I consider that all the achievements reported in the previous section have important implications for the state-of-the-art at different and multiple levels, as the work carried out covered different topics. Likely, the most important progress is in fact at the center of the research topic of the No-LIMIT project: the synthesis, analysis and further application in photovoltaic devices of the interaction between HP and QDs. We reported that HP with embedded PbS QDs can produce devices with higher efficiency, but also stability. Our initial hypothesis was eventually proven correct and we have been able to take advantage of it to increase the efficiency of the devices. In addition, we have observed very important side effects. We have observed an enormous increase of the solar cell long term stability. Interestingly, in the important halide perovskite FAPbI3 we observe that the addition of PbS quantum dramatically extends the crystalline phase stability, stabilizing the metastable perovskite back phase. In addition, the temperature for the formation of FAPbI3 black phase decreases significantly from 170ºC to 85ºC when QDs are added, with important implication from the industrial point of view as could produce important energy saving during the fabrication process. Very importantly we have also unveil the physical processes allowing these multibenefical effects. It is not due to a single cause but to a synergistic interaction of different processes, see Fig. 1, strain, the presence of interfaces and the chemical bonding between perovskite and PbS QDs that stabilizes more significantly the black phase. All these effects together enhance dramatically the stability of the black phase. In addition the presence of Pb-O chemical bonds, when devices are fabricated in air atmosphere, blocks the propagation of the yellow phase. These results can have important implication beyond the materials and devices directly studied in this project.
Moreover the new methodologies developed, the equivalent circuit for impedance spectroscopy analysis and the high-throughput outdoors analysis also introduced a significant evolution in the state-of-the-art for impedance and outdoors characterization, helping the community to a better understanding of PSC devices in a broad range of configurations and working conditions. In conclusion, this project has shown the enormous potential of synergetic interaction of halide perovskite with other systems as materials taking advantage of the its soft nature clearly highlighted in this project in the interaction perovskite/quantum dot. At the same time specific characterization methodologies considering the especial properties of halide perovskites will allow a faster and more precise and understandable analysis of these materials and devices.
