Reduced Efficiency Roll‐Off and Improved Stability of Mixed 2D/3D Perovskite Light Emitting Diodes by Balancing Charge Injection

TLDR

Perovskite light‑emitting diodes have achieved external quantum efficiencies above 21%, yet their efficiency declines at higher current densities and lifetimes remain only a few hours. The study aims to investigate the mechanisms causing EQE roll‑off and instability in PeLEDs. The authors use a mixed 2D/3D perovskite emissive layer that confines excitons and shapes electron/hole distributions, and propose a model explaining the resulting performance gains. Tuning electron/hole transport balance in the mixed 2D/3D layer yields a nearly flat EQE from 0.1 to 200 mA cm⁻², reduces roll‑off up to 250 mA cm⁻², and extends half‑lifetime to ~47 h at 10 mA cm⁻².

Abstract

Abstract Perovskite light emitting diodes (PeLEDs) have reached external quantum efficiencies (EQEs) over 21%. Their EQE, however, drops at increasing current densities ( J ) and their lifetime is still limited to just a few hours. The mechanisms leading to EQE roll‐off and device instability require thorough investigation. Here, improvement in EQE, EQE roll‐off, and lifetime of PeLEDs is demonstrated by tuning the balance of electron/hole transport into a mixed 2D/3D perovskite emissive layer. The mixed 2D/3D perovskite layer induces exciton confinement and beneficially influences the electron/hole distribution inside the perovskite layer. By tuning the electron injection to match the hole injection in such active layer, a nearly flat EQE for J = 0.1–200 mA cm −2 , a reduced EQE roll‐off until J = 250 mA cm −2 , and a half‐lifetime of ≈47 h at J = 10 mA cm −2 is reached. A model is also proposed to explain these improvements that account for the spatial electron/hole distributions.