 This study proposes using Cl2 dissolved chloroform as a multifunctional solvent for simultaneously constructing 2D, 3D perovskite heterojunctions and inducing the secondary growth of the bulk grains. This process leads to the formation of Cl ions which diffuse into the bulk crystals and passivate the surfaces of the perovskite solar cells. Additionally, heterozolemonium bromide dissolved in the solvent reacts with the remaining lead iodide to create 2D, 3D heterojunctions on the surface. These heterojunctions improve the performance of the perovskite solar cell by increasing its efficiency from 24.21 percent to a record breaking 24.21 percent. Furthermore, this process also improves the thermal, ambient, and operational stability of the device. This article was authored by Yuji Oluo, Kai Kai Liu, Liu Yang, and others.