LSPR peak shift of Ag Nanodot Arrays in Polymer Solar Cells by Tuning the Refractive Index of Surrounding Medium

Abstract

The application of localized surface plasmon resonance (LSPR) phenomena is one way among the most effective strategies to enhance the performance of polymer solar cells (PSCs). LSPR effects allow metal nanoparticles to efficiently scatter light, which can dramatically increase light absorption in the active layer of PSCs. The resonant wavelength of plasmonic metal nanoparticles is determined by their composition, size, shape and the surrounding medium. Unlike previous reports investigating the influence of LSPR materials on PSC performance, we have approached the LSPR phenomenon from a physical perspective by examining the influence of the surrounding environment on LSPR properties. Uniform 10 nm Ag nano-arrays (Ag NAs) were synthesized via block copolymer micelle lithography (BCML) and utilized in inverted structure PSCs. The Ag NAs were incorporated into various electron transport layers (ETLs) with different refractive indices. The resonant wavelength of Ag NAs showed a significant red-shift as the refractive index of the surrounding medium increased, which was consistent with theoretical calculations of the plasmonic materials, taking damping constants, non-local response and coupling effects into account. These embedded Ag NAs were manipulated in this way to achieve optimal light scattering in PSC devices. When incorporated into PSC devices, power conversion efficiencies (PCEs) of up to 8.51% were realized using Ag NPs embedded in TiO2 ETLs, corresponding to a 12.5% enhancement in JSC compared to 7.55% PCE observed in control devices without Ag NAs.