Interfacial passivation with 2-aminopyridine for effective perovskite solar cells

Interface defect is one of the main factors that lead to non-radiative recombination of carriers at the interface and the decomposition of perovskites. This ultimately results in low efficiency and poor stability of perovskite solar cells (PSCs). Here, a passivated molecule called 2-Aminopyridine (2-APy) was proposed to reduce the defects of the interface between the perovskite and the hole transport layer. The results showed that the amino group in 2-aminopyridine can interact with the vacancy and free iodide ions on the surface of perovskite, thus passivating the defects at the interface and enhancing the hole transport capacity. As a result, 2-APy-modified PSCs exhibited inhibited non-radiative recombination, and the efficiency of PSCs increased to 21.46 %. The increase in the efficiency of PSCs is primarily seen in the rise of the open circuit voltage (VOC, from 1.12 to 1.15 V) and short circuit current (JSC, from 22.86 to 23.77 mA/cm2). This work demonstrates that pyridine is an effective group for passivating the defects between the perovskite layer and the hole transport layer.