Dendritic PAMAM polymers for strong perovskite intergranular interaction enhancing power conversion efficiency and stability of perovskite solar cells

The modification of perovskite intergranular perovskite/perovskite interface plays a critical role for power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). In this work, polyamidoamine (PAMAM) dendrimers are utilized as the dendritic crystallization framework templating the perovskite-crystallizing process. The interactions at the perovskite intergranular interface are considerably strengthened at an ambient environment with dendritic PAMAMs crosslinking the perovskite grains. Consequently, the perovskite morphology is remarkably improved by suppressing the grain/grain-aggregate boundaries for the pinhole removal, which produces a compact, uniform and non-pinhole perovskite film. Finally, the strengthened interfacial interactions dramatically enhance the PCE value of unencapsulated PSCs about 42.6% at an ambient condition. Besides, the unencapsulated PAMAM-modified device can keep 73% of initial PCE value in 400 h while the control device decays to 5% of initial PCE value in 50 h. These results reveal that dendritic polymers might remarkably improve the PCE value and the stability of PSCs. This work provides a new molecular design guideline to effectively regulate the perovskite intergranular interfacial interactions.