(472g) Controlling the Effect of Slug-to-Slug Variation on the Crystal Size Distribution of Perovskite QDs: A CFD-Based Approach
AIChE Annual Meeting
2021 Annual Meeting
Continuous Crystallization Processes
Wednesday, November 10, 2021 - 2:18pm to 2:39pm
Despite the intriguing advantages of SFCs, there are still some key issues with the operation of SFCs. For example, previous studies have not accounted for the effect of slug-to-slug (S2S) variation on crystal size distribution (CSD), and the absence of a modeling and control framework for CsPbBr3 QDs made it challenging to fine-tune the QD size distribution.  In response, we have developed a computational fluid dynamics (CFD) model to elucidate the mechanism of slug formation process in a millifluidic SFC, and then combined it with a slug crystallizer model to accurately model QD size distributions and precursor concentration profiles in SFC. Specifically, the slug crystallizer model was constructed by combining a continuum model with a previously developed kinetic Monte Carlo (kMC) model.  Based on the CFD-based multiscale modeling framework (i.e., CFD + continuum + kMC model), an optimal operation problem was formulated to ensure adequate set-point (QD size) tracking, resulting in a narrow CSD. Overall, (a) the proposed multiscale model is in good agreement with the experimental results; (b) the CFD simulation highlights the region in which the SFC should be operated (i.e., stable slug flow regime); and (c) the optimizer is capable of effective simultaneous set-point tracking (QD size) and disturbance rejection (S2S variation) while ensuring a narrow CSD.
In summary, the CFD model was used to identify a stable slug regime and quantify the S2S variation in a millifluidic SFC. Additionally, a dynamic multiscale model for a SFC was developed to describe the temporal evolution of average QD size and CSD. Lastly, an optimization-driven controller scheme was implemented to ensure that the QDs match the industry specifications while maintaining a narrow CSD. Overall, the proposed work is a major leap towards continuous nano-manufacturing of metal halide perovskite QDs, which will be crucial in meeting market demands of the optoelectronics industry in the coming decade.
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