  Photo-bolometric effect is critically important in optoelectronic structures
and devices employing metallic electrodes with nanoscale features due to
heating caused by the plasmonic field enhancement. One peculiar case is
individual silver nanowires (Ag NWs) and their networks. Ag NW-networks exhibit
excellent thermal, electrical, and mechanical properties, providing a simple
yet reliable alternative to common flexible transparent electrode materials
used in optoelectronic devices. To date there have been no reports on the
photoresponse of Ag NWs. In this work, we show that a single Ag NW and a
network of such Ag NWs possess a significant, intrinsic photoresponse thanks to
the photo-bolometric effect, as directly observed and measured using scanning
photocurrent microscopy. Surface plasmon polaritons (SPP) created at the
contact metals or plasmons created at the nanowire-metal structures cause
heating at the junctions where a plasmonic field enhancement is possible. The
local heating of the Ag NWs results in negative photoconductance due to the
bolometric effect. Here an open-circuit response due to the plasmon-enhanced
Seebeck effect was recorded at the NW-metal contact junctions. The SPP-assisted
bolometric effect is found to be further enhanced by decorating the Ag NWs with
Ag nanoparticles. These observations are relevant to the use of metallic
nanowires in plasmonic applications in particular and in optoelectronics in
general. Our findings may pave the path for plasmonics enabled sensing without
a spectroscopic detection.
