The effectiveness of the mesoporous TiO2 layer, which acts as an active n-type semiconductor layer in dye sensitized solar cells (DSSCs) was investigated by varying the AgVO3-doping. To optimize the meso-superstructure, the doping concentration was varied from 0% to 25% using experimentally validated simulations. Moreover, performance comparisons between experimentally fabricated DSSCs based on natural beetroot and the commonly used N719 dye were made. A 15%doping concentration was found optimum for our DSSC, which delivered an output power of 19.24 mW, 6.1% power conversion efficiency, as well as an open circuit voltage, Voc, of 0.5 V and a short circuit current, Isc, of 21 mA/cm 2 in diffused light conditions. Based on these performance results, we integrated our optimized DSSC in an underwater sensing unit as a light harvester.
Thanks to recent advancements in nanofabrication and 2 3D packaging, typical Internet of Things (IoT) devices can now be 3 wirelessly controlled using millimeter scale sensors known as 4 Internet of Tiny Things (IoT²) devices. Since these low power devices 5 may be exposed to low and indirect solar irradiation, we demonstrate 6 a novel meso-superstructured solar cell (MSSC) that allows low flux 7 light to be harvested from both its top and bottom sides. Our cell is 8 based on either a dye-sensitized solar cell (DSSC) or a perovskite 9 solar cell (PSC). The active layer in the proposed MSSCs was tuned 10 to allow semi-transparent behavior. Moreover, we developed an 11 experimentally validated model that enables optimization of the 12 active layer thickness for different semi-transparent MSSC 13 applications. In MSSCs, such optimization is necessary to balance 14 the trade-off between transparency and efficiency for various active 15 layer thicknesses. Fabricated DSSCs and PSCs cells were used to 16 validate the simulation results. The fabricated DSSC achieved a 17 harvesting ratio of 1:10 with a conversion efficiency of around 2% at 18 one Sun. We demonstrate that the optimum thickness of the 19 mesoporous TiO2 active layer in DSSCs was 800 nm, enabling a 20 maximum power density of 7 mW/cm 2 .
The results investigated in this work are toward the optimization of the photonic crystal structures in 1D and 2D scale. One-dimensional distributed Bragg reflectors (DBRs) have demonstrated substantial potential in various optoelectronic applications, due to the observed tunable optical band-gap. Herein, the use of DBRs in light trapping solar cells was simulated and validated, representing its effect as a back reflector structure. In terms of the layer thickness, material selection and number of layer, the optimized DBR structure was modeled and evaluated with respect to previously published numerical and experimental data. The proposed model is capable of designing photonic crystal structures with tunable band-gap varies from 400 nm to 700 nm while controlling the pass-band in both Visible and Near Infra-red regions. On the other hand, 2D grating structure has been simulated where the transmission spectra under various design dimensions have been investigated. Finally, thin film deposition is utilized for experimental validation to our proposed optical model.
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