Diverse Metal Ion Polyelectrolytes as Hole Transport Layers for Quasi-2D Perovskite Light-Emitting Diodes

This work investigates the role of metal ion-doped (Cs⁺, Ni²⁺, and Cu²⁺) PEDOT:PSS films as hole transport layers (HTLs) in quasi-2D perovskite light-emitting diodes (PeLEDs). These HTLs lead to enhanced device performance through reduced defect density, improved hole mobility, and prolonged photoluminescence lifetime. X-ray diffraction (XRD) reveals structural modifications in CsPbBr₃ films, with enhanced crystallinity resulting from the elimination of excess long-chain cations. Morphological analyses using scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrate the influence of metal doping on surface coverage and nanoscale roughness. Time-resolved photoluminescence (TR-PL) analysis confirms reduced nonradiative recombination, supporting improved film quality. Devices with Ni:PEDOT:PSS exhibit the highest external quantum efficiency, while Cs:PEDOT:PSS and Cu:PEDOT:PSS offer enhanced stability, achieving significantly longer operational lifetimes. These findings highlight the potential of metal-doped PEDOT:PSS in optimizing the structural, optical, and electrical properties of perovskite materials, paving the way for more stable and efficient PeLEDs.