Modifying Electrochemical Doping in Light-Emitting Electrochemical Cells With Gold Nanoparticles.

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.