Molecularly Designing a Passivation ETL to Suppress EQE Roll-off of PeLEDs

Efficientlysuppressing the external quantum efficiency (EQE) roll-offof perovskite light-emitting diodes (PeLEDs) urgently requires designingpassivation electron transporting layers (ETLs) for intrinsicallypassivating perovskite surface defects toward next-generation illuminationand display. Here, we molecularly designed the inherent passivationETL B3PyPPM with a strong nucleophilic core-group to effectively passivateperovskite surface defects. Compared with ETL B3PyMPM, the B3PyPPMcan theoretically form a tighter interaction with the perovskite surfaceand transfer more electrons to better passivate surface Pb2+ vacancies, leading to superior suppression of EQE roll-off in PeLEDsby reducing the trap-assisted nonradiative recombination. Experimentally,the B3PyPPM-based PeLED exhibits a higher EQE of 18.04%, greater luminanceof 4.15 times, and a longer T (50) of 5.38times than B3PyMPM-based PeLEDs, evidently proving the superior EQEroll-off suppression of the stronger nucleophilic core-group-basedETL. Therefore, this work provides important guidance for rationallydesigning multifunctional ETLs to achieve high-performance and long-termstability in PeLEDs.