The light-trapping concept exploits total internal reflection to confine the incident light within the cell, thus making the effective optical path length longer than the cell physical thickness. Nanophotonic gratings pattered over the bottom or top layers of the cell and the use of suitable reflectors and AntiReflection Coating (ARC) layers may drastically increase the optical absorption length of the quantum-dot layers, thus overcoming through light management the technological limitation related to the maximum number of quantum dot layers that can be stacked within the solar cell without undermining the overall material quality.
Conceptual sketch of light trapping in a thin film solar cell realized through nanophotonic diffraction grating.