Design principle for 3D thermoelectric materials in power generators

Abstract

Thermoelectric power generation, which converts waste heat into electricity, represents a promising approach toward sustainable energy harvesting. While geometric regulation of thermoelectric materials has shown significant potential for enhancing device performance, existing theoretical and computational approaches typically rely on simplified, case-specific designs under constrained conditions. This limitation primarily stems from theoretical challenges in comprehensively understanding thermoelectric transport in three-dimensional (3D) materials under varied thermal environments. Here, we develop an analytical theoretical framework to rigorously examines power generation in 3D thermoelectric materials across diverse thermal boundary conditions. Based on this framework, we propose a universal geometric design principle to optimize 3D materials for maximum power generation and introduce a universal figure of merit that comprehensively integrates material properties, geometry, and boundary conditions. Experimental validation using optimized 3D-printed (Bi, Sb)2Te3 legs demonstrates significant enhancements in performance. This study establishes a robust theoretical foundation and practical design strategy, advancing thermoelectric energy harvesting beyond traditional material-property-based optimizations.