Temperature-dependent analysis of solid-state photon-enhanced thermionic emission solar energy converter

Abstract

Solid-state photon-enhanced thermionic emission (PETE) solar energy converters are newly proposed devices that can directly convert solar energy into electrical power at high temperatures. An analytical model based on a one-dimensional steady-state equation is developed to analyze the temperature-dependent performance of the solid-state PETE converter. The treatment used to derive the reverse saturation current density (J0) and open-circuit voltage (Voc) of the solid-state PETE converter is similar to that used in photovoltaic cells. Thus, their performances at elevated temperatures can be compared. Analysis results show that J0 of the solid-state PETE converter with a GaAs absorption layer is approximately three orders of magnitude lower, and the decrease rate of open-circuit voltage (-dVoc/dT) is smaller than that of a practical GaAs photovoltaic cell. The improved performance of the solid-state PETE converter at high temperatures is attributed to the simultaneous use of diffiusion and ballistic transport to harvest photo-generated electrons. The results presented in this paper demonstrate that, besides using wide bandgap materials and increasing doping density, harvesting solar energy via PETE effect can effectively improve the performance of solar cells at elevated temperatures.