Raising the efficiency bar for thermoelectric technology

With its high-power density, compactness, consistency and service life, thermoelectric (TE) technology — which converts heat into electricity — has emerged as a promising solid-state energy solution in recent years. But thermal-electric conversion efficiency still lags behind that of traditional heat engines, prompting much research into the role of interfacial electrical resistance in thermoelectric generator systems (TEGS).

Studies have yet to reveal much about the role of thermal resistance (resistance to interfacial thermal flow between two surfaces), however, and there remains a conspicuous gap between theoretical predictions and practical performance.

Motivated by this discrepancy, Qian et al. demonstrated that, beyond interfacial electrical resistance, the thermal resistance arising from incomplete contact between the heat source/sink and the TEGS plays a critical role in limiting device performance. They also devised a structural design methodology that minimizes the negative effects of thermal resistance.

“We show that optimizing structural parameters — such as leg height and cross-sectional area — can effectively offset the adverse impact of interfacial resistance,” said author Kun Song.

The researchers developed a cross-dimensional model to capture a TEG’s fully coupled thermal–electric behavior. Results revealed that interfacial cracks substantially degrade performance by increasing thermal resistance at the device–source/sink junctions, whereas the influence of ceramic substrates remains minimal when their thickness is less than 1 millimeter.

“Our objective is to narrow the gap between theoretical and practical performance by refining the theoretical framework and ultimately enhancing the application prospects of TE technology,” said Song. “With ongoing breakthroughs in materials and system-level integration, thermoelectric generators are poised for transformative growth, enabling efficient waste-heat recovery and self-powered technologies across industrial, aerospace, and next-generation electronic applications.”

Source: “Effect of interfacial thermal resistance on the performance of thermoelectric generator systems,” by Shankang Qian, Yiwei Duan, Zelong Dong, Guosong Liu, Baitong Lu, Haibing Yang, Shichao Xing, Shuang Wang, and Kun Song, Journal of Renewable and Sustainable Energy (2026). The article can be accessed at: https://doi.org/10.1063/5.0305556 .