Macromers for Encapsulating Perovskite Photovoltaics and Achieving High Stability.

Perovskite solar cells (pero-SCs) are highly unstable even under trace water. Although blanket encapsulation (BE) strategy applied in industry can effectively block moisture invasion, the commercial ultraviolet-curable adhesives (UVCAs) for BE still trigger power conversion efficiency deterioration, and the degradation mechanism remains unknown. For the first time, we revealed the functions of commercial UVCAs in BE-processed pero-SCs, where the small-sized monomer easily permeates to perovskite surface, forming an insulating barrier to block charge extraction, while the high-polarity moiety can destroy perovskite lattice. To solve these problems, we carefully designed a macromer, named PIBA, by grafting two acrylate terminal groups on the highly gastight polyisobutylene and realized an increased molecular diameter as well as avoided high-polarity groups. The PIBA macromer can stabilize on pero-SCs and then sufficiently crosslink, forming a compact and stable network under ultraviolet light without sacrificing device performance during the BE process. The resultant BE devices show negligible efficiency loss after storage at 85% relative humidity for 2000 h. More importantly, these devices can even reach ISO 20653:2013 Degrees of protection IPX7 standard when immersed in one-meter-deep water. This BE strategy shows good universality in enhancing moisture stability of pero-SCs, irrespective of the perovskite composition or device structure. This article is protected by copyright. All rights reserved.