Heterocyclic Diammonium Dion‐Jacobson Perovskite Blue Light‐Emitting Diodes with Nonshift Emission Peak Under High Bias Voltage

Abstract The emission peak shift caused by ion motion, especially under high bias voltage, is an obstacle to the development of blue perovskite light‐emitting diodes (PeLEDs). In this work, 3‐Aminopiperidine dihydrochloride (3AP) to construct heterocyclic dication Dion‐Jacobson (DJ) PeLEDs is introduced, and found that 3AP incorporation can retard the halide segregation and chloride loss, leading to the improvement of the emission spectral stability. By increasing the amount of 3AP (DJ phase), emission centers can be tuned from green to blue but the excitonic peak abnormally disappears, indicative of exciton delocalization. Photoluminescence quantum yield (PLQY) and ultrafast spectroscopy indicated that the introduction of 3AP can passivate defects and control the exciton delocalization to facilitate interlayer charge transfer. The external quantum efficiencies (EQE) of the obtained green (513 nm), sky blue (488 nm), and blue (478 nm) PeLEDs reached 3.0%, 7.1%, and 4.8%, respectively, and the maximum luminance is 10956, 1093 and 782 cd m −2 , respectively. Most importantly, under high operating voltages from 3 to 10 V, the PeLEDs delivered outstanding spectral stability free of peak shift.