Femtosecond Direct Laser Writing of Conductive and Electrically Switchable PEDOT:PSS Optical Nanostructures

Microscale three-dimensional (3D)-printing, with its remarkable precision and ability to create complex structures, has transformed a wide range of applications, from micro-optics and photonics to endoscopy and quantum technologies. In these fields, miniaturization plays a crucial role in unlocking new capabilities. However, despite these advancements, most 3D-printed optical structures have remained static, lacking dynamic behavior and tunability. In this study, a novel approach is presented that combines direct laser writing with the electrically switchable optical properties of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS). This integration facilitates the creation of dynamic structures directly on 3D-printed objects, marking a significant step toward adaptive optical devices. The fabrication of electrically tunable structures is demonstrated via direct laser writing using PEDOT:PSS on indium tin oxide (ITO)-coated glass substrates, as well as beneath and atop static 3D-printed structures. It is found that electrical conductivity as well as the greyscale behavior of PEDOT:PSS remains intact after direct laser writing. The switching speed, durability, and gradual tunability of the material are explored upon complementary metal-oxide-semiconductor (CMOS)-compatible voltages ranging from -3 to +2 V. In the future, this advancement opens exciting possibilities in adaptive micro-optics, such as switchable apertures printed directly onto micro-optical lenses.