WPTherml: A Python Package for the Design of Materials for Harnessing Heat

Abstract

WPTherml is a Python package for the design of materials with tailored optical and thermal properties for the vast number of energy applications where control of absorption and emission of radiation, or conversion of heat to radiation or vice versa, is paramount. The optical properties are treated within classical electrodynamics via the Transfer Matrix Method which rigorously solves Maxwell's equations for layered isotropic media. A flexible multilayer class connects rigorous electrodynamics properties to figures of merit for a variety of thermal applications, and facilitates extensions to other applications for greater reuse potential. WPTherml can be accessed at https://github.com/FoleyLab/wptherml.

Accelerating the discovery of multilayer nanostructures with analytic differentiation of the transfer matrix equations

“…We have implemented the analytic gradient formalism in a development version of WPTherml [28], which has permitted careful testing of its efficiency as compared to a numerical gradient formalism based on centered finite differences. We have also applied our analytic gradient formalism to the geometry optimization of multilayer structures for (a) selective thermal emission and filtration for incandescent lighting, (b) enhanced solar absorption of silicon-based PV films, and (c) enhanced optical absorption of organic dyes embedded in thin films.…”

“…This methodology is based upon a simple theoretical formulation of analytical gradients of the transfer-matrix equations with respect to geometric parameters of the multilayers. A practical implementation of this methodology is provided in open-source software package WPTherml [28], and we have leveraged this implementation to demonstrate the usefulness of this methodology to designing high efficiency incandescent structures, high-performance antireflection coatings for PV cells, and optical cavities for enhanced light harvesting by aggregates of organic chromophores in thin film. The methodology presented here will provide an important tool for the design and optimization of multilayer nanomaterials for a myriad of applications where tailored optical and thermal radiation properties are paramount.…”

“…In the results presented in our main text, we use dispersive models for both materials that are described in Ref. [28]; the dispersive nature of AlN in particular is challenging for the FDTD method and obscures comparison. The close agreement between the emissivities and derivatives of the emissivities as computed by WPTherml and those computed by full-wave simulation support the claim that our method provides predictive power for the optimization and design of structures whose performance derives from optical quantities like the emissivity.…”

“…As seemingly simple as such structures are, the spectral shaping capabilities they offer have enabled passive cooling well below ambient temperature [19][20][21][22][23], and incandescent lighting with efficiencies meeting or exceeding LED bulbs [27]. Also important is that the optical and thermal emission properties of such structures can be efficiently simulated; for example, several of the authors have developed an open-source package called WPTherml [28] that is based on an efficient analytic method for solving Maxwell's equations for such structures known as the transfer-matrix method (TMM) [29].…”

Twenty years of exceptional success: The molecular education and research consortium in undergraduate computational chemistry (MERCURY)

“…Key scientific outcomes so far include the discovery of an emergent optical phenomenon in composite nanoparticles known as “scattering‐mediated absorption”, [ 456–458 ] and the development of an open‐source software package, WPTherml, for designing materials for harnessing heat. [ 459,460 ]…”