Strongly Anchored\nDion–Jacobson Perovskite\nfor Efficient Blue Light-Emitting Diodes

Dion–Jacobson (DJ) perovskites are promising alternatives\nfor Ruddlesden–Popper (RP) perovskites to fabricate blue perovskite\nlight-emitting diodes (PeLEDs) due to their favorable structural and\ncharge properties. However, the relatively weak hydrogen bond between\nthe bridging diammonium group and perovskite poses huge challenges\nfor regulating crystallization and defect density, leading to an undesirable\nfilm quality and device performance. Herein, we report the successful\noptimization of DJ perovskite films by introducing a new type of cesium\noctafluoroadipate (CsOFAA) precursor, which could strongly anchor\nthe perovskite through coordination bonds and halogen–halogen\nbonds. Such an interaction between CsOFAA and perovskite significantly\nstabilizes the DJ perovskite structure and suppresses the nonradiative\nrecombination, leading to high-performance DJ perovskite films with\nefficient and stable blue emission. Accordingly, high external quantum\nefficiency values of 15.2%, 10.0%, and 8.3% are achieved for PeLEDs\nwith emission peaks at 490, 485, and 479 nm, respectively, representing\nthe most efficient blue DJ PeLEDs.