it suitable for the development of perovskite tandem cells or semi-transparent cells. High-quality CsPbIBr2 perovskite films are of crucial importance for fabricating efficient solar cells. However, in comparison with CsPbI3 and CsPbI2Br, the CsPbIBr2 precursor has poor crystallinity and low film coverage, which is prone to generating pinholes and defects. Therefore, serious charge recombination often occurs inside the devices. To address this problem, p-aminobenzoic acid (PABA) is added to the CsPbIBr2 precursor to regulate its crystallization dynamics in this work. Electrostatic potential distribution of PABA shows that the electron-rich regions (negative charge regions) are mainly located near the C=O. Fourier transform infrared spectroscopy indicates the existence of coordination interaction between C=O and Pb2+ and the formation of hydrogen bonds between -NH2 and halide anions. Ultraviolet-visible absorption (UV-Vis) spectroscopy and X-ray diffraction (XRD) spectra demonstrate that a new intermediate phase, PABA·Pb…Br(I), is formed between PABA molecules and the components of CsPbIBr2 precursor. The formation of this intermediate phase slows down the crystallization rate of the perovskite, regulates the grain growth, and enables the preparation of dense perovskite films. XRD, UV-Vis, space charge limited current, and linear sweep voltammetry are employed to characterize the film quality. After the addition of PABA, the film quality of CsPbIBr2 perovskite is improved. Thus, the light absorption is enhanced. The defect density is reduced. And the conductivity is increased. The efficiency of the champion cell increases to 10.65% compared to that of the control cell (8.76%). Further, dark current-voltage curves, Mott-Schottky curves, electrochemical impedance spectra, and photoluminescence spectra are utilized to analyze the reasons for the improved photovoltaic performance. After the addition of PABA, the CsPbIBr2 device exhibits reduced leakage current, enhanced built-in electric field, suppressed charge recombination, and improved charge extraction at the interface. In addition to the enhancement in photovoltaic efficiency, the PABA-regulated perovskite cells also exhibit high stability. After being stored in air for 1500 h, the average efficiency of the unencapsulated cells remains 80% of the initial value.