Two-photon lithography of Organic Semiconductor Nanowires

Description

Organic semiconductors have gained significant attention in electronics due to their tunable
electronic properties, solution processability, and compatibility with flexible substrates. Among them,
poly(3,4-ethylenedioxythiophene) (PEDOT) stands out for its high electrical conductivity,
environmental stability, and wide applicability in organic electronic devices [1]. Despite these
advantages, conventional methods for PEDOT fabrication, such as chemical and electrochemical
polymerization, lack the spatial resolution required for nanoelectronic applications. Overcoming this
limitation requires high-precision lithographic techniques capable of defining PEDOT structures at
the nanoscale while preserving its intrinsic electronic properties.
In turn, multiphoton lithography (MPL) has recommended itself as a powerful tool for high-resolution,
three dimensional nanopatterning [2]. Controlling two-photon absorption with low-energy visible or
near-infrared femtosecond laser pulses prevents damage to sensitive materials like organic
semiconductors or biomaterials. When combined with stimulated emission depletion (STED) inspired
lithography [3], which confines the effective excitation volume to its central voxel, it enables the
fabrication of structures with feature sizes below 40 nm [4].
In this study, we applied these lithographic techniques to the oxidative polymerization of EDOT. We
discovered that 7-diethylamino-3-thenoylcoumarin (DETC), a well-established photoinitiator in
STED-inspired radical photopolymerization, can also serve as a photosensitizer for EDOT oxidative
polymerization. Additionally, we explored velocity-dependent lithography modes for both two-photon
lithography (TPL) and STED lithography, and we discuss the possible physical and chemical
mechanisms governing the polymerization process.

Period	Feb 2025
Event title	10th Conference on Applications of Femtosecond Lasers in Materials Science
Event type	Conference
Location	5570 Mauterndorf, AustriaShow on map
Degree of Recognition	International