Demonstration of a hot-carrier photovoltaic cell

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 (c) 2013 John Wiley & Sons, Ltd.