Synergistic Plasmonic Enhancement in PM6:Y6 Organic Solar Cells Using Hybrid Gold Nanostars and Gold Nanoparticles Embedded in the AZO Electron Transport Layer

Abstract

Organic solar cells (OSCs) offer unique advantages—including mechanical flexibility, lightweight design, and compatibility with low-temperature solution processing—yet their performance remains constrained by the intrinsically thin active layers required to circumvent the short exciton diffusion length. Here, we introduce an optical–plasmonic engineering strategy that embeds gold nanostars (AuNSs) and hybrid AuNS/gold nanoparticle (AuNP) ensembles into the Al-doped ZnO (AZO) electron transport layer to simultaneously amplify light absorption and enhance carrier generation in PM6:Y6 OSCs. The multi-branched architecture of AuNSs enables intense tip-enhanced localized surface plasmon resonance (LSPR), while the hybrid AuNS/AuNP system yields broadband plasmonic coupling and improved scattering across the visible region. As a result, OSCs incorporating 10 vol% AuNSs and 5 vol% AuNS/AuNP mixtures achieve power conversion efficiencies of 11.66% and 12.36%, respectively, representing substantial improvements over the reference device. Finite-difference time-domain (FDTD) simulations reveal that plasmonic hybridization in the mixed-shape ensemble produces strongly localized near-field intensification and broadened optical cross-sections, whereas excessive particle loading induces detrimental field localization that suppresses charge transport. This work demonstrates a morphology-insensitive, spectrally tunable plasmonic strategy for advancing high-performance OSCs and highlights the promise of engineered nanoparticle synergies in next-generation photovoltaic systems.