Research on UV-PSC led to the achievement of most of its objectives and technical goals, PCE value of over 10% and AVT of over 70%. More than 20 of low cost and transparent HMT based on small molecules have been developed and tested, especially for high band-gap materials, demonstrating the possibility to have high Voc (higher than 1.6 eV without any perovskite post treatment) and with quite remarkable efficiency.
The overall reported results represent the state of the art for NIR-DSSC regarding the possibility of having a transparent, nearly colourless device able to be easily integrated in building (i.e. up to 80% AVT and a CRI of 96 with colour coordinates approaching the white point). Moreover, the careful characterization performed on the working devices and the comparison between different families of materials highlighted the different issues (aggregation on the surface, short excited state lifetime, high Voc losses, low solubility, etc) that still prevent high efficiency and stability in wavelength selective dye-sensitized solar cells. This paves the way to further improvements. Finally, the gained knowledge on this large number of materials and in their interactions could also be exploited in other similar wavelength-selective applications.
The efficient, easy and scalable assembling protocol to combine the PSC and DSSC cells in a tandem stack was demonstrated. A PCE of 9.6% and AVT of 35% have been achieved in mechanically stacked tandem configuration and it will be the object of a scientific publication in the field of Building Integrated Photovoltaics (BIPV). Moreover an AVT of 55% has been obtained in a tandem configuration with the use of an ARC. The tandem technology also represents current state-of-the art in the field.
Non encapsulated devices based on near UV-MAPbBr3 revealed excellent stability under illumination at maximum power point condition and shelf-life stability over 6 months, both conditions without significant degradation in the cell performances.
The upscaled materials showed identical performance in the standard cells, while the synthetic procedures were even simplified and less costly in some cases. The device upscale lead to a decrease of the performance of the tandem but has no crucial impact on the visual point of view. An optimization of the deposition technique would certainly allow higher efficiencies. A 53% AVT has been reached on A4 tandem device, a value close to the 55% objective .
The detailed and integrated approach of SoA Life Cycle Analysis, quick cost analysis scan, benchmarking against other smart window systems and operational impact analysis of the IMPRESSIVE PV module has achieved sustainability results beyond the state-of-the art of results from simple LCA assessments. It was shown that the IMPRESSIVE PV window reveals substantial potential for sustainable BIPV via the synergy of renewable electricity generation by the transparent tandem DSSC – PSC module and energy savings due to reduced cooling demands through absorption of NIR by the DSSC. A quick cost analysis scan shows near-economic parity with commercial glazing systems.
