Thermally evaporated Ag nanoparticle films for plasmonic enhancement in organic solar cells: effects of particle geometry

Abstract

We report on the simple fabrication of Ag NP films via thermal evaporation and subsequent annealing. The NPs are formed on indium tin oxide electrodes, coated with PEDOT:PSS and implemented into PCPDTBT:PC70BM solar cells. Scanning electron microscopy and atomic force microscopy are used to determine the size distributions and surface coverage of the NP film. We apply finite‐difference time‐domain techniques to model the optical properties of different nanoparticle films and compare this with the absorption properties of the organic active layer. The simulations demonstrate that the absorption and scattering efficiency of the particles are very sensitive to particle geometry. Solar cells prepared with window electrodes containing NP layers with less surface coverage, show a 14.8% improvement in efficiency. We discuss variations in the external quantum efficiency of the devices in terms of forward scattering and parasitic absorption losses induced by the NP layer. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)

Effect of Au nanoparticles on PCPDTBT:PC 71 BM device performance with fair comparisons

“…A similar peak around 400 nm can be seen in other reports such as Refs. , however, its ascription is not currently explained.…”

“…Many papers have suggested that the light scattering and the near field effect of nanoparticles have important roles in the enhanced device performance . Jung et al reported that the enhanced light scattering of Ag NPs was attributed to the efficiency enhancement.…”

“…A similar peak around 400 nm can be seen in other reports such as Refs. [13,14], however, its ascription is not currently explained. Table 1 showed characteristics of the devices that do or do not embed Au NPs.…”

Effective medium analysis of thermally evaporated Ag nanoparticle films for plasmonic enhancement in organic solar cell

“…If the sphere is elongated in the y-direction (resulting in a prolate spheroid), L increases and if the sphere is compressed in the y-direction (resulting in an oblate spheroid), L decreases. It is the difference in L that explains the red and blue shift in plasmon resonance of the oblate and the prolate spheroid NPs, respectively [11,30].…”

“…Generally, this experimental implementation requires more complicated processes and the plasmonic rear-side features are challenging as the processing of OSCs usually begins with the transparent electrode [9]. The third strategy is distributing MNPs in the hole/electron collection or exciton blocking layer between the active layer and the electrode, either by thermal evaporation [10][11][12][13][14] or solution-processing [15][16][17]. Consequently, the last strategy can potentially have the advantage of easy fabrication, combined with controlled distance from the active layer, which allows for taking advantage of both near and far field enhancement.…”