Designing Anisotropic Microstructures with Spectral Density Function

TL;DR

This paper introduces a spectral density function-based method for designing and reconstructing anisotropic microstructures in 2D and 3D, enabling efficient optimization of material performance in applications like organic photovoltaic cells.

Contribution

It presents a novel spectral density function approach for rapid, low-dimensional reconstruction and quantification of anisotropic microstructures, advancing material design capabilities.

Findings

Anisotropic microstructures outperform isotropic designs in photovoltaic applications.

The spectral density function effectively quantifies anisotropy with a scalar index.

The method enables efficient microstructure optimization and characterization.

Abstract

Materials' microstructure strongly influences its performance and is thus a critical aspect in design of functional materials. Previous efforts on microstructure mediated design mostly assume isotropy, which is not ideal when material performance is dependent on an underlying transport phenomenon. In this article, we propose an anisotropic microstructure design strategy that leverages Spectral Density Function (SDF) for rapid reconstruction of high resolution, two phase, isotropic or anisotropic microstructures in 2D and 3D. We demonstrate that SDF microstructure representation provides an intuitive method for quantifying anisotropy through a dimensionless scalar variable termed anisotropy index. The computational efficiency and low dimensional microstructure representation enabled by our method is demonstrated through an active layer design case study for Bulk Heterojunction Organic Photovoltaic Cells (OPVCs). Results indicate that optimized design, exhibiting strong anisotropy, outperforms isotropic active layer designs. Further, we show that Cross-sectional Scanning Tunneling Microscopy and Spectroscopy (XSTM/S) is as an effective tool for characterization of anisotropic microstructures.