Defect Passivation in Quasi-2D Perovskite Light-Emitting Diodes by an Ibuprofen Additive

It is well known that the inferior film morphology and the excessive surface/interface defect states are two obstacles to achieving high electroluminescence performance of quasi-2D perovskite light-emitting diodes (PeLEDs). To solve these problems, ibuprofen was introduced as an additive in the quasi-2D perovskite emitting layer. More efficient photoluminescence is demonstrated. Further, optimized quasi-2D PeLEDs with a current efficiency of 55.93 cd/A are confirmed and 5.7-fold enhancement in device stability is obtained. The physical mechanism of the remarkable improvement is investigated by kinds of measurements. Three aspects should be counted into it. First, the introduction of ibuprofen can passivate defects, thus making the quasi-2D perovskite emitting layer more dense and homogeneous. The reason should be that the C═O functional group and C═C bond in the benzene ring in ibuprofen can coordinate the unsaturated Pb²⁺ perovskite emitting layer. Meanwhile, the related exciton harvesting process is investigated. The proportion of the crystalline phases (small n and large n phase) can be tuned to benefit the energy funneling process. Finally, the analysis of the current density and voltage curves of the hole-dominated devices and the electron-dominated devices is conducted by utilizing the space charge-limited current (SCLC) methods.