Highly efficient dual-plasmon polymer solar cell incorporating Au@SiO₂ core-shell nanorods and Ag nanoparticles

Generally, metallic nanoparticles (NPs) are widely employed in polymer solar cells (PSCs) to enhance power conversion efficiency (PCE) via the localized surface plasmon resonance (LSPR) effect. Herein, a significant performance enhancement is demonstrated in inverted PSCs by incorporating two kinds of metallic NPs on the rear side of photoactive layer. The Au nanorods (NRs) capped with ∼2 nm ultrathin SiO₂ shells, with plasmonic absorption peaks of 520 nm for the transverse axis and 615 nm for the longitudinal axis (in deionized water), and 1 nm-ultrathin Ag NPs with an absorption peak of 517 nm, are in sequence spin-coated on a photoactive layer and thermally evaporated onto MoO₃. To the best of our knowledge, this is the first time that Au NRs are directly spin-coated on a photoactive layer. The dual-plasmon device exhibits an improved short-circuit current density (J_SC) of 10.36 mA cm^-2 and an increased fill factor (FF) of 0.64, generating a PCE of 4.11% with a ∼30% enhancement factor compared with that of the reference device. The enhancement is attributed to the light absorption improvement in the photoactive layer over a wide wavelength range of 500-650 nm, induced by the LSPR of Au@SiO₂ NRs and Ag NPs. In addition to the excitation of the LSPR effect, the incorporation of Ag NPs into MoO₃ also contributes to the increase in FF value through enhancing the electric conductivity of MoO₃.