Strongly Anchored Dion–Jacobson Perovskite for Efficient Blue Light-Emitting Diodes

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