In Fullerene_PSC project, we have used computational resources provided by EuroHPC and Red Española de Supercomputación for understanding the fullerene-perovskite interactions and improve the design of fullerene derivatives for enhanced performance in PSCs.
• We began by performing detailed periodic boundary condition calculations using VASP to model the adsorption of various fullerenes. These calculations were designed to uncover the adsorption modes and binding energies of these fullerenes on pristine and defective perovskite surfaces.
• We extended our analysis to surfaces with common defects, such as Cs/MA vacancies (surface charge of -1), Pb vacancies (-2), and I antisites (-3). These studies revealed significant variations in the adsorption behavior and electronic properties of the fullerenes depending on the type and presence of these defects. We discovered that fullerenes preferentially orient themselves to maximize contact with the surface, particularly on defective perovskites surfaces.
• Recognizing the limitations of molecular models, we shifted back to periodic boundary condition calculations with charged surfaces. This approach provided a more accurate representation of the charge transfer dynamics.
• Considering all the data generated for several fullerenes in Cs and MA lead perovskite surfaces, we began analyzing the data to identify key descriptors that correlate computational findings with experimental parameters.
Main Results Achieved:
o We identified that the adsorption of fullerenes on perovskite surfaces presents attractive binding energies where the lowest energy adsorption sites imply to maximize the number of fullerene-perovskite contacts.
o I antisite defects induces significant surface reconstruction. The presence of I-I-I moieties implies surface reconstruction with the subsequent formation of trap states, which may affect the solar cell performance.
o The adsorption of fullerenes eliminates trap states by promoting the surface reconstruction. The reconstructed surfaces do not show trap states anymore. This new reconstructed surfaces are higher in energy compared to the lowest energy surface configuration with trap states which means that only appear stable when fullerenes are adsorbed, unveiling a critical mechanism for passivating trap states.
Exploitation and Dissemination of Results:
• Scientific Publications and Conferences: The project’s findings have been disseminated through a series of scientific publications and presentations at international conferences. For the moment, one publication can be consulted (10.1002/chem.202401283) and many more are in preparation. Our work has been disseminated in catalan, Spanish, and international conferences like ACS fall 2023 and 244th ECS. Moreover, I was invited to EuroHPC conference in 2023 to disseminate the work carried out.
• Open Access Data: All computational data, including energies and structural models, have been made available through open access repositories (NOMAD) or supplementary materials in our publications.
• Future Directions: Given the promising results and the wealth of data generated, the project will continue to explore new fullerene derivatives and further refine the understanding of their interactions with perovskites.
