# Superlattice nanowire heat engines with direction-dependent power output and heat current

## TL;DR

This paper introduces a superlattice nanowire heat engine with staircase-like quantum dot energy levels, enabling direction-dependent power output and heat current, and functioning as a heat diode with negative differential thermal conductance.

## Contribution

It proposes a novel superlattice nanowire heat engine design with staircase energy levels, enhancing power and efficiency over uniform-level designs and enabling diode-like heat control.

## Key findings

- Enhanced power output and efficiency compared to uniform energy level nanowires.
- Direction-dependent heat current and power output.
- Demonstration of heat diode functionality with negative differential thermal conductance.

## Abstract

Heat engines (HEs) made of low dimensional structures offer promising applications in energy harvesting due to their reduced phonon thermal conductance. Many efforts have been devoted to the design of HEs made of quantum-dot (QD) superlattice nanowire (SLNW), but only SLNWs with uniform energy levels in QDs were considered. Here we propose a HE made of SLNW with staircase-like QD energy levels. It is demonstrated that the nonlinear Seebeck effect can lead to significant electron transports for such a nanowire with staircase-like energy levels. The asymmetrical alignment of energy levels of quantum dots embedded in nanowires can be controlled to allow resonant electron transport under forward temperature bias, while they are in off-resonant regime under backward bias. Under such a mechanism,the power output and efficiency of such a SLNW are better than SLNWs with uniform QD energy levels. The SLNW HE has direction-dependent power output and heat current. In addition, the HE has the functionality of a heat diode with impressive negative differential thermal conductance under open circuit condition.