Highly efficient photovoltaic energy conversion using surface acoustic waves in piezoelectric semiconductors
We present a theoretical proposal for a novel principle for photovoltaic energy conversion using surface acoustic waves (SAWs). A SAW produces periodic modulation of the electric potential in a piezoelectric semiconductor. The photoexcited electron and holes are separated to the maxima and minima of the SAW potential in a large volume occupied by the SAW. The moving SAW transports the electric charges in the ambipolar manner with the speed of sound to the collecting electrodes. The electrodes are made from two different materials that collect electrons and holes separately and generate the output dc current. Most steps of the proposed process have been already demonstrated experimentally in the literature. However, the application of SAW for photovoltaic energy generation has not been demonstrated. We present arguments why the active design using SAW should have much higher efficiency than the passive design of the existing photovoltaic devices and how to mitigate the energy necessary to generate and maintain SAW in the system.
We propose to make multiple electrodes of the p and n type parallel to the direction of SAW propagation, as shown in the figure. These electrodes create transverse staggered electric field and can quickly collect electrons and holes, like unloading passengers off a train to multiple platforms.