Polymer-capped copper nanoparticles trigger plasmonic field for improving performance of perovskite solar cells

Plasmonic nanostructures are often incorporated into perovskite solar cells (PeSCs) to achieve high power conversion efficiencies (PCEs) while using thin perovskite films and/or minimum amount of photoactive materials. Most plasmonic nanostructures, however, are based on noble metals, including gold and silver. High material cost somehow limits commercial applications in these cost-effective solar modules. In this work, we use copper (Cu), which is a more abundant and low-cost element, to prepare plasmonic nanoparticles (NPs); they also exhibit well plasmonic properties in the visible wavelength region. To overcome the instability of the Cu NPs, the NPs are further capped with polyvinylpyrrolidone (PVP) to avoid oxidation under ordinary ambient conditions. After the PVP-capped Cu NPs are incorporated into PeSCs, the devices exhibit improved PCEs under illumination at 1 sun; we attribute the device enhancement to local plasmonic field enhancement induced by the Cu NPs. Additionally, the PeSCs prepared with polymer-capped Cu NPs possess reasonable stability. We anticipate that the results in this study might open up new opportunities for fabricating plasmon-enhancing solar modules using cost-effective Cu nanostructures. [Display omitted] •Cu nanoparticles are readily oxidized and are not stable.•The Cu nanoparticles are protected by capping with polymers.•The efficiency of the perovskite solar cells was improved after Cu nanoparticles are incorporated.•The improved efficiency is attributed to the localized surface plasmon resonance of the Cu nanoparticles.•The device stability is not affected after the Cu nanoparticles are employed in the perovskite devices.