Plasmonic nanoparticle incorporation into inverted hybrid organic–inorganic solar cells

Abstract

To enhance solar harvesting in hybrid organic–inorganic photovoltaic devices we positioned plasmonic gold nanostructures in titania-conjugated polymer devices. Two plasmonic structures were judiciously designed and studied. In the first, agglomerates of gold nanoparticles, ∼150nm in diameter, were positioned as scattering clusters at the active layer/ITO electrode interface. In the second approach, 5nm isolated Au particles were suspended inside the hybrid active layer to induce localized plasmonic field enhancement. The location of the particles, size and distribution in the film was confirmed using scanning and transmission electron microscopy and X-ray scattering. The optical absorption measurements confirmed that both plasmonic structures enhance light harvesting, and photovoltaic devices utilizing each of the approaches showed improved photocurrent generation. Finite difference time domain simulations have corroborated that scattering-based and near-field absorption enhancements occur in the active layer, in good agreement with the measured absorption. Finally, combining both approaches to fabricate a hybrid photovoltaic device with both plasmonic nanostructures, i.e. Au NPs both in and on the active layer, resulted in a twofold increase in photocurrent generation.