Self‐Polymerization of Monomer and Induced Interactions with Perovskite for Highly Performed and Stable Perovskite Solar Cells

Abstract While there is promising achievement in terms of the power conversion efficiency (PCE) of perovskite solar cells (PSCs), long‐term stability has been considered the main obstacle for their practical application. In this work, the authors demonstrate the small monomer 2‐(dimethylamino) ethyl methacrylate (DMAEMA) with unsaturated carboxylic acid ester bond in the antisolvent for perovskite formation to improve the PCE and stability. The results show that DMAEMA is self‐polymerized and uniformly distributed in the film, contributing to the improved crystallinity of the perovskites. Equally important, it is found that there are newly established interactions of Pb 2+ and DMAEMA, and iodine and ternary amine between DMAEMA and perovskites, which improves the uniformity of the lead (II) iodide vertical distribution along with the films and thus phase stability, as well as largely decreases defects density in the film. Overall, the inverted PSCs with DMAEMA exhibit a open‐circuit voltage of 1.10 V, short‐circuit current of 23.86 mA cm −2 , fill factor of 0.82, and finally PCE reaches 21.52%. Meanwhile, the PSC stability is significantly improved due to the inhibition of the formation of iodine, reduction of the uncoordinated Pb 2+ , and suppression of phase segregation.