Ionic Liquid‐Induced 1D Perovskite: Exploring 1D Perovskite Structure to 1D/3D Heterojunction‐Based Photovoltaics

Abstract The synergistic utilization of low‐dimensional perovskites with 3D perovskite architectures represents a pervasive approach for fabrication of high‐performance and enduring perovskite solar cells (PSCs). In this work, four distinct ionic liquids (ILs) with distinct cations, were introduced on the surface of 3D perovskite to induce the formation of 1D perovskite.Starting with the analysis of 1D/3D heterojunction structures, the assessment foucsed on the binding energies in four ILs‐induced 1D/3D heterojunctions, comparing electron cloud density within 1D/3D structures, and calculating the formation energies associated with iodine and lead defects within these four 1D/3D perovskite structures via DFT calculations. Furthermore, the time‐resolved grazing‐incidence wide‐angle X‐ray scattering technique, as employed in this study, offers real‐time insights into the phase‐transition occurring during the process of ILs coating and the formation of 1D/3D heterojunctions. The well‐designed and optimized 1D perovskite layer significantly reduces the residual lead iodide (PbI 2 ), modulates the work function of the perovskite, and passivates defects in the 3D perovskite, thereby reducing non‐radiative recombination and enhancing charge transport. With the assistance of 1D/3D hybrid films, we achieved an exceptional power conversion efficiency (PCE) of 24.75% in the generated PSCs with remarkable stability.