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/(öffnet in neuem Fenster)) 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/(öffnet in neuem Fenster)) 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.
