Periodic Reporting for period 1 - SMARTCELL (Sustainable Materials for development of Advanced Renewable Technologies for the next generation solar CELLs)
Periodo di rendicontazione: 2021-08-01 al 2024-07-31
Renewable forms of energy are of key importance towards net zero CO2 emissions, which will restrict the consumption of fossil fuels and limit the extent of anthropogenic climate change. This statement is even further reinforced by the fact that 5 out of 17 Sustainable Development Goals defined by the United Nation are directly related to clean, renewable, and sustainable energy resources. As such, solar energy has the potential to play a central role in the global energy system due to the scale of solar resources, its predictability, and its ubiquitous nature. However, in order to meet the global energy demand, photovoltaic (PV) technologies need to go beyond the mainstream (crystalline-Si (c-Si), thin film CdTe and Cu(In,Ga)Se2 (CIGS)) which currently dominate the PV market. These cannot keep pace with the ever more creative and ambitious future of thin, flexible, transparent solar technologies for everything from zero-energy buildings to smart sensors for the Internet-of-Things to e-textiles for device charging on-the-go. The market needs an innovative alternative, one that is not only commercially competitive, but also in line with emerging social values of sustainability, circularity, and responsibility.
SMARTCELL proposes an innovative PV technology based on earth-abundant, low-cost, direct bandgap semiconductors for development of novel ultra-thin solar cells. SMARTCELL will implement novel technological solutions based on advanced nanofabrication methods for synthesis of high crystal quality zinc phosphide (Zn3P2) ) absorbers, which together with design and optimization of the device interfaces and the cell architecture will lead to achievement of unprecedented device efficiencies, especially among the earth-abundant emerging PV technologies. These efficiencies will give SMARTCELL the opportunity to demonstrate scalable, cost-effective, and environmentally-friendly ultrathin-film PV technology. The working principle of SMARTCELL is based on a holistic interplay between materials simulations, combinatorial and factorial synthesis studies, and atomic-resolution structural and electronic characterization techniques, which will allow predictive structure-property-function relationships, and cutting-edge engineering of absorber properties.
SMARTCELL proposes an innovative PV technology based on earth-abundant, low-cost, direct bandgap semiconductors for development of novel ultra-thin solar cells. SMARTCELL will implement novel technological solutions based on advanced nanofabrication methods for synthesis of high crystal quality zinc phosphide (Zn3P2) ) absorbers, which together with design and optimization of the device interfaces and the cell architecture will lead to achievement of unprecedented device efficiencies, especially among the earth-abundant emerging PV technologies. These efficiencies will give SMARTCELL the opportunity to demonstrate scalable, cost-effective, and environmentally-friendly ultrathin-film PV technology. The working principle of SMARTCELL is based on a holistic interplay between materials simulations, combinatorial and factorial synthesis studies, and atomic-resolution structural and electronic characterization techniques, which will allow predictive structure-property-function relationships, and cutting-edge engineering of absorber properties.
During the 15 month duration of the project, SMARTCELL has achieved the following objectives:
i) Investigation and engineering of the fundamental properties of Zn3P2. This includes critical insights into structural and vibrational properties, such as providing the reference Raman spectrum of Zn3P2, with a complete analysis of all Raman active modes from both experimental and theoretical perspectives [https://doi.org/10.1039/D1CP04322F]. Optoelectronic behavior of Zn3P2 was investigated using temperature and power-dependent photoluminescence studies [https://doi.org/10.1039/D1MA00922B] while complete electronic band structure was determined by performing high energy and spatial resolution electron energy-loss spectroscopy in aloof and inner beam geometry in a scanning transmission electron microscope [https://doi.org/10.1002/adfm.202105426].
ii) Compositional defects, such as phosphorus interstitials and zinc vacancies were identified as the main doping mechanism responsible for p-type conductivity of Zn3P2 [https://doi.org/10.1039/D2FD00055E]. This was determined through compositional stoichiometry variation of Zn3-xP2+x monocrystalline thin films. We used experimental methods, such as electron and X-ray diffraction and Raman spectroscopy, along with density functional theory calculations. Furthermore, we unveiled the impact of doping caused due changes in the Zn/P ratio on the electrical properties of the material [https://doi.org/10.1016/j.solmat.2023.112194]. The ability of zinc phosphide to form off-stoichiometric compounds provides a new promising opportunity for tunable functionality that benefits applications.
iii) Solar cell demonstration with 4.4 % efficiency. We demonstrate a minimally processed Zn3P2-based solar cell, by employing an ITO top contact on a polycrystalline Zn3P2 thin film [https://dx.doi.org/10.2139/ssrn.4367176]. We analyze the illumination-dependent electronic behavior, as well as the external quantum efficiency to determine the dominant limiting factors of the device. Additionally, we propose a working principle for the device, highlight the role of ITO, and investigate the contribution of Zn3P2 to the overall working of the device.
SMARTCELL has directly contributed to >10 publications, with Mirjana Dimitrievska being the first/last author on 7 publications. The results of SMARTCELL have been disseminated at 10 international material-science-oriented conferences, which included 6 invited and 4 contributed talks. Furthermore, SMARTCELL was one of the main organizers of the SeeFuturePV symposium (Latsis Symposium on Earth-Abundant Materials for Future Photovoltaics https://www.epfl.ch/labs/lmsc/seefuturepv/(si apre in una nuova finestra)) which took place at EPFL, Lausanne, Switzerland in June 2022.
SMARTCELL has made significant contributions to rising awareness of PV technology to the general public. This was achieved through the series of invited talks at public events, such as USERN congress and Zonta International meetings. Additionally, SMARTCELL has been involved in promoting science to children through organization of workshop Dancing with Molecules within the Science is Wonderful festival (https://scienceiswonderful.eu/(si apre in una nuova finestra)) as well local participation at school events.
Finally, in 2022, Mirjana Dimitrievska, has received two awards for her contributions to development of sustainable materials for energy applications (USERN award 2022 and Prix Zonta 2021), along with the distinctions as the Emerging Young Leader in the Energy Field (IOP Science). These contributions included the results achieved during the duration of the SMARTCELL project. In this regard, SMARTCELL was terminated early (after 15 months of duration, instead of 36) due to Mirjana Dimitrievska obtaining a tenure track group leader position at the Swiss Federal Laboratories for Materials Science and Technology (EMPA), Zurich, Switzerland.
i) Investigation and engineering of the fundamental properties of Zn3P2. This includes critical insights into structural and vibrational properties, such as providing the reference Raman spectrum of Zn3P2, with a complete analysis of all Raman active modes from both experimental and theoretical perspectives [https://doi.org/10.1039/D1CP04322F]. Optoelectronic behavior of Zn3P2 was investigated using temperature and power-dependent photoluminescence studies [https://doi.org/10.1039/D1MA00922B] while complete electronic band structure was determined by performing high energy and spatial resolution electron energy-loss spectroscopy in aloof and inner beam geometry in a scanning transmission electron microscope [https://doi.org/10.1002/adfm.202105426].
ii) Compositional defects, such as phosphorus interstitials and zinc vacancies were identified as the main doping mechanism responsible for p-type conductivity of Zn3P2 [https://doi.org/10.1039/D2FD00055E]. This was determined through compositional stoichiometry variation of Zn3-xP2+x monocrystalline thin films. We used experimental methods, such as electron and X-ray diffraction and Raman spectroscopy, along with density functional theory calculations. Furthermore, we unveiled the impact of doping caused due changes in the Zn/P ratio on the electrical properties of the material [https://doi.org/10.1016/j.solmat.2023.112194]. The ability of zinc phosphide to form off-stoichiometric compounds provides a new promising opportunity for tunable functionality that benefits applications.
iii) Solar cell demonstration with 4.4 % efficiency. We demonstrate a minimally processed Zn3P2-based solar cell, by employing an ITO top contact on a polycrystalline Zn3P2 thin film [https://dx.doi.org/10.2139/ssrn.4367176]. We analyze the illumination-dependent electronic behavior, as well as the external quantum efficiency to determine the dominant limiting factors of the device. Additionally, we propose a working principle for the device, highlight the role of ITO, and investigate the contribution of Zn3P2 to the overall working of the device.
SMARTCELL has directly contributed to >10 publications, with Mirjana Dimitrievska being the first/last author on 7 publications. The results of SMARTCELL have been disseminated at 10 international material-science-oriented conferences, which included 6 invited and 4 contributed talks. Furthermore, SMARTCELL was one of the main organizers of the SeeFuturePV symposium (Latsis Symposium on Earth-Abundant Materials for Future Photovoltaics https://www.epfl.ch/labs/lmsc/seefuturepv/(si apre in una nuova finestra)) which took place at EPFL, Lausanne, Switzerland in June 2022.
SMARTCELL has made significant contributions to rising awareness of PV technology to the general public. This was achieved through the series of invited talks at public events, such as USERN congress and Zonta International meetings. Additionally, SMARTCELL has been involved in promoting science to children through organization of workshop Dancing with Molecules within the Science is Wonderful festival (https://scienceiswonderful.eu/(si apre in una nuova finestra)) as well local participation at school events.
Finally, in 2022, Mirjana Dimitrievska, has received two awards for her contributions to development of sustainable materials for energy applications (USERN award 2022 and Prix Zonta 2021), along with the distinctions as the Emerging Young Leader in the Energy Field (IOP Science). These contributions included the results achieved during the duration of the SMARTCELL project. In this regard, SMARTCELL was terminated early (after 15 months of duration, instead of 36) due to Mirjana Dimitrievska obtaining a tenure track group leader position at the Swiss Federal Laboratories for Materials Science and Technology (EMPA), Zurich, Switzerland.
SMARTCELL has a strong innovative nature by developing new materials (sustainable semiconductors with tailored properties), technological processes (synthesis processes to bypass the material/substrate mismatch) and characterization tools (development of fast and non-destructive techniques for defect identification) with high scientific and commercial potential. Another major innovation of SMARTCELL is its scientific approach which spans a full cycle of materials development, starting from basic research up to device demonstration. SMARTCELL can have a transformative impact in a market with enormous potential social and economic value. Silicon may remain the go-to material for rigid modules, but the proposed ultrathin solar cell devices will find new barely-tapped markets, such as flexible solar cell for applications in wearables, smart buildings, Internet of Things, even smart robotics. Such applications will bring solar solutions within reach of all citizens and businesses, and will lead to lower renewable energy costs and jobs creation from the “doing” to the “thinking” ends of the economy. SMARTCELL contributes to this scenario through convincing demonstration of efficient, scalable and recyclable materials and architectures, paving the way for a future where this is the new standard.