Temperature-Dependent Analysis of Solid-State Photon-Enhanced Thermionic Emission Solar Energy Converter

Yang Yang,Jun Qin,Peng Xu,Yong Bai,Wei Cao,Bing Zhu,Bo Wang,Xiao Bai

doi:10.3390/en13071554

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 ( J 0 ) and open-circuit voltage ( V o c ) 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 J 0 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 ( − d V o c / d T ) 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 diffusion 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.

Highlights

For concentrator photovoltaic systems and solar arrays of near-solar space probes, solar cells are generally exposed to high temperatures [1,2]
GaAs with a doping density of 1 × 1019 cm−3 was used as the absorber, and AlGaAs was used as the barrier layer in the solid-state photon-enhanced thermionic emission (PETE) converter [17]
An analytical model based on one-dimensional steady-state continuity is presented to converters are suitable for working conditions under equation high temperatures and investigate the temperature-dependent performance of the solid-state high light intensity

Summary

Introduction

For concentrator photovoltaic systems and solar arrays of near-solar space probes, solar cells are generally exposed to high temperatures [1,2]. The performance of solar cells degrades with the increase in temperature [3]. Efficiency degradation is primarily due to the decrease in open-circuit voltage (Voc ) with the increase in temperature [1,2,3,4,5]. The reverse saturation current density (J0 ) is a critical parameter because it exponentially increases with increasing temperature and decreases. J0 is a material-dependent parameter that relies on the bandgap and doping level of the material [4,5]. Wide bandgap solar cells, including photovoltaic cells made from GaInP [6], Energies 2020, 13, 1554; doi:10.3390/en13071554 www.mdpi.com/journal/energies

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