Modulating Perovskite Film Crystallization with Nipecotic Acid for High‐Performance Perovskite Solar Cells

Abstract The fabrication of high‐quality perovskite films plays a pivotal role in enhancing the power conversion efficiency (PCE) of perovskite solar cells (PSCs). This enhancement can be achieved by modulating the crystallization kinetics of the perovskite film. In this paper, nipecotic acid (NA) is employed as an additive to regulate the crystallization process to mitigate defect formation within the perovskite film. The mechanism is corroborated through in situ ultraviolet/visible (UV/Vis) absorption and photoluminescence (PL) measurements. Furthermore, NA facilitates the modulation of perovskite crystal orientation, as verified by grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) and X‐ray diffraction (XRD) analyses. Utilizing the NA additive, perovskite films exhibiting superior quality and reduced defect density are successfully fabricated. A champion device achieves a PCE of 24.76%. Remarkably, this device retains 94.04% of its initial PCE after 960 h of storage under ambient conditions (25 °C, 25% relative humidity, RH), demonstrating exceptional environmental stability.