Toward efficient, moisture-resistant and lead-leakproofness perovskite solar cells: Coordination-driven reconstructing homogeneous amorphous perovskitoid/crystalline perovskite photoabsorber

Organic-inorganic hailed perovskites have emerged as thrilling materials for photovoltaic devices owing to their specific combination of the easy-processed, superb charge mobility and strong light absorption. However, it is still challenging to simultaneously obtain efficient and stable perovskite solar cells (PSCs) because of the defect-induced ions migration and the inherent low moisture tolerance. Herein, we report a perovskite photoabsorber with a novel alkylated amorphous perovskitoid/crystalline perovskite (a-PVKD/c-PVK) structure fabricated through a facile coordination-driven self-assembling process. We systematically elucidated the dissolution-reconstruction mechanisms of this a-PVKD/c-PVK structure and figured out the chemical interaction between the a-PVKD and the c-PVK. This judicious a-PVKD/c-PVK structure significantly hinders the moisture invasion, blocks the ion migration, and suppresses the nonradiative recombination, enabling to obtain a high efficiency over 21.5 % for MAPbI3 solar cells. The unencapsulated a-PVKD/c-PVK cell maintains more than 94 % of the initial efficiency after aging for 30 days (∼55% humidity), exhibiting a high long-term stability. Our work not only provides an effective way to synthesize novel perovskitoid materials, but also indicates the significant potential of a-PVKD/c-PVK architecture in PSCs.