The main objective of TransFlexTeg is to develop an innovative large area distributed sensor network integrating transparent thin film thermoelectric devices and sensors for multifunctional smart windows and flexible high impact volume applications. Different breakthrough concepts will be developed: 1) large area high performance transparent thermoelectric thin films deposited on flexible substrates for thermal energy harvesting; 2) low cost high throughput thin film thermal sensors for thermal mapping and gesture sensing; 3) flexible smart windows and walls with energy harvesting, environmental sensing and wireless communication functionalities. This technology aims to demonstrate the functionalities of a smart window able to measure air quality and environmental parameters such as temperature, sun radiation and humidity. The data is automatically collected and can be utilized for controlling heating, cooling and ventilation systems of indoors. Active radio interface enables long range communication and long term data collection with WiFi or a similar base station. The proposed concept of smart windows replaces several conventional sensors with a distributed sensor network that is integrated invisibly into windows. In addition to the power generated from the thermal energy harvesting, the thermoelectric elements (TE) are also used as temperature sensors that, while being distributed over large area, enable thermal mapping of the area instead of just one or a few values measured from particular points. This smart window can be produced on glass. The active layer itself can be flexible glass layer or polymer sheet, which will significantly broaden the field of applications and improve business opportunities. Both can be manufactured in batch, or in Roll to Roll Atomic Layer Deposition (R2R ALD) process. High environmental impact is expected with savings of more than 25% of the electrical usage of residential homes and office buildings.

The interaction of light with wavelength-sized photonic nanostructures is highly promising for light management applied to thin-film photovoltaics. Several light trapping effects come into play in the wave optics regime of such structures that crucially depend on the parameters of the photonic and absorbing elements. Thus, multi-parameter optimizations employing exact numerical models, as performed in this work, are essential to determine the maximum photocurrent enhancement that can be produced in solar cells.

Generalized spheroidal geometries and high-index dielectric materials are considered here to model the design of the optical elements providing broadband absorption enhancement in planar silicon solar cells. The physical mechanisms responsible for such enhancement are schematized in a spectral diagram, providing a deeper understanding of the advantageous characteristics of the optimized geometries. The best structures, composed of TiO2 half-spheroids patterned on the cells' top surface, yield two times higher photocurrent (up to 32.5 mA/cm2 in 1.5 µm thick silicon layer) than the same devices without photonic schemes.

These results set the state-of-the-art closer to the theoretical Lambertian limit. In addition, the considered light trapping designs are not affected by the traditional compromise between absorption enhancement versus current degradation by recombination, which is a key technological advantage.

Silver (Ag) and tin (Sn) nanoparticles (NPs) were deposited by thermal evaporation onto heated glass substrates with a good control of size, shape and surface coverage. This process has the advantage of allowing the fabrication of thin-film solar cells with incorporated NPs without vacuum break, since it does not require chemical processes or post-deposition annealing. The X-ray diffraction, TEM and SEM properties are correlated with optical measurements and amorphous silicon hydrogenated (a-Si:H) films deposited on top of both types of NPs show enhanced absorbance in the near-infrared. The results are interpreted with electromagnetic modelling performed with Mie theory. A broad emission in the near-infrared region is considerably increased after covering the Ag nanoparticles with an a-Si:H layer. Such effect may be of interest for possible down-conversion mechanisms in novel photovoltaic devices.