CsPbI3 exhibits remarkable performance in photovoltaic cells, yet maintaining phase stability under ambient conditions remains a primary challenge. To tackle this, we enhance phase stability through Bi-doping. The ionic and soft nature of the perovskite structure induces crystal lattice polarization and distortion around an injected charge carrier, forming a polaron quasiparticle. Polarons in perovskite solar cells significantly impact charge transport and recombination dynamics, influencing overall device performance. Researchers aim to optimize polaron dynamics, striking a balance between charge transport and recombination to enhance efficiency. Employing appropriate techniques is crucial to correlate structural distortion and polaron state. Our objective is to identify structural changes in illuminated Bi-doped CsPbI3, revealing varying solar cell efficiency based on Bi concentrations, and establish the relationship among Bi concentration, structural distortion, and polaron state.