# Superlattice design for optimal thermoelectric generator performance

## TL;DR

This paper designs an optimal superlattice thermoelectric generator using the energy bandpass filter approach, identifying structures that maximize efficiency and power output through advanced modeling and analysis.

## Contribution

It introduces a superlattice design with Gaussian barrier thickness distribution that achieves near-ideal efficiency and power, validated by non-equilibrium Green's function simulations.

## Key findings

- Maximum power output of 0.32-0.46 MW/m^2
- Efficiency between 43% and 54% of Carnot
- High electronic figure of merit zT_el=6

## Abstract

We consider the design of an optimal superlattice thermoelectric generator via the energy bandpass filter approach. Various configurations of superlattice structures are explored to obtain a bandpass transmission spectrum that approaches the ideal ``boxcar'' form, which is now well known to manifest the largest efficiency at a given output power. Using the non-equilibrium Green's function formalism coupled self-consistently with the Poisson's equation, we identify such an ideal structure and also demonstrate that it is almost immune to the deleterious effect of self-consistent charging and device variability. Analyzing various superlattice designs, we conclude that superlattices with a Gaussian distribution of the barrier thickness offers the best thermoelectric efficiency at maximum power. It is observed that the best operating regime of this device design provides a maximum power in the range of 0.32-0.46 $MW/m^2$ at efficiencies between 54\%-43\% of Carnot efficiency. We also analyze our device designs with the conventional figure of merit approach to counter support the results so obtained. We note a high $zT_{el}=6$ value in the case of Gaussian distribution of the barrier thickness. With the existing advanced thin-film growth technology, the suggested superlattice structures can be achieved, and such optimized thermoelectric performances can be realized.