Spectral graph theory for characterization and homogenization of grain boundary networks

Johnson, Oliver K.; Lund, Jarrod M.; Critchfield, Tyler

doi:10.1016/j.actamat.2017.11.054

Cited by 16 publications

(5 citation statements)

References 59 publications

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“…A graph-based representation allows us to leverage well studied algorithms from graph theory along with their optimized implementations. We note that graphs have been used in many material science models ranging from molecular structure 15,16 to grain boundaries 17,18 and porous microstructure. 19 Discretized microstructure is represented as a labeled, weighted, undirected graph G = (V,E,W,L) ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Microstructure design using graphs

Zebrowski

Żola

et al. 2018

npj Comput Mater

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Thin films with tailored microstructures are an emerging class of materials with applications such as battery electrodes, organic electronics, and biosensors. Such thin film devices typically exhibit a multi-phase microstructure that is confined, and show large anisotropy. Current approaches to microstructure design focus on optimizing bulk properties, by tuning features that are statistically averaged over a representative volume. Here, we report a tool for morphogenesis posed as a graph-based optimization problem that evolves microstructures recognizing confinement and anisotropy constraints. We illustrate the approach by designing optimized morphologies for photovoltaic applications, and evolve an initial morphology into an optimized morphology exhibiting substantially improved short circuit current (68% improvement over a conventional bulk-heterojunction morphology). We show optimized morphologies across a range of thicknesses exhibiting self-similar behavior. Results suggest that thicker films (250 nm) can be used to harvest more incident energy. Our graph based morphogenesis is broadly applicable to microstructure-sensitive design of batteries, biosensors and related applications.

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Section: Resultsmentioning

confidence: 99%

Microstructure design using graphs

Zebrowski

Żola

et al. 2018

npj Comput Mater

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“…For the (connected) graphs considered here, L is singular with a nullity of one. We note that graphical representations of materials microstructures have been employed by Johnson et al to characterize grain-boundary networks 33 and for microstructural design 34 .…”

Section: Resultsmentioning

confidence: 99%

Evolving information complexity of coarsening materials microstructures

Rickman,

Barmak,

Chen

et al. 2023

Sci Rep

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The temporal evolution of microstructural features in metals and ceramics has been the subject of intense investigation over many years because deviations from normal grain growth behavior are ubiquitous and strongly dictate observed mechanical and magnetic properties. To distinguish among different grain growth scenarios, we examine the time evolution of the information content of both synthetic and experimental coarsening microstructures as quantified by both a computable information density (CID) and a spectral entropy along with selected metrics and measures of shared information and interaction strength. In these approaches, microstructural evolution is described in terms of two time series representations, namely: (1) strings and their compressed counterparts that reflect the information contained in the configuration of a system over time, and (2) the spectra of graph Laplacians that embody the information contained in a coarsening grain network. These approaches permit one to characterize dynamically evolving microstructures and to identify correlation times associated with different coarsening scenarios. Moreover, as the information content of a system is a proxy for the entropy, a thermodynamic description of grain growth is also described.

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“…Fractal analysis was utilized to confirm the validity of the designed morphologies through similarity comparison of naturally occurring fractals. Fractal analysis methods such as fractal dimension [8], lacunarity [17], and succolarity [18], can be used to infer the specialized functions of a structure such as the movement of electricity through the fractal dendrites in neurons and the transport of particles in the bronchi of the lungs [19]. In this case, fractal analysis was used to confirm the validity of the solar cell microstructure in transporting and generating excitons.…”

Section: Fractal Analysismentioning

confidence: 99%

Computational design of organic solar cell active layer through genetic algorithm

Ardayfio¹

2019

Preprint

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The active layer microstructure of organic solar cells is critical to efficiency. By studying the photovoltaic properties of organic solar cell's microstructure, it is possible to increase the efficiency of the solar cell. A graph-based microstructure model was employed to approximate the efficiency, measured as short circuit current, of a solar cell given a microstructure. Through probabilistic graph-based optimization, a class of microstructures were found with an efficiency surpassing that of more conventional morphologies. These optimized solar cells surpass the efficiency of more conventional photovoltaic devices as they better facilitate charge transport, generation, and dissociation. A device was designed with a 40.29% increase in short circuit current from the solar cells with the currently believed optimal morphology. The designed morphologies feature two dendritic clusters of the donor material poly(3-hexylthiophene-2,5-diyl) (P3HT) and the acceptor material phenyl-C61-Butyric-Acid-Methyl Ester (PCBM). The designed microstructure's increase in performance contrasts with more conventional structures featuring interdigitated or bilayer strands of P3HT and PCBM. The change of microstructure morphology through graph-based evolution obtains an organic solar cell with an efficiency significantly greater than conventional organic solar cells, proves the validity of graph-based microstructure models for simulation in materials science, and advances the vision of an inexpensive, efficient form of renewable energy.

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Spectral graph theory for characterization and homogenization of grain boundary networks

Cited by 16 publications

References 59 publications

Microstructure design using graphs

Microstructure design using graphs

Evolving information complexity of coarsening materials microstructures

Computational design of organic solar cell active layer through genetic algorithm

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