Effect of Plasmonic Ag Nanoparticles on the Performance of Inverted Perovskite Solar Cells

Recently, perovskite solar cells (PSCs) have attracted phenomenal research interest due to their potential as the next-generation photovoltaics. Despite rapid development in this field, further increasing their power conversion efficiency (PCE) remains a critical issue for the commercialization of PSCs. Herein, the application of Ag nanoparticle (NP) layers via vapor-phase deposition onto perovskite active layers is investigated. The formation of unique, crescent-shaped Ag NPs is confirmed by scanning electron microscopy (SEM), which shows that the NPs self-assemble along the grain boundaries of perovskite, leading to their unique shape. The PCE for devices incorporating an optimized size of Ag NPs of 79 +/- 6 nm increase from 11.63% to 13.46% with an improvement factor of 15.74%. The increase in PCE is can be attributed to an increase in short-circuit current density (J(sc)) that is assigned to an increase in optical path length and absorption. NPs exhibit the ability to increase the optical path length of photons in the device due to the near-field and far-field enhancement (plasmonic scattering) and consequently may act to improve the photon-to-electron conversion efficiency (Delta IPCE) and PCE of PSCs. Moreover, ultraviolet photoelectron spectroscopy reveals a decrease in hole injection barrier (phi(h)), which also contributes to enhanced performance.