Nanoparticles and nanostructures with plasmonic resonances are currently being employed to enhance the efficiency of solar cells. <sup>1-3</sup> Ag stripe arrays have been shown theoretically to enhance the short-circuit current of thin silicon layers. <sup>4</sup> Monolayers of Ag nanoparticles with diameter d < 300 nm have shown strong plasmonic resonances when coated in thin polymer layers with thicknesses < d.<sup>5</sup> We study experimentally the diffuse vs. specular scattering from monolayer arrays of Ag nanoparticles (spheres and prisms with diameters in the range 50 – 300 nm) coated onto the front side of thin (100 nm < t < 500 nm) silicon films deposited on glass and flexible polymer substrates, the latter originating in a roll-to-roll manufacturing process. Ag nanoparticles are held in place and aggregation is prevented with a polymer overcoat. We observe interesting wavelength shifts between maxima in specular and diffuse scattering that depend on particle size and shape, indicating that the nanoparticles substantially modify the scattering into the thin silicon film.
Organolead halide perovskites are attracting considerable attention for applications in high performance and flexible hybrid photovoltaic devices. Low temperature solution-processed flexible hybrid solar cells with CH<sub>3</sub>NH<sub>3</sub>PbI<sub>2</sub>Cl, using [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) and Poly[(9,9-di-n-octylfluorenyl-2,7-diyl)-alt- (benzo[2,1,3]thiadiazol-4,8-diyl)] (F8BT) as electron transport materials were fabricated on ITO coated plastic substrates in planar configuration. Poly(3,4-ethylenedioxythiophene):polystyrene sulfonate was employed as the electron blocking layer. Under standard AM 1.5G solar irradiation, these flexible solar cells yielded power conversion efficiencies of 5.14% and 7.05% with the electron transporting materials PCBM and F8BT, respectively.