Performance optimization of a solar-driven single-stage heterostructure-based thermionic generator

Abstract

<p indent="0mm">Heterostructure-based thermionic devices have high theoretical conversion efficiency and broad application prospects in the efficient utilization of solar energy. However, the irreversibility in actual heterostructure-based thermionic devices can decrease the performance of the devices. In this study, a finite time thermodynamic model of a solar-driven single-stage thermionic generator is established. The model includes a concentrated solar power, solid-state thermionic generator, and heat dissipation modules. According to the law of charge conservation and the first law of thermodynamics, the temperatures of the absorber and electrodes are calculated. The effects of output voltage, Schottky barrier, and concentration ratio on the optimal performance are studied. The results show that there are optimal output voltage and Schottky barrier to maximize the efficiency; when the concentration ratio increases, the power and efficiency increase and then decrease. Further, the optimal concentration ratios, i.e., <italic>C</italic>_{<italic>η</italic>}_,max≈1700 and <italic>C</italic>_{<italic>P</italic>}_,max≈2250, can maximize the efficiency and power reach, respectively. In this study, the results can provide some theoretical guidance for the optimal design of practical solar-driven thermionic devices.