Monochromatic Light Trapping in Photonic Power Converters

Photonic power converters (PPC) are photovoltaic devices that convert monochromatic light into electricity. Recent records with III-V PPC have achieved 68.9% but demand high carrier lifetimes. This report shows that the introduction of light trapping can yield substantially higher efficiencies, as all the incident light is weakly absorbed and thus amenable to absorption enhancement. For PPCs with low carrier lifetimes (i.e., 1–100 ns for moderately-doped GaAs), light trapping yields significant gains by enabling thinning of the material and reduction of recombination. In this report, multiple light trapping designs are compared, including nanostructures, rear diffuse reflectors, and angular selective filters. While some light-trapping designs achieve higher ideal PPC performance, other designs are seen to be more tolerant to dimensional variation in fabricated structures and incident angles.