Efficient and Ultraviolet-Durable Nonfullerene Organic Solar Cells: From Interfacial Passivation and Microstructural Modification Perspectives

Ultraviolet (UV)-durable organic solar cells (OSCs) are realized by incorporating a CdSe@ZnS quantum dots (QDs)-modified PEDOT:PSS hole extraction layer (HEL). The use of the CdSe@ZnS QDs-modified PEDOT:PSS HEL has an obvious improvement in UV-durability of OSCs. A more than 50% reduction in the power conversion efficiency (PCE) is observed for a (PM6:Y6)-based control OSC with a PEDOT:PSS HEL, under the 1000 min accelerated UV (365 nm, 16 W) aging test. Whereas a much reduced reduction of 35% in PCE is observed for the OSCs with a CdSe@ZnS QDs-modified PEDOT:PSS HEL, under the same accelerated UV aging test condition. Results reveal that the Coulombic attraction between the PEDOT units and PSS chains in the PEDOT:PSS layer is disturbed due to the interaction between hydroxyl ligands of the CdSe@ZnS QDs and PSS through hydrogen bond, leading to an increase in the electric conductivity in PEDOT:PSS layer through transforming PEDOT quinoid structure to expanded-coil structure. The use of the CdSe@ZnS QDs-modified PEDOT:PSS HEL also favors the efficient operation of the nonfullerene acceptor (NFA)-based OSCs through maintaining a high built-in potential across the bulk heterojunction. The results demonstrate the importance of the interface engineering to alleviate UV light-induced degradation processes of NFA-based OSCs.