Monoammonium Modified Dion‐Jacobson Quasi‐2D Perovskite for High Efficiency Pure‐Blue Light Emitting Diodes

Abstract Quasi‐2D perovskites exhibit impressive optoelectronic properties and hold significant promise for future light‐emitting devices. However, the efficiency of perovskite light‐emitting diodes (PeLEDs) is seriously limited by defect‐induced nonradiative recombination and imbalanced charge injection. Here, the defect states are passivated and charge injection balance is effectively improved by introducing the additive cyclohexanemethylammonium (CHMA) to bromide‐based Dion‐Jacobson (D‐J) structure quasi‐2D perovskite emission layer. CHMA participates in the crystallization of perovskite, leading to high quality film composed of compact and well‐contacted grains with enhanced hole transportation and less defects. As a result, the corresponding PeLEDs exhibit stable pure blue emission at 466 nm with a maximum external quantum efficiency (EQE) of 9.22%. According to current knowledge, this represents the highest EQE reported for pure‐blue PeLEDs based on quasi‐2D bromide perovskite thin films. These findings underscore the potential of quasi‐2D perovskites for advanced light‐emitting devices and pave the way for further advancements in PeLEDs.