Scalable Nanophotonic Light Management Design for Solar Cells

Abstract

The current trend in wide adoption of solar energy is encouraging in the context of current projections of increasing energy consumption and the dire need to decrease carbon emissions. The solar industry has expanded due to scientific advances in the power conversion efficiency of solar modules. In order maintain a rapid pace of adoption and further decrease electricity costs, converting each photon becomes increasingly important. This work focuses on nanophotonic approaches to increasing the power conversion efficiency of different solar photovoltaic designs. The projects voluntarily impose certain design constraints in order to be compatible with the large scale manufacturing needed by the solar industry. A focus was given to designs that can leverage the promising technology of nanoimprint lithography. Amorphous silicon tandem cells with embedded nanophotonic patterning attempted to increase absorption while minimizing materials and time costs. Simulated designs of Copper Indium Gallium Diselenide absorbers showed that the management of excited carriers is equally as important as light management in decreasingly thin absorber layers. Near perfect anti-reflection structures were given a detailed physical analysis to better describe the fundamental physics of near zero reflection due to nanocones printed on solar cell encapsulation glass. Experimental results agreed with the theoretical analysis, and showed that these nanostructures further increased absorbed photocurrent by trapping light in the encapsulation glass. Finally, a unique device in the form of a tandem luminescent solar concentrator/silicon solar module was proposed and analyzed as a low cost and adaptable technology for increased solar power conversion efficiency. Key to this design was discovery of new, near-perfect components for light management. Exciting and innovative designs are proposed to control the light-matter interaction within these devices. Study of a photonic luminescent solar concentrator predicted that luminescence can be trapped in photonic crystal slab waveguides with near zero loss. Rigorous experimental efforts to characterize a multitude of near-perfect samples help guide these designs toward their final goals.