Improvement of polypyrrole nanowire devices by plasmonic space charge generation: high photocurrent and wide spectral response by Ag nanoparticle decoration

In this study, improvement of the opto-electronic properties of non-single crystallized nanowire devices with space charges generated by localized surface plasmon resonance (LSPR) is demonstrated. The photocurrent and spectral response of single polypyrrole (PPy) nanowire (NW) devices are increased by electrostatically attached Ag nanoparticles (Ag NPs). The photocurrent density is remarkably improved, up to 25.3 times, by the Ag NP decoration onto the PPy NW (PPy$_{\mathrm{AgNPs}}$ NW) under blue light illumination. In addition, the PPy$_{\mathrm{AgNPs}}$ NW shows a photocurrent decay time twice that of PPy NW, as well as an improved spectral response of the photocurrent. The improved photocurrent efficiency, decay time, and spectral response resulted from the space charges generated by the LSPR of Ag NPs. Furthermore, the increasing exponent ($m)$ of the photocurrent ($J_{\mathrm{PC}}\sim V_{m})$ and finite-differential time domain (FDTD) simulation straightforwardly indicate relatively large plasmonic space charge generation.