Modifying Electrochemical Doping in Light‐Emitting Electrochemical Cells With Gold Nanoparticles

ABSTRACT Electrochemical doping enables dynamic control of organic semiconductors and underpins technologies such as electrochemical transistors, energy‐storage, bioelectronic, and light‐emitting devices. It is typically governed by the active‐material composition or the applied voltage. Here, we show that Au nanoparticles (Au‐NPs) incorporated at an electrode interface provide an additional control parameter. Using light‐emitting electrochemical cells (LECs) as a model system, we demonstrate that Au‐NPs at the anodic interface reshape the electrochemically formed p‐n junction, which defines the emission zone. Non‐capped Au‐NPs shift the emission zone away from the anode, whereas citrate‐capped Au‐NPs shift it toward the anode. By selecting the appropriate Au‐NP type, we reposition the emission zone closer to a region of constructive optical interference, leading to a strong increase in LEC emission efficiency. These results establish interfacial Au‐NPs as a strategy to modulate the spatial profile of electrochemical doping and tune the performance of organic electronic devices.