This study presents a novel method for direct electron beam patterning of commercially available PEDOT:PSS, enabling high-resolution, sub-micron-scale nanostructures. The technique involves electron-beam induced solubility modulation, where unexposed regions of the conductive polymer are washed away in water, leaving only the patterned regions. The method allows for the fabrication of electrically switchable optical diffraction gratings with feature sizes down to 250 nm, an order of magnitude finer than previous direct write methods. The resulting structures maintain the conductivity, electrochemical, and optical properties of PEDOT:PSS, demonstrating their stability in aqueous environments. The method is simple, requiring only a single-step development in water, and is compatible with common conductivity-enhancing additives such as ethylene glycol. The study demonstrates the potential of this method for enabling a wide range of novel micro- and nano-scale optoelectronic devices. The fabricated diffraction gratings can be switched between "ON" and "OFF" states using CMOS-compatible voltages, achieving over 95% switching contrast. The method is also shown to be compatible with flexible substrates, opening up new possibilities for wearable and flexible electronics. The study highlights the potential of this technique for enabling the next generation of low-power, dynamic optoelectronic systems.This study presents a novel method for direct electron beam patterning of commercially available PEDOT:PSS, enabling high-resolution, sub-micron-scale nanostructures. The technique involves electron-beam induced solubility modulation, where unexposed regions of the conductive polymer are washed away in water, leaving only the patterned regions. The method allows for the fabrication of electrically switchable optical diffraction gratings with feature sizes down to 250 nm, an order of magnitude finer than previous direct write methods. The resulting structures maintain the conductivity, electrochemical, and optical properties of PEDOT:PSS, demonstrating their stability in aqueous environments. The method is simple, requiring only a single-step development in water, and is compatible with common conductivity-enhancing additives such as ethylene glycol. The study demonstrates the potential of this method for enabling a wide range of novel micro- and nano-scale optoelectronic devices. The fabricated diffraction gratings can be switched between "ON" and "OFF" states using CMOS-compatible voltages, achieving over 95% switching contrast. The method is also shown to be compatible with flexible substrates, opening up new possibilities for wearable and flexible electronics. The study highlights the potential of this technique for enabling the next generation of low-power, dynamic optoelectronic systems.