Plasmonic Transition via Interparticle Coupling of Au@Ag Core–Shell Nanostructures Sheathed in Double Hydrophilic Block Copolymer for High-Performance Polymer Solar Cell

We herein report a facile synthetic method for the preparation of gold-core, silver-shell nanoparticles (Au@Ag NPs) with tunable surface plasmon resonance (SPR) using the double hydrophilic block copolymer (DHBC), poly­(ethylene oxide)-<i>block</i>-poly­(acrylic acid) (PEO-<i>b</i>-PAA), as a template (Au@Ag@DHBC NPs), and the utilization of their unique optical properties in polymer solar cells (PSCs). It is demonstrated that two different functionalities of DHBC facilitate the formation of the respective Au-core and Ag-shell NPs. Interestingly, the isolated core–shell NPs in solution are found to be transformed into coupled NPs that ultimately exhibit the transition of intrinsic plasmonic properties to a wide range in the visible spectrum. Furthermore, plasmonic Au@Ag@DHBC NPs are effectively integrated into the active layer of PSCs, which remarkably enhance the power conversion efficiency (PCE) up to 9.0% (16% enhancement) because of the strong plasmonic effect of the coupled NPs and the thin polymeric layer surrounding the NPs. This study suggests the widespread potential application of DHBCs as a template for the synthesis of novel core–shell nanostructures. We anticipate that this approach will provide new means for creating a variety of plasmonic nanomaterials in various fields of optoelectronic devices.