  Dual-phase time-projection chambers (TPCs) filled with noble elements are
used for particle detection, with many focusing on rare-event searches. These
detectors measure two signals: one from scintillation light, and another from
drifting ionized electrons. The DarkSide-20k design uses a transparent vessel
with external photodetectors. Electrodes, used to drift the electrons, are
located between the active medium and the photodetectors, requiring them to be
transparent to allow scintillation light to transmit through them. The
transparent electrode coating for DarkSide-20k is
poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS) or
Clevios. For rare-event search detectors, the fluorescence of materials that
are between the active volume and the photodetectors may lead to backgrounds in
the data. Since Clevios is a new material for TPC electrodes, its fluorescent
properties need to be characterized to understand their potential impact on
backgrounds. Previous studies have indicated that Clevios can fluoresce, with
maximal fluorescence produced using UV-excitation. Our study analyzes the
fluorescence of Clevios, under UV-excitation, using both time-resolved and
spectral techniques between 4 K and 300 K. We find that the fluorescence of
Clevios is negligible when compared to the fluorescence of common fluorescent
materials used in TPCs, such as 1,1,4,4-tetraphenyl-1,3-butadiene (TPB).
