Optically-Boosted Planar IBC Solar Cells with Electrically-Harmless Photonic Nanocoatings

Advanced light management via front-coated photonic nanostructures is a promising strategy to enhance photovoltaic (PV) efficiency through wave-optical light-trapping (LT) effects, avoiding the conventional texturing processes that induce the degradation of electrical performance due to increased carrier recombination. Titanium dioxide (TiO2) honeycomb arrays with different geometry are engineered through a highly-scalable colloidal lithography method on flat crystalline silicon (c-Si) wafers and tested on standard planar c-Si interdigitated back-contact solar cells (pIBCSCs). The photonic-structured wafers achieve an optical photocurrent of 36.6 mA cm−2, mainly due to a broad anti-reflection effect from the 693 nm thick nanostructured coatings. In contrast, the pIBCSC test devices reach 14% efficiency with 679 nm thick TiO2 nanostructures, corresponding to a ≈30% efficiency gain relative to uncoated pIBCSCs. In addition, several designed structures show unmatched angular acceptance enhancements in efficiency (up to 63% gain) and photocurrent density (up to 68% gain). The high-performing (yet electrically harmless) LT scheme, here presented, entails an up-and-coming alternative to conventional texturing for c-Si technological improvement that can be straightforwardly integrated into the established PV industry.