High-performance Photon-enhanced thermionic emission solar energy converters with AlxGa1−xAs∕GaAs cathode under multilevel built-in electric field

A transmission mode AlxGa1−xAs∕GaAs photocathode consisting of a composition-graded window layer and an exponential-doping emission layer is proposed to improve the performance of photon-enhanced thermionic emission (PETE) solar energy converters. The theoretical model with this complex photocathode is deduced based on one-dimensional continuity equations to analyze the characteristics of the device. It is found the multilevel built-in electric fields can effectively enhance the conversion efficiency and response of the entire spectrum in contrast to other photocathode structures. Because of less heterojunction interface recombination losses and greater transport capacity of photoelectrons toward emissive surface. Moreover, the effect of Al proportion variation in the window layer and the thickness of the window layer and emission layer on performance is discussed. The model would provide theoretical guidance for better performance of PETE device.