High-Throughput Screening from Binary Combinatorial Library of Zero-Dimensional Lead-Free Halide Perovskites for Photocatalysis

The urgent demand for lead-free, stable, and efficient catalysts for energy conversion applications necessitates efficient and fast discovery of materials.1 In this study, we present a one-dimensional (1D) binary combinatorial library of zero-dimensional lead-free halide perovskites, specifically MA3Bi2I9 and Cs3Bi2I9, using an automated pipetting robotic method. Leveraging Bayesian optimization for high-throughput screening, we extensively investigated the properties of these perovskites. Both end members maintain a hexagonal crystal structure with P63/mmc symmetry. However, the combinatorial library exhibits significant variations in lattice parameters and crystal distortions, despite retaining the hexagonal structure.<br/>High-throughput screening was conducted to assess the ambient and water stability of the binary library by analysing their band gaps via absorbance spectra. The photocatalytic performance against rhodamine B dye revealed that the composition with 49% Cs substitution possesses the highest rate constant, achieving complete degradation of the dye within 15 minutes. This optimal composition shows the most significant change in surface potential under white light illumination and contains iodine vacancies, as identified by X-ray photoelectron spectroscopy. Additionally, cathodoluminescence and photoluminescence spectra indicate the presence of shallow defect states, which contribute to the mitigation of charge carrier recombination. Our hunt for identifying an efficient catalyst within a 1D binary combinatorial library has arrived at a significant finding, demonstrated by the successful degradation of toxic dye.<br/>Our findings highlight the potential of these lead-free halide perovskites as efficient catalysts for energy conversion applications. The demonstrated stability, photocatalytic efficiency, and defect management in the 49% Cs-substituted composition present a promising pathway for future research and development in water splitting, and CO2 conversion.<br/>(1) Dubey, A.; Sanchez, S. L.; Yang, J.; Ahmadi, M. Lead-Free Halide Perovskites for Photocatalysis via High- Throughput Exploration. Chem. Mater. 2024, 36, 2165–2176. https://doi.org/10.1021/acs.chemmater.3c03186.