RESUMO
Solution processable organic tandem solar cells offer a promising approach to achieve cost-effective, lightweight and flexible photovoltaics. In order to further enhance the efficiency of optimized organic tandem cells, diffractive light-management nanostructures were designed for an optimal redistribution of the light as function of both wavelength and propagation angles in both sub-cells. As the fabrication of these optical structures is compatible with roll-to-roll production techniques such as hot-embossing or UV NIL imprinting, they present an optimal cost-effective solution for printed photovoltaics. Tandem cells with power conversion efficiencies of 8-10% were fabricated in the ambient atmosphere by doctor blade coating, selected to approximate the conditions during roll-to-roll manufacturing. Application of the light management structure onto an 8.7% efficient encapsulated tandem cell boosted the conversion efficiency of the cell to 9.5%.
RESUMO
A simple lamination process of the top electrode for perovskite solar cells is demonstrated. The laminate electrode consists of a transparent and conductive plastic/metal mesh substrate, coated with an adhesive mixture of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), PEDOT:PSS, and sorbitol. The laminate electrode showed a high degree of transparency of 85%. Best cell performance was achieved for laminate electrodes prepared with a sorbitol concentration of ~30 wt% per milliliter PEDOT:PSS dispersion, and using a pre-annealing temperature of 120°C for 10 min before lamination. Thereby, perovskite solar cells with stabilized power conversion efficiencies of (7.6 ± 1.0)% were obtained which corresponds to 80% of the reference devices with reflective opaque gold electrodes.
RESUMO
We present in-coupling gratings for improving the performance of thin film organic solar cells. The impact of the grating on the absorption in the active layer is modeled and explained using a standard cell architecture. An increase in absorption of 14.8% is predicted and is shown to be independent from the active material. The structure is then applied on blade-coated devices and yields an efficiency improvement of 12%. The angular behavior of the structures is measured showing superior performance for two dimensional gratings. By simulating the current generation for different angles and illumination conditions, we predict a total yearly increase of the generated current of 12% using an optimized grating. The fabrication of these structures, moreover, is compatible with roll-to-roll production techniques, thus making them an optimal solution for printed photovoltaics.
