Effect of size and morphology of Au nanostructures on boosting performance of organic photovoltaic devices: Plasmonic and non-plasmonic effects

•We fabricated OPVs containing various Au nanostructures mixed with hole-collecting layer.•Plasmonic effect was induced by visible light absorption of Au nanostructures.•EQE enhancement at dissimilar wavelengths of visible light can be attributed to the modulated plasmonic absorption of Au.•Scattering of UV light induced by Au can come into play in enhancing light-harvesting efficiency.•The optical response pattern of OPVs can be modulated by size and shape-control of the Au nanostructures.

We fabricated organic photovoltaic (OPV) devices containing various Au nanostructures mixed with hole-collecting buffer layer. The presence of the Au nanostructures results in enhancement of the external quantum efficiencies (EQE) at dissimilar wavelengths of visible light, which can be attributed to the modulated plasmonic absorption frequency of the Au nanostructures. In addition to this plasmonic effect induced by visible light absorption, an increase in the EQE was also found upon UV excitation, which can be attributed to scattering effects induced by Au particles. The optical response pattern of organic photovoltaic devices can be modulated in a wide range of visible and UV wavelengths, by controlling sizes and shapes of the Au nanostructures.