Demonstration of a hot-carrier photovoltaic cell

Abstract

We demonstrate a new hot-carrier photovoltaic cell based on the resonant tunnelling of hot electrons from a narrow-band-gap semiconductor to a wider-band-gap semiconductor. Hot electrons are photogenerated at a variety of wavelengths in a GaAs absorber followed by resonant tunnelling through a double-barrier quantum well into an AlGaAs collector, forming an energy-selective interface in the centre of the device. We show theoretically the presence of a tunnel current from the absorber to the collector under illumination, offering a method to extract carriers from a hot-electron distribution at zero bias. We experimentally demonstrate a hot-carrier photovoltaic cell based on this concept. Two features of its measured current–voltage characteristic, namely the peak to valley current ratio and the current peak voltage, are shown to vary with the wavelength of illumination in a way that clearly demonstrates hot-carrier extraction. Copyright © 2013 John Wiley & Sons, Ltd.