From Traps to Transport: Modulating Interfacial Carrier Dynamics in Perovskite LEDs by Additive Passivation

This study explores the impact of interfacial carrier dynamics on the performance of methylammonium lead bromide (CH3NH3PbBr3)-based perovskite light-emitting diodes (PeLEDs), focusing on mitigating trap states and ion migration through defect passivation. Carrier dynamics refers to the movement, recombination, and trapping of charge carriers (electrons and holes) within the material, directly affecting the efficiency of charge injection, transport, and radiative recombination. In PeLEDs, poor carrier dynamics, often caused by trap states and ion migration, can lead to nonradiative recombination, reducing device efficiency and stability. Using admittance spectroscopy, we analyze the influence of trap states on charge injection and recombination processes. Capacitance–voltage and frequency-response analyses indicate that passivation strategies improve interfacial properties by reducing ionic double-layer formation and improving dipolar polarization. The 3% choline chloride (Ch.Cl) passivated PeLED demonstrated optimal performance owing to improved carrier dynamics, defined by more efficient charge recombination, higher carrier mobility, and reduced nonradiative losses. Our findings reveal that reducing trap states and controlling ion migration significantly improve charge transport, minimize charge accumulation, and enhance the balanced charge injection behavior in PeLEDs. These insights into interfacial carrier dynamics offer a promising pathway for optimizing the performance of perovskite-based optoelectronic devices.