Wave-optical front structures on silicon and perovskite thin-film solar cells

Abstract Photonic structures allow reducing the thickness of photovoltaic (PV) devices while improving their photocurrent, thereby enabling high-efficient, low-cost, and mechanically flexible solar cells. Wave-optical front structures have shown to be promising for integration in various thin-film PV technologies, as those based on silicon or perovskite semiconductors, due to a combination of: (1) Broadband absorption amplification—wavelength-sized structures provide geometrical index-matching for the impinging light, strongly reducing reflection while boosting the photons' path length within the absorber via scattering. (2) Improved electrical performance—their incorporation in the transparent contact can enable higher electrode volume, thereby improving the cells' voltage and fill factor. Such a location can also prevent increasing the cells' roughness, therefore not contributing to recombination. (3) Enhanced stability—particularly in perovskite cells, the front photonic structures block most of the harmful UV radiation that degrades such devices. Colloidal lithography methods have revealed to be highly cost-effective for the nanopatterning of such structures, allowing compatibility with industrial scalability and low-cost requirements.