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.