Periodic Reporting for period 4 - No-LIMIT (Boosting Photovoltaic Performance by the Synergistic Interaction of Halide Perovskites and Semiconductor Quantum Dots)
Reporting period: 2022-03-01 to 2023-02-28
Solar energy is not only a clean source of renewable energy but also the most abundant one. In the last years the plummeting of the cost of Si solar modules has changed the traditional scenario. Greater competitiveness should emerge from a higher efficiency. However, as already stated, single absorber solar cells are very close to their theoretical maximum. Intermediate bandgap Solar Cells (IBSCs) can move theoretically the photoconversion efficiencies even significantly higher. No-LIMIT proposes to take advantage of the soft nature of HPs to incorporate embedded semiconductor quantum dots (QDs) using the synergistic interaction to enhance performance. It will be needed to determine and model the unique properties of HP and QD interaction from theoretical and experimental points of view. We will tailor the properties of HP, by the appropriated choice of constituent elements of HP with general formula ABX3, and QDs, by the choice of adequate compound and size, to optimize the different bandgap and band alignment. Preparation of QD layers embedded in HP matrix with low non-radiative recombination, high long wavelength absorption and excellent transport properties will allow the development of efficient solar cells. The results will undoubtedly produce a great scientific impact in the photovoltaic field. There is a global interest in the potentiality of halide perovskites, and No-LIMIT will help to ensure a leading role of Europe in this research field. However, No-LIMIT also foresees the transition from lab to industry. It is worth to highlight that collateral benefits for the development of other applications will take benefit from this research. The characterization of these materials will allow being transferred to other systems and materials.
No-LIMIT is an ambitious project which aims to take advantage of the interaction between HPs and QDs to enhance the photoconversion performance of halide perovskite solar cells (PSCs). To achieve this ambitious goal we have addressed the synthesis of HPs in different configurations, their study and characterization, as well as modeling atomically the system with first principles getting fundamental knowledge beyond the current state-of-the-art. The major achievements have been published in 68 papers.
One of the aspects analyzed in No-LIMIT was the preparation of benchmark PSCs with 20% efficiency. Properties of perovskite solar cells can be also managed by the addition of innovative conjugated bulky cations as anilinium or dipropylammonium.
Facing the future commercialization of this technology we have analyzed by life cycle assessments of alternative configurations, using carbon contacts, and fabrication processes as the fast infrared annealing and comparing with other photovoltaic technologies.
The use of Pb-free system was also studied for both thin films and QDs preparing Sn-PSCs with record stability.
We have developed a new methodology for the characterization of PSCs outdoors.
The working principles of PSCs have been investigated in detail by impedance spectroscopy (IS) obtaining the equivalent circuit for PSCs.
The first objective of the No-LIMIT project is the determination and modelling of the unique properties of halide perovskite and semiconductor QDs from theoretical and experimental points of view. We consider that this objective have accomplished. We have observed that HP films with embedded PbS QDs in small concentration improves the performance of the perovskite solar cells. We observed that higher concentration of PbS QDs can be embedded in FAPbI3 (FA=formamidinium) with an increase in solar cells performance and significantly longer solar cells stability.
Beyond the study of PbS QDs, we have also analyzed the preparation of perovskite QDs and the analysis of their properties, specially photoluminescence (PL) as high PL quantum yield (PLQY) is a clear indicator of low nonradiative recombination.
It is very important to highlight that the results obtained, allowed the improvement of performance of optoelectronic devices beyond PSCs as LEDs, white LED, light amplifiers, and lasers.
Finally, comment that I was strongly involved in the organization of international conferences in the field that allowed to share the results of the NO-LIMIT project with research community. The results of No-LIMIT were also disseminated in more of 20 invited contribution of the PI in this most important conferences of the field, and also in many other invited, oral and poster contributions of all the group members. The PI has been also invited to different interviews (TV, radio, press) and talks to disseminate his research to a non-academic public.
One of the aspects analyzed in No-LIMIT was the preparation of benchmark PSCs with 20% efficiency. Properties of perovskite solar cells can be also managed by the addition of innovative conjugated bulky cations as anilinium or dipropylammonium.
Facing the future commercialization of this technology we have analyzed by life cycle assessments of alternative configurations, using carbon contacts, and fabrication processes as the fast infrared annealing and comparing with other photovoltaic technologies.
The use of Pb-free system was also studied for both thin films and QDs preparing Sn-PSCs with record stability.
We have developed a new methodology for the characterization of PSCs outdoors.
The working principles of PSCs have been investigated in detail by impedance spectroscopy (IS) obtaining the equivalent circuit for PSCs.
The first objective of the No-LIMIT project is the determination and modelling of the unique properties of halide perovskite and semiconductor QDs from theoretical and experimental points of view. We consider that this objective have accomplished. We have observed that HP films with embedded PbS QDs in small concentration improves the performance of the perovskite solar cells. We observed that higher concentration of PbS QDs can be embedded in FAPbI3 (FA=formamidinium) with an increase in solar cells performance and significantly longer solar cells stability.
Beyond the study of PbS QDs, we have also analyzed the preparation of perovskite QDs and the analysis of their properties, specially photoluminescence (PL) as high PL quantum yield (PLQY) is a clear indicator of low nonradiative recombination.
It is very important to highlight that the results obtained, allowed the improvement of performance of optoelectronic devices beyond PSCs as LEDs, white LED, light amplifiers, and lasers.
Finally, comment that I was strongly involved in the organization of international conferences in the field that allowed to share the results of the NO-LIMIT project with research community. The results of No-LIMIT were also disseminated in more of 20 invited contribution of the PI in this most important conferences of the field, and also in many other invited, oral and poster contributions of all the group members. The PI has been also invited to different interviews (TV, radio, press) and talks to disseminate his research to a non-academic public.
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.
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.