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

Efficiently suppressing the external quantum efficiency (EQE) roll-off of perovskite light-emitting diodes (PeLEDs) urgently requires designing passivation electron transporting layers (ETLs) for intrinsically passivating perovskite surface defects toward next-generation illumination and display. Here, we molecularly designed the inherent passivation ETL B3PyPPM with a strong nucleophilic core-group to effectively passivate perovskite surface defects. Compared with ETL B3PyMPM, the B3PyPPM can theoretically form a tighter interaction with the perovskite surface and transfer more electrons to better passivate surface Pb2+ vacancies, leading to superior suppression of EQE roll-off in PeLEDs by reducing the trap-assisted nonradiative recombination. Experimentally, the B3PyPPM-based PeLED exhibits a higher EQE of 18.04%, greater luminance of 4.15 times, and a longer T50 of 5.38 times than B3PyMPM-based PeLEDs, evidently proving the superior EQE roll-off suppression of the stronger nucleophilic core-group-based ETL. Therefore, this work provides important guidance for rationally designing multifunctional ETLs to achieve high-performance and long-term stability in PeLEDs.