Lifting Off Spatial Degeneracy of Functions, Where Does It Lead Us for Photovoltaic Device Systems?

Abstract

The defact standard of a solar cell is that electric power generation is made at the same place as photoharvesting is performed, i.e., the function of photoharvesting/photoreception is spatially degenerated with that of electric power generation (photo-electroconversion). Here, in this review paper, we investigate how liberated we are when the degeneracy is lifted off. A conventional concentrator system is, in a sense, a system in which the primary photoharvesting place is decoupled from the photo-conversion part, but is too bulky because the two parts are connected three-dimensionally by photons. We propose a two-dimensional photoreceptor-conversion (2DPRC) scheme in which the photoreception part is spatially decoupled from, but is two-dimensionally connected to the photo-conversion part by a redirection waveguide (RWG). The whole system is in an edge-illumination/photoinjection configuration and concentrator system is quite naturally built, and the edge-injection lift off the trade-off between photo-absorption and photo-carrier collection in the conventional solar cell, leading to a possible high conversion efficiency.