Title : Screening of solvents for perovskite solar cells using reverse engineering approach
Abstract:
Perovskite solar cells (PSC) are a promising technology in the field of photovoltaics due to their high performance and simple fabrication methodology. Important achievements in device stability and power conversion efficiency have been obtained by inorganic-organic perovskites through the fine tuning of cation size and stoichiometry proportions. However, the dependency on highly toxic solvents that affects both human health and the environment needed to solubilize perovskite precursors still limits the upscaling of PSCs to larger solar modules. The search of alternative solvents relies primarily on trial-and-error approaches due to the lack of knowledge of both the precursor solubility mechanisms and the perovskite crystallization during film formation. In this work we propose a reverse engineering methodology based on COSMO-RS to find solvent substitutes for the triple cation lead Cs0.05FA0.85MA0.10PbI2.90Br0.10. Due to the complexity of the system in solution because of the formation of complexes between precursors and the solvents, predictive thermodynamic methods cannot be applied to calculate the solubility values. Therefore, the search has to be performed by comparing several molecular descriptors related to the solubility power of the solvent. The σ-potential obtained with COSMO-RS serves as a descriptor of the medium’s response to a molecule. To compare the σ-potential curves for many molecules, Functional Principal Component Analysis (FPCA) is applied, reducing a curve to two dimensions. FPCA allows to compare our set of ~5000 molecules through their distance to the target solvent. Our screening using this methodology led to molecules which have been all reported in the literature, as well as new molecules never used for our system. Experimental results of solubility measurements are explained using other molecular descriptors, enabling a deeper understanding of the interactions between solvents and perovskite precursors during the solubility phase of PSC production.
Audience Take Away
- Discover the practical problems surrounding the transition to the new solar cell materials.
- Learn about the Reverse Engineering methodology and COSMO-RS through a research application.
- New approach for the search of general solvents capable of solubilizing perovskite precursor solar cells.
