Large perovskite grain's crystal synthesis for enhanced solar cells efficiency

Background: The perovskite grain structure greatly affects carrier transport characteristics, interfacial charge transfer dynamics, and phase stability where larger grain structures assist efficient interfacial charge transfer, reduce defect-limited transport, and enhance phase stability in the perovskite solar cell device, leading to effective energy conversion. Methods: We introduce a simple yet effective method to achieve a quasi-continuous crystal grain of FAPbI₃ perovskite by using an all-dynamics spin-coating technique during film fabrication process. Significant findings: The resulting quasi-continuous crystal grain sample features an exceptionally smooth surface morphology, an important attribute that promotes energetic interfacial charge transfer activities and enhances overall performance. Perovskite solar cells with an active area of 0.1 cm² fabricated using this approach exhibited remarkable power conversion efficiency of 22.8 %, with corresponding open-circuit voltage (V_oc), short-circuit current density (J_sc), and fill factor (FF) values of 1.16 V, 24.7 mA/cm², and 79.22 %, respectively. This represents an important advancement compared to solar cells produced through conventional methods, which only achieved efficiency of 21.5 %. Photoluminescence and dark current analyses reveal that the quasi-continuous grain perovskite demonstrates a hot-state carrier lifetime that is 18 times longer (18.45 ns) and lower electronic trap density than the reference device, thereby enabling a highly active photovoltaic process.